Home Theater Glossary

Home Cinema Guide may get a commission if you buy from a link marked with * on this page: about ads
a bookshelf speaker sitting on a shelf in a study surrounded by books

Home theater tech is filled with confusing jargon and acronyms. This glossary explains common terms in simple language to help cut through the gobbledygook. Consider it a quick reference for refreshing your memory or when you’re completely lost. I’ll update it as things change.

No need to memorize it all – just bookmark this page for whenever you need a refresher. If you’re only interested in projectors, check out the smaller projector glossary.

Quick Navigation

# | A | B | C | D | E | F

G | H | I | J | K | L | M

N | O | P | Q | R | S | T

U | V | W | X | Y | Z


100 Hz Refresh Rate
A 100 Hz refresh rate measures how many times per second a TV or monitor updates the image on the screen. 100 Hz is typical in areas that used the old PAL TV signal, which had a frame rate of 50 Hz. Doubling the original 50 Hz refresh rate to 100 Hz can make fast-moving scenes in movies and games look smoother and more fluid. However, it doesn't necessarily make things look better. Learn more: TV refresh rates explained
1080i is a high-definition video resolution with 1080 horizontal lines displayed in an interlaced format. The i stands for interlaced, meaning half the lines are displayed each refresh cycle, alternating between odd and even rows. 1080i has a resolution of 1920 x 1080 pixels with a 16:9 widescreen aspect ratio. HD broadcast TV often uses 1080i (or 720p) to overcome bandwidth restrictions. However, 1080p progressive scan video is better suited for HDTVs and projectors, displaying each frame's full image without interlacing artifacts. Learn more: 1080i vs 1080p
1080p is a display resolution of 1920 x 1080 pixels (2,073,600 pixels in total). The 'p' stands for progressive scan, meaning the image displays sequentially line-by-line rather than interlaced alternate odd and even lines. It is considered the standard resolution for HDTVs and Blu-ray to provide detailed full HD 1920 x 1080 images without interlacing or fluid motion artifacts. Learn more: Understanding TV resolutions
120 Hz Refresh Rate
A refresh rate of 120 Hz tells you how often a TV or monitor updates the picture on the screen every second. 120 Hz is typical in areas that used the old NTSC TV signal, which had a frame rate of 60 Hz. By doubling the native refresh rate from 60 Hz to 120 Hz, fast-moving scenes in movies and games appear smoother and more natural. Although, having a higher refresh rate doesn't always mean a better picture. Learn more: TV refresh rates explained
1280 x 720
1280 x 720 refers to a display or video resolution of 1280 pixels horizontally by 720 pixels vertically (921,600 pixels). It has an aspect ratio of 16:9, which matches the widescreen format used for HDTV. 1280 x 720 is the minimum resolution for high-definition video and is sometimes called '720p'. Modern HDTVs, projectors, and consumer camcorders support at least 1280 x 720 for smooth, detailed widescreen imaging. Due to the size and shape of the pixels that make up the screen, some HD-ready displays may have a slightly different native resolution, e.g., 1366 x 768 (1,049,088 pixels) or 1024 x 768 (786,4321280 pixels).
16:9 is the standard aspect ratio of HDTV. It means the shape of the picture is 16 units across and 9 units down. It is also known as 1.78:1 – which is 16 ÷ 9.
1920 x 1080
1920 x 1080 is a native or image resolution of 1920 pixels horizontally by 1080 vertically. With around 2 million total pixels (2,073,600), it is considered full high definition (Full HD or 1080p), providing clear, detailed images. The 16:9 widescreen aspect ratio of 1920 x 1080 matches the HDTV standard and Blu-ray formats. Most HDTVs, projectors, and consumer camcorders today support at least 1920 x 1080 resolutions.
192kHz/24-bit DAC
A 192kHz/24-bit DAC decodes digital audio signals at a high resolution of 192kHz and a 24-bit depth, offering superior sound clarity. It allows for a more detailed and lifelike audio reproduction, bringing you closer to studio-quality sound. For comparison, standard CD audio is 44.1kHz/16-bit.
2160p is an ultra-high-definition video resolution with 2160 horizontal lines displayed in progressive scan format. The p indicates progressive scanning, so the full frame is displayed each cycle for smooth motion. With a resolution of 3840 x 2160 pixels, 2160p quadruples the detail of 1080p full HD. 2160p resolution at 50/60fps is the standard for 4K UHD TVs and projectors to display maximum clarity without interlacing artifacts. Learn more: Understanding TV resolutions
3840 x 2160
3840 x 2160 refers to an UHD display or image resolution of 3840 pixels horizontally by 2160 pixels vertically. With over 8 million pixels total (8,294,400), 3840 x 2160 is four times the 1920 x 1080 full HD pixel count. Its 16:9 widescreen aspect ratio matches 4K standards for digital film and TV. 3840 x 2160 provides some of the sharpest, most lifelike visuals available today on high-end 4K TVs, projectors, and content sources.
3D Audio
3D audio refers to surround sound technologies that create immersive three-dimensional audio experiences in home theaters. It makes viewers feel enveloped in sound from all directions, distances, and heights - as if inside the action. A home theater system uses object-based audio formats like Dolby Atmos, DTS:X and Auro-3D, which use a special mixing technique to place audio objects around the sound field on top of the traditional 5.1 or 7.1 base. The result is a 360-degree audio environment where sounds emanate from distinct points in space, fully immersing the listener.
4:3 is the original standard aspect ratio for television programs. It means the shape of the picture is 4 units across and 3 units down. It is becoming much less common as transmissions switch to widescreen. However, many old shows originally filmed in 4:3 will still display in this aspect ratio on a widescreen TV. 4:3 is also known as 1.33:1 because 4 ÷ 3 = 1.33.
4320p is an 8K UHD video resolution with 4320 horizontal lines displayed in progressive scan format. The p indicates progressive scanning, so the full frame is displayed each cycle for smooth motion. With a resolution of 7680 x 4320 pixels, 4320p has sixteen times the detail of 1080p full HD and four times 4K UHD. Learn more: Understanding TV resolutions
4096 x 2160
4096 x 2160 is a 4K format used in professional digital movie cameras and cinema projection with over 8.8 million pixels (8,847,360). It has a 7% wider image than the 3840 x 2160 resolution used for consumer 4K UHD. The extra pixels provide more resolution for 2.39:1 cinematic widescreen formats. Some high-end 4K projectors and screens in home theaters support 4096 x 2160 for improved movie resolution. However, most consumer video releases trim the image to 3840 x 2160 to match the 16:9 aspect ratio used in consumer displays.
480i refers to a standard definition digital video resolution of 480 interlaced lines. The i indicates an interlaced format, displaying half the lines each refresh cycle. 480i has a total display resolution of 640 x 480 pixels (307,200) with a 4:3 aspect ratio matched to older televisions. Countries that traditionally use NTSC, mainly in the Americas and Japan, commonly adopt 480i because while analog NTSC transmits 525 lines at 60 hertz, only 480 are visible.
480p represents a video display resolution that features 480 vertical pixels. The 'p' represents progressive scan, meaning the system displays images in a smooth sequence instead of interlacing. Typically, 480p has a 4:3 aspect ratio with a horizontal resolution of 640 pixels or a 16:9 aspect ratio with up to 854 pixels. Early plasma TVs often used this resolution, and it is classed as Enhanced Definition.
The 4K video resolution is part of the Ultra HD family. Also known as 4K UHD, a 4K image is recorded using progressive scan and has a minimum resolution of 3840 x 2160 (8,294,400 pixels) with a 16:9 aspect ratio. 4K has four times as many pixels as 1080p Full HD. Learn more: Understanding TV resolutions
5.1 Surround Sound
5.1 surround sound is a multichannel audio setup comprising five full-range speakers and a low-frequency effects (LFE) subwoofer channel. The five speakers are front left, front right, center, surround left, and surround right. The '.1' refers to the single LFE subwoofer channel for deep bass effects. 5.1 provides an immersive 360-degree sound field by surrounding the listener with left, right, and rear directional audio and is used in home theater systems, movie soundtracks, video games, and music playback. Advanced surround sound formats like Dolby Atmos build on 5.1 by adding overhead and other channels.
50 Hz Refresh Rate
A 50 Hz refresh rate measures how many times a TV or monitor updates the picture on the screen every second. It is used in countries where the mains electricity supply runs at 50 Hz. TVs and monitors use a 50 Hz refresh rate to synchronize with the power supply and reduce flicker. Learn more: TV refresh rates explained
576i is a standard-definition digital video format primarily used in PAL and SECAM regions, which use 50 Hz electric power. The resolution features 576 interlaced lines of pixels, giving it the name 576i, where 'i' stands for interlaced. It is similar to 480i, used in countries with a 60 Hz power frequency and linked with the NTSC color system. 576i supports 4:3 and anamorphic widescreen aspect ratios.
6.1 Surround Sound
6.1 surround sound is an audio format similar to 5.1 surround sound. However, 6.1 adds a rear center speaker, providing better depth perception and spatial location of sounds behind the listener. It is an older surround sound format and isn't widely available.
60 Hz Refresh Rate
A 60 Hz refresh rate indicates the number of times a TV or monitor updates the picture on the screen every second. This rate is commonly used in places like North America, where the mains electricity supply runs at 60 Hz. The synchronization of the refresh rate with the power supply minimizes flickering on the screen and ensures a stable viewing experience. Learn more: TV refresh rates explained
7.1 Surround Sound
7.1 surround sound is an expanded multichannel audio system based on standard 5.1 surround sound. However, 7.1 adds two additional surround channels - a left surround rear and a right surround rear. The extra rear channels provide sound from directly behind the listener in addition to the side surround channels and enable more precise positioning of sounds behind the listener for an even more immersive and spatial audio experience. 7.1 surround sound is used for theatrical mixes, home theaters, and video games but is less common than 5.1 audio.
720p is a shorthand description for a type of high-definition picture. 720p is the minimum requirement for a high-definition image and is often used to describe a flat-screen TV's resolution. '720' refers to the number of vertical pixel lines that make up one frame of the picture. The 'p' means the image will be displayed using progressive scan. Learn more: 720p vs 1080p
7680 x 4320
7680 x 4320 is a display or image resolution with a width of 7680 pixels and a height of 4320 pixels (33,177,600 pixels total). Commonly known as 8K UHD (Ultra High Definition), this resolution offers four times the pixel count of 4K UHD and sixteen times that of 1080p Full HD. It provides an incredibly detailed and sharp visual experience, especially on larger screens. 8K is primarily used in high-end TVs, monitors, and professional video production, setting a new standard for image clarity.
Also known as 8K Ultra High Definition (UHD), 8K has a display resolution of 7680 x 4320 (33,177,600 pixels). It offers four times the pixels of 4K UHD and sixteen times that of 1080p Full HD. 8K delivers very detailed and crisp visuals, primarily used in top-tier televisions, monitors, and professional cinematography.
9.1 Surround Sound
9.1 surround sound is an advanced audio format used in home theaters. It builds upon the 7.1 surround sound layout by adding two overhead or height channels, enhancing the vertical spatiality of the audio experience. Initially, AV receivers used Dolby Pro Logic IIz to upscale standard surround sound audio to 9.1. More recently, object-based audio systems like Dolby Atmos used this layout. However, the convention calls it 5.1.4 or 7.1.2 if using Dolby Atmos, rather than 9.1.
Return to Top


A/B Speaker Switch
Speaker A/B switching allows users to connect two sets of speakers to one amplifier or receiver and switch between them. This amplifier feature is helpful for listening in different rooms or comparing two sets of speakers without physically disconnecting and reconnecting them. However, not all amplifiers have A/B switching, and even if they do, they may not allow simultaneous playback on both sets.
ACCUEQ is Onkyo's proprietary auto-calibration system for home theater receivers and systems. It analyzes the acoustic characteristics of the listening environment and adjusts various audio parameters, such as speaker size, level, and distance, to achieve optimal sound playback tailored to the room. ACCUEQ also considers ambient background noise to maintain a clear audio output even when external noises are present.
Acoustic Transparency
Acoustic transparency projector screens use a special material with tiny holes, allowing sound to pass through without affecting quality or volume. This screen type lets you place speakers behind the screen for a more natural, immersive audio experience. Acoustic transparency works well in home theaters where audio quality matters, but speaker placement space is limited.
Active 3D
Active 3D technology uses battery-operated shutter glasses that quickly open and close in sync with the alternating images displayed on the TV. This creates a 3D effect by delivering full 1080p resolution to each eye separately, providing a clearer, more detailed picture than passive 3D. The downside is the glasses are typically heavier, more expensive, and need to be recharged or have their batteries replaced.
Active Speaker
An active speaker has a built-in amplifier, eliminating the need for an external amp or receiver. It simplifies an audio setup as it only requires a power source and an audio signal. This design often results in a more tailored sound, as the amplifier is specifically matched to the speaker's drivers. A passive speaker is similar but without the internal amplification.
Active Subwoofer
An active subwoofer is a self-powered bass speaker often used in home theater systems. It gets a low-power line level signal from an AV receiver, boosts it with its built-in amplifier, and then plays the amplified sound. You can adjust its output using controls on the subwoofer itself. The alternative, a passive subwoofer, needs an external amplifier to function.
Adaptive Sync
Adaptive Sync is a technology that synchronizes a display's refresh rate with the frame rate of the graphics card. It eliminates screen tearing and reduces stuttering, leading to a smoother gaming experience. AMD's FreeSync and NVIDIA's G-Sync are both implementations of adaptive sync technology.
ADC (Analog-to-digital Converter)
An analog-to-digital converter (ADC) transforms analog audio and video signals into digital data for processing. It samples the analog waveform and converts it into binary code for digital devices. ADCs allow analog sources like VCRs to interface with digital home theater components. Advanced ADCs also improve analog inputs by digitizing with higher bit depths and sampling rates for enhanced clarity and resolution. Once converted, the audio can be stored, edited, or played back using digital equipment.
AI Upscaling
AI Upscaling refers to the use of artificial intelligence algorithms to enhance the resolution of images or videos. For example, transforming 1080p content to appear as 4K or 8K. AI upsampling goes beyond traditional upscaling methods by analyzing the content, detecting patterns, and filling in the missing details to create a sharper, clearer, and more detailed image.
AirPlay is Apple's proprietary wireless streaming technology. It lets you stream audio, video, and other media content from Apple devices to compatible speakers, TVs, or other AirPlay-enabled devices. A newer version, AirPlay 2, offers multi-room audio streaming.
A-La-Carte TV
A-La-Carte TV is a service model where viewers can select and pay for individual TV channels rather than forcing them to buy bundles of channels. This method allows customers to only pay for the channels they actually watch, potentially saving money compared to traditional bundled offerings.
Alexa Voice Control
Alexa Voice Control refers to voice commands processed by Amazon's virtual assistant, Alexa. This feature lets you control various smart devices, including home theater systems, using just your voice. Typical commands include adjusting volume, changing tracks, or switching inputs.
ALLM (Auto Low Latency Mode)
ALLM, or Auto Low Latency Mode, automatically adjusts a display's latency settings for optimal performance during gaming or real-time interactive content. It is part of the HDMI 2.1 specification. When you connect compatible ALLM devices, they will automatically switch to their gaming modes, enabling the best low-latency settings for gaming. All devices in the chain need to support this.
Ambient Light Rejection (ALR)
ALR projector screens reflect light toward the viewer, making the image brighter in rooms with ambient light. The specialized surface prevents washout from lights or windows. Though more expensive than standard screens, ALR improves picture quality where controlling lighting is difficult, like in living rooms.
An amplifier boosts the power of an audio signal, making it louder. You need an amplifier for the audio sent by most source devices, like Blu-ray players, CD players and cable boxes, because they output the audio at a low level, called line level. In home theater setups, an amplifier or receiver drives the speakers and ensures they produce sound at the desired volume. Some speakers, called active or powered speakers, have built-in amplifiers.
Amplifier Slew Rate
The amplifier slew rate measures how quickly the amplifier can respond to a change in input level. It is usually measured in volts per microsecond (V/μs). The main impact of an amplifier's slew rate is how accurately it can reproduce high frequencies when there is a rapid change in voltage. A well-designed amplifier will have a high slew rate, reproducing the high frequencies within our hearing range with little or no distortion. A good starting point for an audio amplifier would be a slew rate of around 10 V/μs. Better amplifiers will have higher slew rates than this.
Analog Audio Input/Output
Analog Audio Input/Output refers to connectors that transmit or receive audio signals in an analog format. Common examples include RCA or 1/4-inch jacks. Unlike digital signals, analog signals can degrade with interference or distance, potentially affecting audio quality.
Anamorphic Lens
An anamorphic lens allows home theater projectors to display widescreen movies in their original format without black bars or distortion. The lens condenses the widescreen image to fit the projector's sensor, then stretches it back to full width on the screen. This technique provides an enhanced viewing experience for ultra-wide cinemascope films. However, anamorphic lenses can add cost and may require professional installation.
Android TV
Android TV is a version of Google's Android operating system optimized for televisions. It provides a smart TV experience, allowing users to access apps, games, and streaming services directly from their TV. Google Play Store is available on Android TV, giving access to a vast library of apps.
ANSI Lumens
ANSI lumens measure projector brightness as defined by the American National Standards Institute. Higher lumens indicate a brighter projected image. This specification is essential when selecting a home theater projector, especially for rooms with ambient light or large screens. 1500-2000 lumens is usually sufficient for dark, dedicated home theaters. In rooms with some ambient light, look for 2500-4000 lumens. Bright rooms with lots of light require 4000+ lumens for a visible picture. However, brightness is just one factor to consider, along with contrast, color accuracy, resolution, and other features.
Anynet+ is Samsung's implementation of the HDMI-CEC (Consumer Electronics Control) feature, which allows users to control up to 12 compatible devices that are connected via HDMI with a single remote.
aptX is an audio codec used for wireless Bluetooth audio streaming. Developed by Qualcomm, aptX provides better sound quality than the standard Bluetooth SBC codec. It allows for near CD-quality sound over Bluetooth, reducing the bit rate without affecting audio quality too much or introducing latency issues. The maximum bitrate for aptX is 325 kbps at 44.1 kHz and 384 kbps at 48 kHz.
aptX HD
aptX HD is a wireless audio coding technology developed by Qualcomm for high-definition Bluetooth transmission. It can wirelessly stream 48kHz/24-bit audio at bitrates up to 576 kbps, close to CD quality of 1411 kbps. aptX HD enables wireless speakers and headphones to receive uncompressed, near-lossless audio from compatible TVs, phones, and media devices. Using aptX HD ensures home theater wireless audio retains detailed sound quality without the compression artifacts and noise found in standard Bluetooth.
Aspect Ratio
The aspect ratio defines the shape of a video image - or a TV or projector screen. The aspect ratio of an image is its width divided by its height. For example, the traditional shape of a television picture is 4:3. This means four units across and three units down. Four divided by three = 1.33. So, the aspect ratio of a 4:3 image is 1.33:1 - or 1.33 times wider than long. Looking at the back of a DVD case will tell you the film's aspect ratio. It may say 4:3, or it may say 1.33:1 - or both! The aspect ratio of modern TVs and high-definition pictures is 16:9 - or 1.78:1. Learn more: Movie Aspect Ratios
Asynchronous USB
Asynchronous USB refers to a digital audio connection where the external device, often a DAC, controls data flow rather than the computer. An asynchronous connection reduces timing errors or jitter, producing better sound quality than synchronous USB connections.
Audio Channel
An audio channel represents a distinct stream of audio. Mono audio is a single audio channel, while stereo audio is 2-channel. In home theater systems, multichannel audio formats like 5.1 or 7.1 have several channels dedicated to a specific speaker, such as front left, center, or rear right. This arrangement helps create a surround sound experience.
Audyssey is a sophisticated room correction technology used in many Denon and Marantz AV receivers to optimize audio performance based on a room's specific acoustic properties. It takes measurements from multiple listening positions, creating an optimized sound profile tailored to the room. Different versions, like the basic MultEQ, the more detailed MultEQ XT, and the top-tier MultEQ XT32, offer varying levels of precision - and the new MultEQ-X version allows external computer-based calibration. Additional features include Dynamic EQ, which maintains sound balance at varying volume levels, and Dynamic Volume, which stabilizes volume fluctuations such as those experienced during commercial breaks.
Auro-3D is an immersive audio format that adds a height layer to traditional surround sound. Using additional speakers above the listening area creates a more three-dimensional soundstage, offering an enhanced sense of immersion compared to conventional systems. Auro-3D support is mainly found on high-end AV receivers and is a less common alternative to Dolby Atmos and DTS:X.
Auto Calibration
Auto Calibration is a feature found in many modern AV receivers. It automatically adjusts various audio parameters, such as speaker levels, distances, and equalization, based on measurements taken with a microphone. This calibration ensures optimal sound performance tailored to the room's characteristics. Common auto calibration systems are Audyssey MultEQ (Denon and Marantz), YPAO (Yamaha), MCACC (Pioneer), AccuEQ (Onkyo), ARC (Anthem) and Dirac Live (Arcam, NAD, Denon, Pioneer, Onkyo).
Auto Standby
Auto Standby is an energy-saving feature where a device, like an amplifier or receiver, automatically goes into a low-power standby mode if it doesn't detect an audio signal for a set period. It helps reduce power consumption when the system is not in use.
AV Amplifier
An AV amplifier is the same as an AV receiver, except it has no built-in radio tuner.
AV Receiver
An AV receiver is the central hub of a home cinema system, acting as both an amplifier and processor for surround sound audio and a switcher for multiple input devices. It quickly switches between input sources and handles the video and audio signals. The receiver sends video to the connected display device and audio to the speakers. Learn more: How to choose the best AV receivers
Return to Top


Backlit LED TV
A backlit LED TV has blocks of LED lights installed behind the screen. Advanced models can independently switch the blocks on or off, which is called local dimming. This results in an improved contrast ratio compared to edge-lit LED TVs and standard LCD TVs. Learn more: Backlit vs edge-lit LED TVs
Balanced Cable
A balanced cable has three conductors: positive (or 'hot'), negative (or 'cold'), and ground. These connections, found in XLR and TRS jacks, carry identical audio signals but in opposite phases. This design counters noise interference, especially over long cables, making them a preferred choice in professional audio setups.
In audio, bandwidth describes the range of frequencies a system or component can reproduce, marking the difference between the highest and lowest frequencies produced with fidelity. In digital transmission contexts, bandwidth pertains to the data rate.
Bass Management
Bass management is a feature in most AV receivers that directs low-frequency effects (LFE) channel audio and frequencies below the 'crossover point' to the subwoofer. The receiver sets the crossover point during automatic calibration based on each speaker's bass capabilities. Bass management creates a cleaner sound and reduces strain on the AV receiver.
Bass Port
A bass port, also called a bass reflex port, is a hole or tube incorporated into a speaker cabinet for improved low-frequency sound reproduction. Its primary function is to allow air to move in and out, balancing the air pressure inside the cabinet. As the speaker's active driver (or woofer) moves, it generates changes in internal air pressure. The bass port releases this pressure, helping to enhance and extend the speaker's low-frequency response. This ported speaker design can produce deeper bass than a sealed speaker of similar size. However, a poorly designed bass port might introduce unwanted noise or "chuffing" at higher volumes or with fast bass notes. Large ported speakers and subwoofers can offer extended bass, but which may be hard to control in smaller rooms.
Bi-amping involves using two separate amplifiers (or separate channels of a multichannel amplifier) to power a speaker's high-frequency and low-frequency drivers separately. Wiring the speakers this way can offer better control and improved sound quality. Bi-amping is more common with stereo speaker systems for getting the best performance for music. However, many AV receivers provide the option of bi-amping the front left and right speakers, although this will reduce the number of channels available for surround sound. Bi-amping is different from bi-wiring, which uses a single amplification channel with two sets of cables.
Bipole Speaker
A bipole speaker has two sets of speaker drivers and sends the sound from two sides of the speaker cabinet at the same time. It is ideal as a surround speaker in a 5.1/7.1 system, spreading the audio better than standard direct-radiating speakers and creating a less directional sound. A similar alternative is a dipole speaker.
Bitrate denotes the amount of data processed per unit of time in digital audio and video files. A higher bitrate generally produces better quality, as it represents more detail. Audio is usually measured in kilobits per second (kbps). For example, standard MP3 files often have bitrates of 128, 192, or 256 kbps, while stereo CDs have a bitrate of 1,411 kbps. High-definition multichannel audio, like on a Blu-ray, can exceed 5,000 kbps. For video, higher bitrates, often measured in megabits per second (Mbps), provide clearer and crisper visuals, especially in scenes with a lot of movement or intricate details and often exceed 20 Mbps (20,000 kbps).
Bitstream Output
Bitstream output sends a raw digital audio signal from a source device to an external decoder, such as an AV receiver. The receiver then decodes formats like Dolby Digital or DTS to produce multichannel sound. For instance, when using a Blu-ray player, instead of letting it decode the audio, you may send the bitstream output directly to your home theater system. The AV receiver then handles the decoding, often producing a more accurate or higher-quality sound experience.
Bi-wiring uses two sets of speaker cables from a single amplifier output to connect to separate input terminals on a speaker. One pair carries the signal for the tweeter (high frequencies) and the other for the woofer (low frequencies). Bi-wiring aims to reduce any potential interaction between the high and low frequencies, which might otherwise compromise sound quality. Bi-wiring differs from bi-amping, which uses two separate amplification channels for a speaker's tweeter and woofer.
Black Level
Black level refers to the depth and quality of dark or black areas displayed by a projector or screen. In simpler terms, it indicates how 'true' or 'deep' the blacks appear. A projector with good black levels will show a clear distinction between dark and slightly darker colors, enhancing the overall contrast and depth of the image. Ideally, you'd want deeper black levels for a richer, more lifelike viewing experience.
Bluetooth is a wireless technology operating on the 2.4 GHz radio band, designed for short-range data exchange between devices. In audio, it allows for streaming music from devices like smartphones directly to playback equipment, be it headphones or speakers. Home theaters use Bluetooth to connect smartphones or tablets to soundbars, AV receivers, or televisions, seamlessly playing content without cables. Some receivers can even send audio to Bluetooth headphones. Common Bluetooth audio formats include SBC, AAC, aptX, aptX HD, aptX Low Latency, and LDAC, each varying in quality and latency to cater to different listening needs.
Blu-ray Disc (BD)
A Blu-ray disc (BD) is an optical disc format for high-definition video and high storage capacity data. Blu-ray uses blue-violet lasers and smaller spot sizes than DVD, allowing for greater data density. A single-layer Blu-ray Disc can store up to 25 GB, with dual-layer discs storing up to 50 GB. The large storage capacity makes Blu-ray discs ideal for movies in 1080p high-definition and 4K Ultra HD. Blu-ray also supports advanced features like HD audio formats, HDR, wider color gamuts, and 3D content. Learn more: Blu-ray players buying guide
BT.2020 is the 10-bit color standard defined in the Ultra HD specification. It includes standards for the image resolution, frame rate, bit depth, chroma subsampling, and the color gamut. An AV receiver must support BT.2020 to pass this type of content to your 4K-compatible TV.
Return to Top


CCFL (Cold Cathode Fluorescent Lamp)
CCFL is the traditional type of lamp used as the backlight in an LCD TV. In newer TVs with LCD panels, LED lights replace CCFL backlights. Because they use LED lighting, more recent models are usually called LED TVs rather than LCDs.
CEC (Consumer Electronics Control)
CEC is a feature of HDMI that enables connected devices to communicate and share functionality. It allows unified control of multiple entertainment devices through a single remote. For example, CEC can automatically turn on your soundbar or media player when you turn on your TV. Other capabilities include controlling playback between devices, adjusting volumes and switching inputs. In different brands, CEC goes by different names, like Anynet+ (Samsung), SimpLink (LG), and BRAVIA Sync (Sony). Learn more: What is HDMI-CEC?
Chipset (Projector)
A projector's chipset is a semiconductor chip containing micromirror arrays or liquid crystals that reflect and process light. Popular chipsets are Optoma's DLP chips using mirrors, JVC's D-iLA chips built on LCoS technology, and LCD chips from Epson. When comparing projectors, the specific chipset is one of the most critical factors in determining native resolution, clarity, contrast, and overall video quality, and each type has particular pros and cons.
Chroma Subsampling
Chroma subsampling is a method video encoders use to reduce the bandwidth required to transmit video. The encoder samples the chroma (color) information in a video signal fewer times before your TV screen recreates the entire image when displayed. This method results in a smaller amount of data to transfer but with no loss in image quality. In 4:2:0, encoders sample one color every time, another half the time, and the final color not at all. Blu-ray discs store video using this method. Your TV uses an algorithm to rebuild the lossless image from the 4:2:0 data, meaning less information for your HDMI cable to carry. In 4:2:2, encoders sample one color every time and the other two colors every other time. In 4:4:4, encoders always sample each red, green, and blue color, resulting in more data to send.
Chromecast is a streaming technology developed by Google. It lets users "cast" multimedia content from smartphones or computers to a compatible TV or speaker. This capability has made it a popular choice in home theaters, allowing enthusiasts to stream their favorite movies or music from mobile apps to their larger TV screens and surround sound systems.
Class A Amplifier
Class A amplifiers have their output devices conducting continuously for the entire audio cycle. While they often produce high-quality sound with low distortion, they are less efficient and can generate more heat.
Class AB Amplifier
A Class AB amplifier combines the best attributes of both Class A and Class B amplifier designs. It operates as a Class A amplifier for low-level signals, ensuring high fidelity and switches to Class B operation for larger signal levels, optimizing efficiency. This hybrid design improves efficiency over Class A amplifiers while minimizing the crossover distortion commonly found in Class B amplifiers. Class AB amplifiers are widely used in home audio and many other applications because they balance performance with efficiency, making them suitable for various listening needs.
Class B Amplifier
In Class B amplifiers, the output devices conduct only half of the audio cycle, with one device handling the positive half and the other the negative. They're more efficient than Class A amplifiers but can introduce crossover distortion.
Class D Amplifier
Class D amplifiers, also known as switching amplifiers, rapidly switch the output devices on and off. They are known for their high efficiency and reduced heat production. This design makes them particularly favored in modern audio equipment where size and power efficiency are paramount. Pioneer uses Class D amplifiers in home theater for their Direct Energy HD amplification technology. Due to its power efficiency and compact design, many subwoofer amplifiers also leverage Class D technology.
Clipping occurs when an audio signal's amplitude exceeds a device's maximum limit, causing the waveform's peaks to be 'clipped' off, leading to distortion. This distortion is unpleasant to the ear but can also harm speakers due to the production of sustained high-energy frequencies. In a home theater or audio setup, it's crucial to ensure that amplifiers and speakers are well-matched in power and capability to prevent clipping. Overdriving an amplifier beyond its rated capacity is a common cause, making it essential to adjust volume levels carefully and use the equipment within its specified limits.
Coaxial Cable (AKA Coax)
A coaxial cable transmits various radio, video, and audio signals. It has a solid conductor core, a plastic insulation layer, a thin conductive layer, and an outer insulation layer. People use coaxial cables to carry high-frequency electrical signals over relatively long distances with minimal interference and attenuation. The shielding helps block electromagnetic interference from outside sources. Typical coaxial cable applications include cable television signals, computer networking, audio signals, and other uses requiring high-frequency transmission. Coaxial cables used for digital audio should have a 75-ohm impedance to ensure the correct signal transmission and have one RCA connector at each end. Learn more: Coaxial digital audio connections explained
Codec is short for coder-decoder. A codec encodes and decodes digital multimedia content. Home theater devices use codecs to compress and decompress video and audio into deliverable formats. Advanced codecs like H.265 enable 4K video at lower bitrates. Popular surround sound codecs include Dolby Digital, DTS, and Dolby Atmos, allowing home theaters to play high-resolution audio from compressed content.
Color Depth (AKA Bit Depth)
The color depth for video is the total number of bits used to define each color for every pixel. Most TVs use the RGB color model to display an image, creating the color of each pixel from varying amounts of red, green, and blue. 8-bit color allows for around 16 million colors. 10-bit color provides about 1 billion colors. 12-bit color allows for approximately 68 billion colors. Consumer video typically uses 8 bits for each color, like standard Blu-rays. 4K UHD Blu-ray uses 10-bit color, where the extra colors improve HDR content. The Ultra HD specification also allows for 12-bit color, but most TV screens are currently 8 or 10-bit. People often confuse color depth and chroma subsampling, but they are different things.
Color Gamut
Color gamut refers to the range of colors a projector or TV can display. It is usually measured using the CIE 1931 color space, a mathematical model describing how humans perceive color. A device with a limited color gamut may not reproduce the full range of colors in a movie or video game, resulting in less vibrant and less realistic images. As part of the 4K UHD specification, BT.2020 introduced a wide color gamut, meaning 4K projectors and screens could display many more colors than older 1080p models.
Color Temperature
Color temperature is a standard of how "warm" or "cool" the colors in a projected image appear, measured in degrees Kelvin (K). The color temperature setting of a projector adjusts the balance between blue and yellow tones in the picture. A lower color temperature produces a warmer, yellowish image, while a higher temperature produces a cooler, bluish appearance. The color temperature setting is crucial because it can affect the perceived color accuracy of the picture. Many projectors adjust the color temperature to ensure accurate and consistent colors across different lighting conditions.
Component Video
Component video is an analog video signal split into two or more separate signals, which creates a better image than composite and S-Video technology. RGB and YPbPr component video split the signal into three parts, and each uses the same type of cable to connect devices with male red, green and blue RCA connectors. Component video is a common output option on older DVD players, Blu-ray players and other audio-visual equipment, identified by the red, green, and blue female RCA connections. Learn more: Component video cable and connection explained
Composite Video
Composite video is an analog format often found in older audio-visual devices like DVD players, game consoles, and cable boxes. It is standard definition and more susceptible to interference. Composite video combines color, brightness and sync signals into a single output signal sent via a single RCA connector. Televisions separate the luma (brightness) and chroma (color) components to reconstruct the video image. However, because composite combines all the information into a shared bandwidth, it limits resolution and signal quality. While legacy home theater devices may still accommodate composite video, high-definition sources use component video or digital connections like HDMI for the best-quality video. Learn more: Composite video cable and connections explained
Contrast Ratio
The contrast ratio represents the difference between a screen's darkest and brightest colors. Specifically, it is the ratio of the luminance of the brightest color (white) to that of the darkest color (black). A higher contrast ratio typically indicates a TV's ability to display a wider range of brightness levels, leading to a more detailed and vibrant picture. We usually express contrast as a ratio, such as 2000:1, where the first number is the white's brightness and the second is the black's brightness. OLED TVs have an infinite contrast ratio because they can achieve absolute black levels, measured at zero luminance. However, real-world conditions can reduce a display's contrast. Ambient light washes out the image on TVs in bright rooms, preventing them from achieving their full measured contrast ratio. So, the contrast ratio matters most for movie viewing in darkened rooms. Therefore, don't rely on the numbers alone, as they may not reflect the contrast perceived in practice.
A crossover is an electronic component used to filter audio frequencies. Depending on the application and design, the crossover may be analog or performed by digital signal processing. A loudspeaker with multiple drivers will use a crossover to split the full-range audio signal into separate bands - usually two or three-way - but maybe more for a larger speaker. The high frequencies pass to the tweeter, and the lower frequencies go to the mid-range or woofer drivers. An AV receiver uses a crossover for bass management and directing low-frequency audio to the subwoofer.
Crossover Frequency
The crossover frequency is a setting that determines which frequencies go to each speaker. On an AV receiver, you can select the crossover frequency for each speaker in your system, below which the lower frequencies go to the subwoofer. For example, setting the crossover frequency for a center speaker to around 80Hz is common. However, the ideal setting depends on how well your speaker can reproduce low-frequency audio. If your center speaker doesn't deliver low-frequency audio well, it's best to raise the crossover to 100 or 120 Hz and send more low bass to the subwoofer. By dividing the audio frequencies correctly, the crossover frequency ensures each speaker produces the best sound, resulting in a clear and balanced audio experience.
CRT stands for cathode ray tube - the technology old CRT TVs used to produce pictures on the screen. CRT TVs had significant problems because the tubes made these old TV models large, deep, and heavy, making them difficult to maneuver. New flat-screen technologies like LED and OLED have replaced CRT displays because they are much thinner and lighter than old cathode ray tube sets.
Cylinder Subwoofer
A cylinder subwoofer uses a vertical cylindrical enclosure rather than the traditional square cabinet. The circular design minimizes internal standing waves that can cause undesirable bass peaks and dips. Cylinder subs often use downward-firing woofers and passive radiators for 360-degree bass projection. The other primary benefit of a cylinder design is it can take up less floor space than a square design. You can get huge cylinder subs that don't stick out into the room very much because they extend vertically. Audiophiles like cylinder subwoofers for tight, accurate, omnidirectional bass, perfect for listening to two-channel music or movie soundtracks.
Return to Top


DAB (Digital Audio Broadcasting)
DAB is the standard in Europe and other parts of the world for transmitting digital radio. It transmits radio digitally over the air via a network of terrestrial transmitters. DAB provides better sound quality than analog FM radio and also enables extra features like station name display and song metadata. Many home theater receivers now include built-in DAB+ tuners to access digital radio stations. In the United States, HD Radio is the primary digital radio standard rather than DAB. It is compatible with existing AM/FM radio bands.
DAC (Digital-to-analog Converter)
A digital-to-analog converter (DAC) is a device that converts digital audio into analog audio. Every audio device that handles digital audio needs a DAC in the signal path to convert it to audio you can hear. Converting digital audio to analog is necessary because most audio devices, such as speakers and headphones, only play analog signals. Many devices, such as smartphones and computers, have built-in DACs for their audio outputs, like soundcards and headphone connectors. Modern AV receivers feature premium 32-bit DACs for excellent high-resolution home theater sound. However, external DACs, such as the Chord Qutest, AudioQuest Dragonfly and the iFi Zen, can improve audio quality even more. These high-end DACs connect between your device's audio output and your headphones or speakers.
Decibel (dB)
The decibel (dB) is a unit of measurement used to express the intensity or level of sound on a logarithmic scale. This logarithmic representation makes the decibel scale especially useful for managing the wide range of amplitude levels. The quietest sound humans can hear is typically measured at 0 dB, while loud concerts can measure over 120 dB. A 3 dB increase represents a doubling of the sound's intensity. In contrast, the human ear perceives a 10 dB increase as approximately doubling the loudness. In a home theater setting, understanding dB levels can help you calibrate your audio system, from balancing the loudness of different speakers to optimizing the overall listening experience.
Deinterlacing converts interlaced video into a non-interlaced progressive scan format, which modern displays require. It combines and processes the alternating odd and even interlaced video fields to build full progressive frames. Home theater displays and media players actively perform deinterlacing so interlaced sources like DVDs, over-the-air broadcasts, and 480i/1080i transmissions can be viewed progressively. Poor deinterlacing creates jagged edges, artifacts, and flickering. In contrast, the high-quality video processing chips in high-end TVs and video devices deinterlace smoothly by interpolation and motion compensation.
Dipole Speaker
A dipole speaker has a pair of speaker drivers in the same cabinet, meaning it can send the sound in two directions. The sound in a dipole speaker is out of phase. So when one side is pushing, the other is pulling, creating a very diffuse sound that is difficult to pinpoint. Therefore, a dipole speaker is ideal as a surround speaker in a 5.1 or 7.1 system. However, installing this type of speaker in the correct position is vital to get the right effect. A bipole speaker is a good alternative as it offers more flexibility in terms of positioning.
Dirac Live
Dirac Live is an advanced room correction technology that optimizes the sound of your home theater or hi-fi system based on your room's acoustics. It measures the sound from various positions and then corrects for frequency response and other audio parameters. Dirac Live is a high-end auto room calibration solution on more expensive AV receivers like Arcam and NAD and, more recently, on some Denon and Marantz models.
Display Lag
Display lag is the delay between receiving and displaying a source signal on a screen, such as a TV, monitor, or projector. This lag can arise from various factors, including image processing, refresh rates, signal conversion, and connection methods. A low display lag of less than 30 ms ensures swift visuals and is vital for gaming activities. High display lag can disrupt experiences, causing mismatches between sound and visuals or affecting real-time interactions. Using settings like "Game Mode" can reduce such delays for optimal performance.
DLNA (Digital Living Network Alliance)
The Digital Living Network Alliance (DLNA) is a trade organization of over 250 companies that develops standards that enable digital devices to share content over a home network. A 'DLNA-certified' device can share data with other DLNA devices on the same network. A standard setup has a DLNA server that stores the digital media, like a PC or NAS drive. Then, DLNA clients can 'see' the server on the network and play the files. A client might be a TV, laptop or AV receiver. Many brands use a version of DLNA for sharing content around a home network – but they often use a different name in their menus and manuals - so you may not see it called DLNA when setting up your device. Some examples are AllShare/Screen Mirroring (Samsung), SmartShare (LG), Bravia Sync (Sony) and VIERA Link (Panasonic).
DLP (Digital Light Processing)
Digital Light Processing (DLP) is a video technology developed by Texas Instruments and used in various display systems. It is widely used in manufacturing home theater and professional projectors and sometimes in rear-projection TVs. DLP creates an image by projecting light onto a matrix of tiny mirrors. The benefits include a sharp resolution, fast response times for smooth video, excellent color accuracy, and high brightness for home theater environments.
Dolby Atmos
Dolby Atmos is an object-based surround sound format that creates a 3D audio field using height and surround sound speakers. Rather than using traditional 5.1 or 7.1 surround sound channels, a Dolby Atmos mix uses up to 128 audio objects. A 10-channel 7.1.2 bed creates a mix that will play on any standard 5.1 or 7.1 system. Then, systems that support Dolby Atmos can place a further 118 objects around the sound field. Learn more: Understanding surround sound formats
Dolby Atmos Height Virtualization Technology
Dolby Atmos height virtualization uses advanced signal processing to create an immersive audio experience without overhead or up-firing speakers. Sophisticated filtering and phase shifts simulate overhead audio cues using traditional listener-level speakers. The result is a sense of 3D spatiality and envelopment, with sounds appearing to originate from above the listener. You can find Dolby Atmos Height Virtualization Technology on many modern AV receivers, including budget models. Check the features for a receiver before buying if you want this. An alternative is DTS Virtual:X, which performs a similar task.
Dolby Digital Plus (Enhanced AC-3)
Dolby Digital Plus (AKA E-AC-3) is an advanced digital audio codec from Dolby Laboratories designed for high-definition streaming, broadcast, and audio-visual media. DD+ supports more audio channels than Dolby Digital, offers better sound quality, and is popular for streaming services due to its support for a wide range of bitrates and Dolby Atmos metadata.
Dolby Pro Logic II
Dolby Pro Logic II is an audio signal processing technology developed by Dolby that replaces the original Pro Logic system. It upscales stereo audio to 5.1 channels, making it suitable for playback on multichannel speaker setups and providing a more immersive listening experience. You can find it on many devices, such as AV receivers and game consoles, although newer devices now use Dolby Surround.
Dolby Pro Logic IIx
Dolby Pro Logic IIx is similar to Dolby Pro Logic II, except it creates a 6.1 or 7.1 surround sound mix from either stereo or 5.1 soundtracks.
Dolby Pro Logic IIz
Dolby Pro Logic IIz is an improvement on Dolby Pro Logic IIx that adds a new height dimension to surround sound. For Dolby Pro Logic IIz, you need two speakers above the usual front left and right speakers to create a more realistic feel to certain sound effects - especially wind and rain. You can add these height speakers to a 5.1 system to create 7.1 (with front height speakers instead of back left and right) or a 7.1 system to create a 9.1 system. The AV receiver must be compatible with these specific speaker configurations for this option to be available.
Dolby Surround
Dolby Surround, released in 2014, is an upmixing algorithm featured in many AV receivers. It takes stereo or surround soundtracks and adapts them to fit your room's speaker layout. For instance, it can upmix a stereo soundtrack to use a complete 5.1 surround sound system or expand a 5.1 soundtrack to incorporate Dolby Atmos height speakers. This technology is an updated version of the older Dolby Pro Logic series. Licensing limitations might restrict its use solely to Dolby audio tracks. Confusingly, there was an earlier surround sound format from 1982, also named Dolby Surround; the 2014 release is a distinct, more advanced upmixing version. Learn more: Understanding AV receiver listening modes
Dolby TrueHD
Dolby TrueHD is a multichannel audio format developed by Dolby and used on Blu-ray discs. Dolby TrueHD uses lossless compression, meaning it compresses the data to fit on the disc. But, you hear the audio exactly as it was on the studio master tapes, with a wide dynamic range, deep bass, and a sparkling top end. To fully enjoy the experience, a quality sound system is necessary. It competes with DTS-HD Master Audio on a Blu-ray disc, and you usually get one or the other.
Dolby Vision
Dolby Vision is an HDR (High Dynamic Range) format that optimizes picture quality on a scene-by-scene basis. It uses dynamic metadata to fine-tune each frame's brightness, contrast, and color. Supporting televisions can analyze Dolby Vision metadata in real-time and adjust settings accordingly, providing an enhanced viewing experience from Dolby Vision content found on 4K Blu-ray Discs and streaming services.
Dolby Vision IQ
Dolby Vision IQ is a technology that improves the performance of Dolby Vision in different ambient lighting conditions. The TV detects how dark or bright the room is and uses the Dolby Vision metadata to alter the picture accordingly, enabling the clearest image in various environments. The TV will need a built-in light sensor for this to work. The first brands to support this technology are LG and Panasonic.
DSD (Direct Stream Digital)
Direct Stream Digital (DSD) offers an alternative to the more common PCM (Pulse Code Modulation) used in most digital audio systems. Instead of quantizing audio into 16 or 24 bits at 44.1kHz or 96kHz, DSD employs a 1-bit system at a much higher sampling rate, often 2.8MHz. This high rate captures the nuances and subtleties of audio with an approach mimicking analog waveforms. Many audiophiles and enthusiasts argue that DSD provides a warmer and more natural sound than PCM formats. Not all devices support this high-definition format because DSD playback often requires specialized equipment or software.
DSEE HX (Digital Sound Enhancement Engine HX)
Developed by Sony, DSEE HX is a technology that upscales compressed digital music files, restoring high-range sound and producing clearer, richer audio.
DSP (Digital Signal Processing)
Digital Signal Processing (DSP) is a complex computational process applied to audio signals to achieve specific sound qualities or effects. At its core, DSP manipulates audio waveforms to improve or adapt sound to certain conditions. Home theater systems use DSP for a variety of tasks. For example, it can create virtual surround sound in setups with fewer speakers or recreate the acoustics of famous concert halls. Also, auto-calibration algorithms use DSP for correcting room acoustics problems. Advanced AV receivers often have multiple DSP modes, allowing users to select the best sound mode for their content, whether a movie, music or a game.
DTS Neo:6
DTS Neo:6 is an audio signal processing technology developed by Digital Theater System (DTS). It creates a 5.1 or 6.1 surround sound mix from a standard 2-channel stereo soundtrack. DTS Neo:6 is found on many devices, such as AV receivers and game consoles and gives a better experience for those people with a surround sound system. On newer devices, it has been replaced by DTS Neural:X.
DTS Neural:X
DTS Neural:X is an audio upmixing technology developed by Digital Theater System (DTS). It takes stereo or basic surround sound and expands it to use all available speaker channels. Home theater receivers and processors with Neural:X can transform 2-channel stereo into 11-channel immersive audio, creating a wider, more enveloping soundstage matching the speaker layout. DTS Neural:X is a competitor to Dolby Surround, although often found together on modern AV receivers. Due to licensing restrictions, you may only be able to use it on DTS audio soundtracks. Learn more: Understanding AV receiver listening modes
DTS Virtual:X
DTS Virtual:X is a surround sound technology that uses psychoacoustic processing to create immersive 3D audio from traditional speaker layouts. Advanced algorithms analyze source audio to place sounds virtually anywhere in a 3D audio space for an enveloping experience. Virtual:X adds height and spatial dimensions to surround sound without requiring height or other specialty speakers. Many modern AV receivers provide DTS Virtual:X as a listening mode. However, it's only on some models, so check if you want this before buying. An alternative solution that does a similar job is Dolby Atmos Height Virtualization Technology.
DTS:X is an object-based surround sound audio format developed by DTS. Like Dolby Atmos, a DTS:X soundtrack can create a 3D sound field using a combination of standard surround sound speakers and height speakers. However, a DTS:X soundtrack adjusts to the speaker layout in your room. So you can experience DTS:X audio from a range of speaker layouts, not just those with height speakers. Your AV receiver must support DTS:X to use it, and you will only find it on certain Blu-ray discs. Learn more: Understanding surround sound formats
DTS-HD Master Audio
DTS-HD Master Audio is a lossless audio codec that compresses and encodes multichannel surround sound without quality loss. Blu-ray discs and other home theater sources use DTS-HD MA to deliver crystal clear 7.1 channel audio, including 192kHz/24-bit formats. You will need an AV receiver that can decode this audio type to hear it, and it is an alternative to Dolby TrueHD. Learn more: Understanding surround sound formats
DVD-Audio is a digital audio format designed for DVD. DVDs can store and play higher-quality audio than CDs because they have more disc space. DVD-Audio allows high-resolution stereo audio tracks up to 192 kHz/24-bit and 5.1 surround sound up to 96kHz/24-bit resolution.
DVI (Digital Visual Interface)
DVI is a video connection interface developed to transmit uncompressed digital video from source devices to displays. However, while the DVI-D version sends digital video, DVI-I and DVI-A support analog video for compatibility with older VGA connections. Home theater components like Blu-ray players and computers can use DVI to send high-quality 1080p/60Hz video to monitors, TVs, and projectors in home theater setups. While HDMI has overtaken DVI, the interface still carries pristine, all-digital video signals between home theater sources and displays for accurate video reproduction. Learn more: DVI connector and cable explained
Dynamic HDR
Dynamic HDR is a version of HDR that can change the metadata frame-by-frame. Standard HDR sets a fixed brightness and color range for a complete movie or TV show. Dynamic HDR can specify a different brightness and color gamut for each scene. Technologies that use Dynamic HDR are Dolby Vision and HDR10+.
Dynamic Iris
A dynamic iris is a feature in some projectors that improves the image's contrast and black level. It works by adjusting the amount of light passing through the lens based on the projected image's brightness. This feature helps create more realistic and immersive movie experiences. However, not all projectors have a dynamic iris, and its usefulness depends on your room's lighting conditions and screen size.
Dynamic Power
Dynamic power, also known as peak power, refers to an amplifier's capability to deliver bursts of high power output for short durations, usually to handle complex musical passages or intense sound effects in movies. Unlike continuous RMS power ratings, which measure an amplifier's long-term performance, dynamic power focuses on these transient peaks. While average RMS power is more helpful in understanding day-to-day use, dynamic power tells you how an amplifier will cope with sudden bursts of energy. Manufacturers of sound systems like to quote dynamic power figures because they sound more impressive than average RMS figures.
Dynamic Range
Dynamic Range is the difference between an audio signal's quietest and loudest sound. A typical movie soundtrack usually has a wide dynamic range, often changing from soft dialogues to booming action scenes. Reproducing this dynamic range effectively in a home theater relies on the amplifier, which must reproduce sound without noise or distortion, and the speakers, which should effectively produce both soft and loud sounds. For the best results, having both components work together perfectly is crucial.
Dynamic Volume
Dynamic Volume is a technology designed to analyze and adjust audio levels in real time, ensuring a uniform listening experience. It is found in AV receivers that use the Audyssey room correction software, like those from Denon and Marantz. Leveling the sound is handy for content with varying volume levels, such as transitioning from a quiet scene in a movie to a loud commercial. Or for playing a movie late at night. Other brands have software to balance the output volume, including Dolby Laboratories (Dolby Volume), DTS (DTS TruVolume), Yamaha (Adaptive DRC), and SRS Labs (SRS TruVolume). Each brand's approach might differ, but the core objective remains - consistent volume output across varied content.
Return to Top


Eco Mode
Eco Mode is a feature on many electronic devices designed to reduce energy consumption. By activating Eco Mode, your device operates with optimized efficiency, often by scaling down performance or turning off certain features when not needed. This not only conserves energy but can also extend the device's lifespan. Many AV receivers have an eco mode to save power. But be aware this will also affect the overall sound quality and performance.
Edge-lit LED TV
Edge-lit LED TVs have their LED backlights arranged around the screen's perimeter, resulting in a thin profile and reduced power usage. The LEDs shine inward to illuminate the screen, meaning fewer LED zones than backlit TVs. While this reduces cost, it also lowers image quality, causing uneven brightness and illumination issues. Learn more: Backlit vs edge-lit LED TVs
EDTV (Enhanced Definition Television)
EDTV is an enhanced version of standard-definition TV pictures. In short, it is better than SDTV but less good than HDTV. EDTV has the same number of lines of vertical information per frame as SDTV - the difference is it uses progressive scan rather than interlaced scan. So, an EDTV signal is 480p or 576p (depending on where you live). Even though there is the same amount of video information as an SDTV signal, the progressive scan will produce a sharper image as it reduces the artifacts produced by interlacing.
An equalizer is a device or software feature that adjusts the balance between different frequencies in audio. By tweaking an equalizer, you can tailor sound profiles to your preferences or to compensate for room acoustics. Equalization is especially useful when specific frequencies sound too dominant or are barely audible. Graphic and parametric equalizers are the two main types found on audio equipment.
Ethernet connects devices in a local area network (LAN) to communicate and share data. It typically uses physical cables, providing stable and fast data transfer rates. In home theaters, Ethernet connections ensure smooth streaming of high-quality audio and video content. Wi-Fi is a wireless alternative, though Ethernet generally offers more consistent speeds.
Return to Top


Fan Noise
Fan noise refers to the sound that comes from the cooling fan in a projector. Some projectors have quieter fans or offer a "quiet mode" to reduce fan noise, while others may have louder fans that you cannot adjust. Fan noise can be distracting during quiet moments of a movie or video game, so it's essential to consider the noise level of a projector's fan when buying a projector.
Flat Screen TV
Flat screen TVs use slim display technologies like LCD, LED, OLED, and plasma to create thin television panels. These televisions integrate the display and electronics into a single compact unit, contrasting with the older bulky CRT tube TVs. Other advantages of flat screen TVs are they mount flush on walls, require less space and blend seamlessly into living room décor.
Foot-lamberts are a unit of measurement for the brightness of a projected image on a screen. It tells you how much light is reflected from a 1-foot by 1-foot area of the screen and is helpful as a guide to the required amount of light in different viewing conditions.
Frame (and Frame Rate)
A video frame contains a still image of footage captured at a specific moment. The frame rate refers to how many frames per second the video displays. Higher frame rates make motion smoother by increasing image updates. Standard frame rates are 24fps for film, 30fps for HD broadcasts, and 60fps for enhanced realism. Home theaters utilize fast refreshing screens to correctly reproduce frame rates in movies and television shows without stutter, judder, or blurring. Learn more: Video frames rates vs TV refresh rates
Frequency Response
Frequency response indicates how speakers or headphones reproduce different frequencies, from the lowest bass to the highest treble. It's given as a range, like 20 Hz to 20 kHz, the spectrum of human hearing. For example, subwoofers typically focus on low frequencies and might have a response of 20 Hz to 200 Hz. Bookshelf speakers, being more versatile, could range from 50 Hz to 20 kHz, while small satellite speakers might produce frequencies from 150 Hz to 20 kHz. In a home theater setup, ensuring each speaker type complements the others in frequency response is vital for a cohesive sound experience.
Front High Speakers
Front high speakers are mounted above the regular front speakers in an advanced surround sound setup. Their height adds a vertical dimension to the sound, creating an enveloping audio experience. They complement traditional front, center, and rear speakers, enhancing overhead sounds like rainfall or a helicopter's rotor. They're often a part of setups like Dolby Atmos or DTS:X.
Return to Top


Google Assistant Integration
Google Assistant Integration is where you can control a device using voice commands through Google's virtual assistant. For audio devices, this might allow you to change tracks, adjust volume, or switch inputs without touching a remote. This voice-activated functionality promotes convenience and hands-free control. It's comparable to Amazon's Alexa or Apple's Siri integrations.
Ground Loop Hum
Ground loop hum is an audible buzzing or humming noise caused by multiple devices sharing a common ground connection. It occurs when current flows between component grounds through stray wiring capacitance, which creates small differential voltages that get amplified as noise. Home theater components like Blu-ray players, receivers, televisions, and speakers share a common ground via electrical outlets, which can cause this issue. If you have a problem, you will hear the ground loop hum through your speakers, especially when it is quiet. Using isolation transformers, noise filters, or advanced grounding techniques can prevent the noise by actively breaking the ground loop.
Return to Top


HD DVD (High Definition Digital Versatile Disc)
HD DVD, or High-Definition Digital Versatile Disc, was a digital optical disc storage format developed by Toshiba to compete with Blu-ray. HD DVD provided high-definition movie content for home theaters and required specialized players. However, HD DVD eventually lost the format war to Blu-ray and ceased production in 2008. But for a time, it was a choice for consumers seeking high-definition playback in their home theater systems.
HD Ready
A TV is 'HD Ready' if it accepts and displays the minimum standard for an HD signal. The minimum requirement is that the TV can show video with 720 vertical lines and a widescreen aspect ratio. In some countries, the term also requires the TV to receive the picture via analog component or digital connections (DVI or HDMI) - a given with any modern display.
HD Ready 1080p
An HD Ready 1080p TV must exceed the criteria for an HD Ready TV. Therefore, it must have a minimum native resolution of 1920 x 1080 pixels (1080 vertical lines at a 16:9 aspect ratio), display the image without distortion (1 pixel for each pixel in the source image), and be HDCP-enabled.
HDCP (High-bandwidth Digital Content Protection)
HDCP is a digital copy protection method integrated into HDMI 2.0 specifications. It encrypts digital video and audio content sent between devices over HDMI, such as from a Blu-ray player to a TV. Both devices must be HDCP-compatible for a successful transfer. If not, the device will only receive an analog signal, preventing the creation of perfect digital copies. For 4K content, devices need HDCP 2.2 compliance. If your 4K TV and Ultra HD Blu-ray player support HDCP 2.2, but your AV receiver doesn't, the AV receiver won't transmit the 4K content.
HDMI (High-Definition Multimedia Interface)
HDMI is a standard interface for transmitting digital audio and video signals using a single cable. Modern audio-visual devices typically come equipped with at least one HDMI port. When possible, choose HDMI over older connections like Component or SCART. Using HDMI, you can send high-definition video signals and up to 8 uncompressed digital audio channels, including advanced formats like Dolby TrueHD and DTS-HD Master Audio (with HDMI 1.3). Learn more: Understanding the HDMI connector and cable
HDMI ARC (Audio Return Channel)
HDMI ARC is a feature of the HDMI specification designed to streamline home theater setups. HDMI ARC allows a television to send audio data upstream to an AV receiver or soundbar over a single HDMI cable. Therefore, an ARC connection means that when you connect devices to your TV, such as a Blu-ray player or a gaming console, you don't need a separate audio cable to send the sound from the TV to your external speakers; the HDMI cable handles both video and audio.
HDMI Audio Extractor
An HDMI audio extractor pulls the audio signal out of an HDMI connection and converts it to an analog or digital audio output, such as stereo RCA or optical S/PDIF. By extracting the sound, you can play the audio from an HDMI source through a sound system or speakers that don't have HDMI inputs.
HDMI eARC (enhanced Audio Return Channel)
HDMI eARC is an enhanced version of HDMI ARC, introduced with HDMI 2.1. It provides better bandwidth, allowing for higher-quality audio formats, such as uncompressed Dolby TrueHD and DTS-HD Master Audio.
HDMI Matrix
An HDMI matrix combines the functionality of a splitter (sending one input to multiple outputs) and a switch (routing multiple inputs to a single output) into one device, allowing full flexible routing of any input source to any display on demand. HDMI matrices provide simultaneous splitting and switching capabilities that basic splitters and switches lack.
HDMI Splitter
An HDMI splitter takes a single HDMI input and splits it into multiple outputs that all display the same image. Splitting the signal like this lets you simultaneously send the video from one device to more than one display.
HDMI Switch
An HDMI switch allows you to connect multiple HDMI input sources (like Blu-ray players, game consoles, etc.) and switch between them to display on a single output, like a TV. It lets you toggle between different devices connected to the same display.
HDR (High Dynamic Range)
HDR is a technique that increases the dynamic range of an image, resulting in darker blacks, brighter whites and more colors. So, HDR produces more lifelike images. There are different versions of HDR, such as HDR10, HDR10+, Hybrid Log-Gamma and Dolby Vision. Your complete hardware chain (player, receiver, TV or projector) must support a particular version for it to work.
HDR10 is an open-source format of HDR supported by several hardware manufacturers. Currently, HDR10 is the most common version available on sources and displays.
HDR10+ is an updated version of HDR10. Like Dolby Vision, it supports dynamic metadata, which can change each frame's brightness and color range. It is becoming more common in some manufacturer's products.
HDTV (High-Definition Television)
HDTV produces images with much higher resolutions than the previous standards of SDTV and EDTV. To be called a high-definition picture, each video signal frame must have a minimum of 720 vertical lines of information with progressive scan or 1080 vertical lines with interlaced scan. Therefore, 720p or 1080i are both high-definition signals as well as the big daddy - 1080p (also known as full HD). The picture should also have a 16:9 aspect ratio (widescreen).
HEOS is a wireless multi-room sound system developed by Denon. With HEOS-compatible devices, you can stream music throughout your home, controlling everything via the HEOS app. Using multi-room speakers means you can play music in one room or synchronize it across multiple rooms. A similar system would be Sonos or Yamaha's MusicCast.
Hertz (Hz)
Hertz (Hz) is the unit used to measure frequency. For sound waves, it tells you how many cycles per second a waveform completes and indicates pitch: a lower Hz value corresponds to a bass sound, while a higher value is treble. It's essential to know this when looking at a speaker or headphone frequency response chart. For context, human hearing typically ranges from 20 Hz to 20,000 Hz (20 kHz).
High-resolution Audio
High-resolution audio refers to sound formats and technologies that surpass the quality of standard audio CDs. While CD quality is 44.1 kHz with a 16-bit depth, high-res audio typically starts at 48 kHz/24-bit and goes much higher. High-resolution audio formats give more clarity and detail than those with lower sample rates. However, you need a high-quality sound system or headphones to hear the difference, so it's not something everyone will appreciate. Popular high-res formats include FLAC and ALAC, which retain all the audio detail without the compression losses found in some other lossy formats.
HLG (Hybrid Log-Gamma)
HLG is a high dynamic range (HDR) format co-developed by the BBC and NHK in Japan. Unlike other HDR formats, HLG is designed for live broadcasting, making it ideal for watching live sports or events in a home theater setup. When a television or projector in a home theater supports HLG, it can display this content with richer colors and better contrast, elevating the viewing experience.
Home Cinema / Home Theater
A home cinema, often called a home theater, is a home setup replicating a commercial cinema experience. It typically includes a large-screen TV or projector, surround sound speakers, and sources like Blu-ray players or streaming devices.
Return to Top


Image Processing
Image processing in a projector refers to the various techniques used to enhance the picture quality of the projected image. These techniques can include adjusting the color, contrast, sharpness, and other elements of the image to improve its clarity and overall appearance. Image processing aims to produce a clear, vibrant, and realistic picture on the screen, which can significantly enhance the viewing experience. Consider the image processing features of a projector before buying if you like to fine-tune what you see.
Image Resolution (Video Resolution)
Image resolution, or video resolution, refers to the number of pixels used to create a digital picture measured by pixel columns horizontally and rows vertically. Higher resolutions have more pixels and provide more detail, sharper images, and smoother text. Full HD 1080p uses 1920 x 1080 pixels, while 4K Ultra HD jumps to 3840 x 2160 pixels for even crisper image quality. Matching the video resolution with the native resolution of the display ensures clear, highly detailed images without blurriness or excessive processing.
IMAX Enhanced
IMAX Enhanced is a certification for home entertainment products, ensuring they deliver a high-quality audio-visual experience reminiscent of IMAX theaters. Products with this label have met stringent performance standards, giving you sharper images and immersive sound. It's comparable to THX certification, another standard for audio-visual excellence.
Impedance, measured in ohms, describes how much resistance a speaker or headphone presents to an audio signal. In simpler terms, it's how hard the amplifier has to work to drive them. Typical values are 8 or 6 ohms for speakers designed for the home. Matching the impedance between your speakers and amplifier is crucial for efficient power transfer and sound quality.
Impedance Switching
Impedance switching allows amplifiers or receivers to adjust to different speaker impedances. This feature ensures the amplifier provides the correct power for the connected speaker's resistance, optimizing performance. You can avoid issues like overheating or distortion by toggling this switch, which may occur with impedance mismatches. However, changing to a lower setting may also degrade the amplifier's performance.
Infrared (IR) Repeaters
Infrared repeaters are devices that extend the range of infrared remote control signals. They are helpful if your home theater equipment is behind closed doors or walls. In that case, an IR repeater can relay your remote's commands, ensuring everything works seamlessly. Essentially, it captures the remote's signal, amplifies it, and re-emits it, allowing for remote operation even without direct line-of-sight.
Input Ports
Input ports on a TV, AV receiver or projector are the physical connections that allow you to connect different devices, such as a laptop, gaming console, or Blu-ray player. The most common input ports are HDMI, optical audio, VGA, and USB. However, other types of ports may also be available, like component and composite video. The more input ports a device has, the more devices you can connect to it simultaneously, making it more versatile and convenient to use.
Interlaced Video
Interlaced video doubles the video frame rate without needing more bandwidth. Old CRT TVs use this method by constructing each image frame in two steps down the screen. First, the TV fills the odd lines - 1, 3, 5, 7, etc. Next, it starts from the top and fills the even lines - 2, 4, 6, 8, etc. After these steps, the TV completes one image frame. We call each step a 'field.' The TV then continues this process for subsequent frames. Old PAL and NTSC TV signals traditionally use interlaced video, sometimes resulting in flickering and unclear images. But, modern screens prefer progressive scan images, so current AV products convert, or deinterlace, interlaced video sources before display.
Internet Radio
Internet radio, unlike traditional radio, streams over the internet, offering a vast selection of stations worldwide. Internet transmission means access to various genres, languages, and themes without geographical location or radio wave strength constraints. Devices with internet radio capabilities, like AV receivers and media players, connect directly to these stations, offering a broader choice than standard FM/AM radio.
IP Control
IP control allows you to manage devices in a home theater via internet protocol, typically over a local network. This control often integrates with home automation systems, letting you operate your audio-visual equipment through apps or centralized interfaces. It's a step beyond traditional remote controls, offering flexibility and integration possibilities. The RS-232 control port is an alternative standard remote control method for mid to high-end AV receivers used in professional installations.
IR (Infrared)
IR is a type of electromagnetic radiation commonly used to send control signals to household electronic devices using a remote control. Infrared remote controls need 'line-of-sight' with the device they control, i.e., they won't work through walls or doors.
ISF Calibration
ISF calibration, endorsed by the Imaging Science Foundation, ensures that your TV or projector displays colors and images as intended. Professional calibrators, using specialized tools, adjust the settings of your display for optimal picture quality. Professional calibration guarantees accurate colors and black levels, ensuring a more authentic viewing experience. It can be expensive to hire an ISF calibrator. But it will ensure you get the best performance from your costly TV or projector.
Return to Top


Jitter refers to tiny, unpredictable variations in a digital signal's timing. In audio, jitter can lead to distortion or a degradation in sound quality. High-quality DACs (digital-to-analog converters) and other audio equipment often have measures to minimize jitter, ensuring more precise audio reproduction.
Judder is the uneven motion or jerky appearance you sometimes notice in moving objects or scenes during panning shots in movies. Judder often arises due to a mismatch between the frame rate of the film and the refresh rate of the TV or projector. For example, most movies use 24 frames per second (fps), but many TVs have refresh rates of 60 Hz or more. The difference between these rates can cause the image to judder. Modern TVs may include specialized processing modes like' film mode' or '24p mode' that adjust the TV's refresh rate to match the movie. Other methods use techniques like 3:2 pulldown, which repeats certain film frames in a specific pattern to match the frame and refresh rate.
Return to Top


Keystone Correction
Keystone correction is a feature in projectors that helps to fix the distortion that occurs when the projector is not placed directly in front of the screen or is tilted upwards or downwards. It adjusts the image to make it rectangular and proportional to the screen. This feature is useful when there is limited space to position the projector or the screen is at a different height than the projector. Keystone correction can be done manually or automatically through the projector's settings.
Kilohertz (kHz)
Kilohertz (kHz) represents a unit of frequency equal to 1,000 cycles per second. Speakers, receivers, and other audio equipment often have specifications measured in kHz, indicating the range and capabilities of the device to reproduce specific audio frequencies. For example, the frequency response of a bookshelf speaker might be 50Hz-25kHz.
Return to Top


Lamp Life
Lamp life indicates how many hours a projector's light source will last before needing replacement. Quality lamps in well-maintained projectors can operate for thousands of hours without dimming or distortion. Cheaper lamps degrade faster, producing gradually worsening image brightness and color accuracy. Keeping track of a projector's lamp life in the settings menu is vital, as a failing lamp can lead to dimming, color distortion, or even complete failure. Before buying a projector, consider the expected lamp life to ensure you won't have to change expensive bulbs frequently.
Latency is the delay between sending an audio signal and hearing it. Latency is crucial when syncing audio with video, ensuring dialogue matches on-screen lip movements. Wireless audio devices, like Bluetooth headphones, might have perceptible latency, but technological advances are continually reducing this delay. AV devices like TVs, Blu-ray players and AV receivers often have a lip sync audio setting to minimize the delay if it is a problem.
LCD Projector
LCD stands for Liquid Crystal Display, a technology some projectors use to create images. LCD projectors shine a bright light source through panels containing millions of liquid crystal pixels. Each tiny pixel manipulates the light passing through, producing different colors and shades. LCD controls light efficiently to generate bright, vivid images with excellent color accuracy. Fast response times also make LCD technology well-suited for gaming and motion video. An LCD's brightness, clarity, and speed produce realistic projected images.
LCD TV (Liquid Crystal Display Television)
An LCD TV uses liquid crystals sandwiched between two layers of polarizing material to produce images on the screen. LCD TVs became popular for displaying content due to their slim design, energy efficiency, and ability to produce bright images, making them suitable for well-lit rooms. Recently, enhancements like LED backlighting have improved the LCD TVs' performance, making them a popular choice for a home theater.
LCoS (Liquid Crystal On Silicon)
LCoS, or Liquid Crystal On Silicon, is a display technology that uses liquid crystal layers placed on top of a silicon backplane. LCoS is often found in high-end projectors due to its ability to deliver sharp, high-resolution images with good color accuracy and less visible pixel structure than many other projection technologies. LCoS is similar to DLP projection technology, which uses mirrors rather than coated silicon chips.
LED TV (Light Emitting Diode Television)
An LED TV uses LEDs for backlighting the display instead of traditional cold cathode fluorescent lamps (CCFLs). LED TVs are popular because they offer a thinner profile, greater energy efficiency, and a longer lifespan than their CCFL counterparts. Additionally, some LED TVs provide more precise color and brightness control, especially those with local dimming features, enhancing the viewing experience in home theater environments. Learn more: How to pick the best flat screen TV
Lens Memory
Lens memory is a feature in some high-end projectors, allowing users to save different zoom and focus settings for various aspect ratios and screen sizes. With lens memory, users can easily switch between different aspect ratios (such as 16:9 and 2.35:1) without manually adjusting the zoom and focus every time. This feature is handy for home theater enthusiasts who regularly play content with different aspect ratios.
Lens Shift
Lens shift refers to a projector's ability to adjust the lens's position and move the projected image up, down, left or right. This movement allows you to place the projector off-center and still cast a straight, aligned image onto the screen. Lens shifting avoids keystone distortion or other image distortions caused by projecting at an angle.
Letterboxing is caused by displaying a widescreen image on a screen with a different aspect ratio, resulting in black bars appearing at the top and bottom of the image. The bars ensure the image appears in its correct aspect ratio without being stretched or distorted. For example, suppose you watch a 16:9 widescreen movie on a traditional 4:3 aspect ratio projector or TV screen. In that case, black bars will appear at the top and bottom of the screen to maintain the original widescreen aspect ratio of the movie.
LFE (Low-Frequency Effects)
The LFE is an optional low-frequency (below 120 Hz) audio channel designed explicitly for sounds like explosions, thunder, or other low-frequency movie effects. It is commonly associated with the '.1' in a surround sound setup, such as 5.1 or 7.1. The LFE channel is typically played through a subwoofer to provide a rich, immersive cinematic experience. However, if you don't have a subwoofer installed, the AV receiver can send the LFE track to full-range speakers instead. Learn more: How to connect a subwoofer
Line Level
Line level describes the strength of an audio signal, measured in decibels against a reference voltage. It differs from other signal levels like mic level, which is the voltage generated by microphones. In most audio equipment, there are two primary standards for line level: consumer equipment typically outputs at -10 dBV, while professional gear often operates at +4 dBu. However, this signal isn't strong enough to drive speakers directly. Hence, you must connect your CD or Blu-ray player to an amplifier to hear the audio.
Line Out
The 'Line Out' is an audio output that sends a fixed audio level, which means its volume isn't controlled by the device it's coming from. AV receivers commonly use a line out for sending a stereo audio source to a different zone. You wire the stereo RCA line out connectors to an integrated amplifier in a separate area of your home, which would control the volume and power the speakers.
Lip Sync
Lip sync, or lip synchronization, matches spoken words to the movement of a speaker's lips on the screen. It can be distracting if audio and video are out of sync in a home theater. Many modern receivers and TVs offer a lip sync adjustment feature, allowing users to correct misalignment. HDMI eARC connections have an automatic lip sync feature, which can help prevent lip sync issues.
Lossless and Lossy Compression
Lossless and lossy compression are methods of reducing audio file size. Lossless, as the name implies, retains all the original audio data, ensuring high-quality playback, seen in formats like FLAC, ALAC, Dolby TrueHD and DTS-HD Master Audio. Lossy, such as MP3, AAC, DTS and Dolby Digital, remove some data to achieve smaller sizes but will reduce audio quality. The choice between them is often a balance of quality and storage needs.
Loudness Compensation
Loudness compensation adjusts audio frequencies to make low-volume playback sound fuller. Our ears perceive frequencies differently at lower volumes, often losing bass or treble nuances. Loudness compensation on audio equipment ensures a consistent sound experience across varying volume levels. Many AV receivers have advanced loudness compensation algorithms that help balance the sound when played at low levels. Some examples are Dynamic EQ (Audyssey) and YPAO Volume (Yamaha).
LPCM (Linear Pulse Code Modulation)
LPCM is a method used to represent analog audio signals digitally. LPCM is a standard audio format found on Blu-ray discs, DVDs, and CDs. Since it provides uncompressed audio data, LPCM delivers high-fidelity sound quality, making it a good choice for enthusiasts when other lossless audio formats like Dolby TrueHD aren't available. In home theater or consumer audio discussions, people often use 'LPCM' and 'PCM' interchangeably. Although they are technically different, they are essentially the same thing.
Return to Top


Marantz HDAM (Hyper Dynamic Amplifier Module)
Marantz's HDAM is a discrete circuitry design used in their high-end audio equipment. It replaces standard integrated circuits, aiming for faster signal speeds and more dynamic, detailed sound. HDAM technology is one of the features contributing to its renowned audio quality.
MCACC (Multichannel Acoustic Calibration System)
MCACC, developed by Pioneer, is an auto-calibration system for home theaters. By analyzing your room with a provided microphone, it adjusts speaker size, level, and distance settings to optimize audio performance. Like other calibration systems, such as Audyssey MultEQ or YPAO, its goal is to tailor audio output to your specific environment.
MHL (Mobile High-Definition Link)
MHL is a technology that allows you to connect mobile devices, like smartphones or tablets, to high-definition displays, like TVs, using a cable. You can enjoy videos, games, or photos on a larger screen through MHL while charging your device. MHL allows up to 1080p HD video transfer, supports HDCP copy protection and uses a standard Micro-USB (or USB-C) cable to connect the mobile device to an MHL-compatible display or TV.
Midrange refers to the audio frequencies between the bass and treble portions of the sound spectrum. While there is no exact definition, the midrange is around 250 Hz to 4 kHz, with low mid-range from 250 to 500 Hz and high midrange from 2 kHz to 4 kHz. In a movie soundtrack, the midrange is crucial as it predominantly carries vocals, dialogues, and many musical instruments, ensuring clarity and depth. A well-balanced midrange contributes significantly to an immersive and realistic audio experience in any home theater setup.
A monoblock is a type of amplifier dedicated to powering a single audio channel. Home theater enthusiasts often use monoblock amplifiers for each speaker to ensure maximum power and audio fidelity. This approach allows each speaker in a multichannel setup to receive dedicated amplification, resulting in clearer, more detailed sound and minimizing potential interference between channels.
Monolithic Amplifier
A monolithic amplifier packs all the components of an amplifier circuit into a tiny integrated chip built on semiconductor material. This specialized construction allows monolithic amps to boost audio signals across a wide frequency range while lowering distortion. Their compact size makes monolithic amplifiers useful for quality stereo equipment, surround sound receivers, and other home audio applications needing robust amplification. Audiophiles like monolithic amplifiers for their ability to reproduce clean, accurate sound without interference or noise.
MQA (Master Quality Authenticated)
MQA is an audio codec developed by Meridian Audio for high-res audio streaming. It is a lossless compression technique that reduces high-resolution audio file sizes by around 50%, with no perceptible loss in quality. When played on MQA-compatible devices, listeners can enjoy music as the artist intended. It's become popular on streaming services like TIDAL and has been adopted by consumer electronics brands like Onkyo and Pioneer.
Multichannel Analog Outputs
Multichannel analog outputs on audio equipment allow for the connection of multiple speakers via individual channels. This feature is crucial for setups like 5.1 or 7.1 surround sound systems, where each speaker receives a unique audio feed, and a digital connection isn't possible. Audiophiles often prefer the sound from the analog multichannel outputs of high-end AV gear to a digital HDMI or optical audio connection.
Multichannel Audio
Multichannel audio describes a sound system that uses multiple audio channels or speakers to create an immersive sound environment. Multichannel audio setups, like 5.1 or 7.1, use various speakers around the room to produce sound from different directions, enhancing the viewer's experience by making movies and shows feel more lifelike and engaging.
Multichannel Stereo
Multichannel stereo mode plays stereo sound, typically from two channels, through multiple speakers in a surround sound setup. Instead of producing unique sounds for each speaker, multichannel stereo replicates the same sound, creating an enveloping but not directional audio experience. It helps fill a room with sound without using surround audio, like when entertaining guests.
MusicCast Surround
MusicCast Surround is a Yamaha technology that enables wireless rear speakers and subwoofer connections in a home theater system. With compatible Yamaha devices, you can reduce cable clutter and easily set up a surround sound experience. It's a part of Yamaha's broader MusicCast system, which covers multi-room audio solutions.
Return to Top


NanoCell is a term used by LG to brand its top-of-the-range LED TVs. NanoCell TVs use a similar LED technology to QLED TVs. Therefore, they have an increased color range and better viewing angles than standard LED TVs.
Native Resolution (Display Resolution)
The native resolution, also called the display resolution, is the fixed number of pixels a display device contains, like a TV, monitor, or projector. People also refer to it as the pixel dimension. You express the native resolution by counting the number of horizontal pixels followed by the number of vertical pixels. For example, a screen with a native resolution of 1920 x 1080 has 1920 pixels across and 1080 pixels down. Generally, a screen with more pixels offers a sharper image. A display's native resolution doesn't change and is not the same as the image resolution.
NTSC (National Television System Committee)
NTSC is a color television broadcast standard. NTSC was the primary analog television system used in North America, Central and South America, and other countries. Old home theater equipment, like DVD players and older TVs in these regions, were designed to be compatible with the NTSC standard. Digital broadcasting has largely replaced NTSC, but it remains important for compatibility with legacy equipment and media. NTSC is often used to describe a 480i picture. However, this is misleading as NTSC is an analog TV standard, whereas 480i is a type of digital video.
Return to Top


Object-based Audio
Object-based audio is a mixing technique where individual sound elements (or 'objects') are spatially mapped and independently placed and moved within a 3D soundstage. Unlike traditional channel-based audio, where sounds are mixed to specific channels (like left, right, center), object-based audio allows for a more dynamic and precise localization of sounds in a 3D space. Systems like Dolby Atmos, DTS:X, and Auro-3D utilize object-based audio, offering an immersive audio experience by allowing sound to emanate from all around the listener, including overhead. In home theaters, this often translates to setups with height or ceiling speakers to reproduce the vertical dimension of the soundstage.
OLED televisions use Organic Light-Emitting Diodes (OLED) to display images. OLED screens offer superior contrast ratios and faster response times than traditional LED TVs. This technology allows for deeper blacks, more vibrant colors and excellent viewing angles, enhancing the visual experience for viewers. Additionally, OLED TVs can be incredibly thin and flexible, leading to sleeker designs and potentially curved screens, making them a popular choice for high-end home theater setups. Learn more: How to pick the best flat screen TV
Optical Audio Connection
An optical audio connection, known as TOSLINK (Toshiba Link), transmits digital audio signals using light. An optical connection provides a way to send high-quality audio from a source device, like a Blu-ray player or game console, to a receiver or soundbar without interference from electronic noise, ensuring clean and clear sound reproduction. Optical audio supports uncompressed stereo audio and Dolby Digital/DTS 5.1 surround sound audio signals. Learn more: Optical digital audio explained
Overscan is a technique where a television enlarges the picture slightly, cutting off the outer edges. Using overscan ensures the entire screen displays images without unwanted artifacts or transmission signals. While it was more common with older standard-definition TVs to compensate for edge inconsistencies, many modern HDTVs and projectors allow users to toggle overscan on or off. Turning off overscan for high-definition and UHD content can provide a more accurate, edge-to-edge viewing experience.
Return to Top


PAL (Phase Alternating Line)
PAL (Phase Alternating Line) is a color encoding system for analog television broadcasts, which digital transmissions have largely replaced. PAL was the standard used in many countries outside North America (which used NTSC), including parts of Europe, Asia, and Africa. PAL often describes a 576i picture (with 625 lines and a 50 Hz refresh rate).
Passive Radiator
A passive radiator is a type of driver used in speakers to enhance low-frequency or bass performance. It is a diaphragm, like a regular speaker driver, but lacks the magnet and coil. The passive radiator moves in response to the changes in air pressure inside the cabinet. By doing so, it can enhance the bass response of a speaker without using more power. It's an alternative to traditional bass ports, providing depth to the sound, especially in smaller speaker designs.
Passive Speakers
Passive speakers require an external power source, like an amplifier, to produce sound. They don't have built-in amplification, making them lighter and sometimes more versatile for pairing with different amplifiers. Active or powered speakers, in contrast, have built-in amplifiers and only need a power source.
Passive Subwoofer
A passive subwoofer requires an external amplifier to produce sound. Unlike its active counterpart, which has a built-in amplifier, a passive sub relies on the home theater's main amplifier or a separate one for its power, making it essential to ensure compatibility in terms of power and impedance. Generally, passive subwoofers won't have inbuilt volume and tone controls, as the amplifier will do this before sending the signal to the subwoofer. Most subwoofers designed for home cinema will be active models.
A passthrough allows an audio or video signal to pass through a device without altering it. For example, a receiver might have a 4K passthrough, meaning it can relay a 4K signal from a source to a TV without downscaling it. This feature ensures that high-quality signals maintain their integrity throughout your equipment chain. Conversely, if a receiver doesn't have a passthrough for a particular feature, like HDR10+ or Dolby Vision, you won't be able to use it for that purpose.
PCM (Pulse-Code Modulation)
PCM is a method to digitally represent analog signals, commonly used in audio CDs and digital audio formats. It samples the amplitude of the analog signal at uniform intervals. Then, it quantizes each sample to the nearest value within a range. A typical sampling rate is 44.1 kHz for CD audio with a bit depth of 16-bit. You may also see Linear Pulse-Code Modulation (LPCM) in home theater audio. LPCM is a specific type of PCM with a defined set of sampling rates. However, for the end user, it is essentially the same thing.
Phantom Center Channel
In audio setups without a dedicated center channel speaker, a phantom center channel is created using the left and right speakers. They produce the sound meant for the center, creating the illusion of a sound source in the middle. It's a technique used when space or equipment constraints prevent installing an actual center speaker.
Phono Input
A phono input connects a turntable to an amplifier or receiver. It has a built-in preamplifier, boosting the typically weak signal from vinyl records to a level suitable for playback. For audiophiles with vinyl collections, a phono input is a crucial feature to look for in audio equipment. Many AV receivers have a phono input on the back. However, it is an optional feature, so don't assume every receiver will have one. You can buy a standalone phono preamp if your receiver doesn't have one.
Picture-in-Picture (PiP)
Picture-in-Picture is a feature that simultaneously displays two different images or video sources on the same screen. It is like having two separate windows or screens overlaid on each other, one smaller than the other. PiP can be helpful for presentations, gaming, or watching multiple video sources simultaneously. It's not a common feature, but some TVs and projectors have a built-in PiP feature, so look out for this if you think it's something you'll need.
Pink Noise
Pink noise is a noise signal in which each octave contains equal energy. Unlike white noise, which has equal energy per frequency, pink noise has more energy at lower frequencies, compensating for the human ear's lower sensitivity to bass. Pink noise is commonly used for speaker calibration and room acoustics analysis. Calibration equipment can measure and adjust each speaker's output by playing pink noise through each speaker individually to ensure consistent sound levels and quality across the entire audio spectrum.
A pixel, short for 'picture element,' is the smallest individual unit of a digital image or display. Each pixel can display various colors and brightness levels, and when viewed from a distance, you will see a complete picture made from thousands of pixels. You will see the individual pixels at work if you get very close to your television. The more pixels a screen or image has, typically indicated by its resolution (like 1080p or 4K), the more detailed and clearer the displayed picture will be. The total number of pixels that make up your TV screen is the native resolution.
Pixel Shift
Pixel shift is a technology used by some projectors to enhance the resolution of the projected image. It works by rapidly shifting the position of pixels in a diagonal direction by a small distance, creating a higher-resolution image than the projector's native resolution. Pixel shift can result in a clearer and more detailed picture.
Plasma TV
A plasma TV uses small gas cells charged by precise electrical voltages to create a picture. Plasma televisions were favored for their deep blacks, wide viewing angles, and high-quality motion handling, making them popular among movie enthusiasts and sports fans. However, with the rise of OLED and LED TVs, all manufacturers have discontinued plasma TVs.
Ported Subwoofer
A ported subwoofer (AKA bass reflex or vented subwoofer) is a loudspeaker enclosure that uses a specialized port or vent to improve bass performance. The port acts like a secondary speaker cone that reinforces and extends the low-frequency output from the woofer. Ported enclosures allow subwoofers to produce deeper, richer bass tones than sealed boxes. Ported subwoofer designs are popular for home theaters and music listening rooms to add powerful, booming bass impact without needing overly large speakers.
Power Handling
Power handling indicates how much power, typically in watts, a speaker can manage without damage or distortion. It provides a guideline for pairing speakers with amplifiers: you'd ideally want an amplifier that delivers power within the speaker's handling range. Exceeding this could lead to degraded sound or speaker damage.
Power Output
Power output, often in watts, indicates how much power an amplifier or receiver can deliver to connected speakers. A higher power output can drive larger speakers or fill bigger rooms with sound. Ensuring your amplifier's power output matches or slightly exceeds your speakers' power handling is essential for optimal performance.
Powered Zone 2
Powered Zone 2 refers to receivers or amplifiers that can power a second set of speakers in a different room without needing an additional amplifier. For instance, you could watch a movie in the living room and simultaneously play music on the patio - all driven by one amplifier. Some receivers have separate speaker channels just for a second zone. However, you must choose between powering zone 2 or an extra surround sound pair with most.
A preamp, or preamplifier, boosts weak audio signals to a level suitable for amplification. It's an intermediate stage between a source, like a turntable or a microphone, and an amplifier. Integrated AV receivers combine a preamp and amplifier in the same box. But standalone preamps can offer more control and better sound quality, usually connected to a separate power amp. Passive preamps select inputs and control volume, while active preamps amplify the signal.
A pre-out port on a receiver or amplifier provides a line-level signal for external amplifiers or powered speakers. It allows you to extend your system, adding more power or speakers. Pre-out connections provide a variable volume signal, meaning the sound level will change when you alter the volume on the primary amplifier. Many users will connect an AV receiver's front left and right pre-outs to a high-quality stereo amplifier, providing better sound quality for 2-channel music. A sub-out port on an AV receiver is another typical example of a pre-out, sending the LFE audio to an active subwoofer.
Progressive Scan
Progressive scan displays a video image by drawing each line sequentially, providing a smoother and clearer picture. Progressive scan offers superior image quality compared to interlaced video, especially noticeable when watching movies or playing video games, as it eliminates flicker and provides sharper details. Modern flat-screen TVs use progressive scan images and must deinterlace any older interlaced video images they receive.
Pure Direct Mode
Pure Direct Mode, found in some audio equipment, bypasses unnecessary circuitry and features to provide the cleanest, most unaltered audio signal possible. This mode minimizes potential interference and coloration for audiophiles wanting to hear music or other audio in its most authentic form.
Return to Top


QFT (Quick Frame Transport)
Quick Frame Transport (QFT) reduces the latency between a source device and display by transporting video frames faster. QFT enhances the viewer's experience, especially during interactive activities like gaming, by ensuring smoother visuals and more immediate on-screen responses to user inputs. As part of the HDMI 2.1 specification, all devices in the chain must support this for it to work.
QLED TV is a television technology that uses Quantum Dot Light Emitting Diodes. Initially developed by Samsung, Quantum dots enhance color and contrast by emitting or altering light when exposed to electricity. QLED TVs have several advantages over standard LED TVs, such as a wider color range, increased brightness and viewing angles. However, they are also more expensive. Learn more: How to pick the best flat screen TV
QMS (Quick Media Switching)
QMS, or Quick Media Switching, is a feature within the HDMI 2.1 specification. It allows instantaneous resolution or frame rate changes, eliminating the typical blackout or delay users might experience when switching between different media types. QMS ensures a smoother, more immersive viewing experience, especially when transitioning between various media sources or formats. All devices in the chain must support this for it to work.
Qobuz is a music streaming service known for its high-resolution audio offerings. Unlike some competitors, Qobuz focuses on delivering CD-quality or better audio streams, catering to audiophiles and those seeking top-tier sound quality.
Return to Top


Radio Tuner
A radio tuner is a device or feature in audio equipment that captures radio broadcasts, either AM, FM, or digital. With a tuner, users can listen to local radio stations or, in some cases, global broadcasts directly through their home audio system.
RCA Plug
An RCA plug, or phono connector, is an electrical connection type for transmitting audio and video signals. Many AV cables feature this connection, and devices like DVD players and TVs often have RCA input/output connectors. Typically, RCA connections use red and white colors for analog stereo audio signals, yellow for analog composite video signals, and red/green/blue for analog component video signals. Coaxial digital audio connections also use a single RCA connector. Learn more: Understanding the RCA plug and stereo cables
Rear Projection Television (RPT)
A Rear Projection Television uses a small projector inside the unit to project an image onto the back of the screen. While this technology was once the go-to choice for large-screen TVs, LED and OLED TVs have since taken over. One benefit of Rear Projection Televisions was their ability to deliver excellent image quality. However, they were typically bulkier than their flat-screen counterparts. The projectors inside RPTs evolved from CRT to more modern technologies like DLP, LCD, and LCoS.
Reference Level
The reference level provides a standardized loudness target for home theater calibration and movie soundtrack mixing to optimize the listening experience. The standard reference level, recommended by THX, is 85 dB SPL for a -20 dBFS pink noise test tone, measured at the center listening position with a C-weighted slow response (domestic AV receivers typically use 75 dB for the reference level). The system should also allow a 20 dB headroom for peaks on the main channels. At this calibrated level, loud sound effects in movies peak at 105 dB SPL in any full-range channels and 115 dB for the LFE channel. Typical dialogue is around 75-80 dB. After calibration, most AV receivers output reference level at master volume 0. However, this is often too loud for the average home theater.
Refresh Rate
Refresh rate refers to the number of times per second a TV or monitor updates its screen. A higher refresh rate can result in smoother motion, especially for action movies or sports. Until recently, the standard refresh rate for a TV was 50 or 60 Hz, depending on where you are. However, modern screens now support native refresh rates of 100 or 120 Hz, which benefits UHD screens with HDR pictures. Some models claim even higher refresh rates by using digital signal processing. But these inflated numbers aren't the actual refresh rate of the television. Learn more: TV refresh rates explained
RF Remote (Radio Frequency Remote)
RF, or radio frequency, refers to the range of electromagnetic wave frequencies used for wireless communication. Home theater enthusiasts often prefer RF remote controls to infrared versions because they can communicate with devices without needing a direct line of sight, making it possible to control equipment inside cabinets or in another room.
RMS (Root Mean Square)
Root Mean Square (RMS) is a statistical measure of something that varies over time. In amplifiers and speakers, we use RMS to determine the average power output in watts. We obtain an average power value by multiplying voltage and watts RMS values. Rather than using peak power, average RMS power offers a more realistic insight into an amplifier or speaker's real-world performance and makes matching them easier. Learn more: AV receiver power ratings explained
Room Correction
Room correction is a technology that adjusts audio output based on the unique acoustics of a room. Most AV receivers have automatic systems like Audyssey (Denon and Marantz), MCACC (Pioneer), or YPAO (Yamaha) to tailor the audio output for optimal listening. These systems use a microphone to measure sound reflections, delays, and other factors before adjusting the equalization and timing of the sound. Room correction is essential for getting the best sound in your room, especially for fixing muddy and boomy low frequencies. However, some enthusiasts prefer making manual measurements and adjustments and applying acoustic treatment to control the room's sound rather than using the system supplied with the amplifier.
Roon Ready
'Roon Ready' devices are certified to be compatible with the Roon music playback and management system. Roon offers a rich, interconnected music experience, pulling in reviews, lyrics, and other content. Roon Ready devices ensure seamless integration and high-quality audio playback with this ecosystem.
RS-232 Control
RS-232 is a standard for serial communication in high-end AV receivers and other electronic devices. It provides a wired method of control, typically employing a 9-pin connector. You can use RS-232 in a home theater to integrate with control systems to manage device settings, power, volume, and more. An alternative for device management in modern setups is IP control, which offers wireless control and integration over a home network.
Return to Top


S/PDIF (Sony/Philips Digital Interface)
S/PDIF is a digital audio standard for transmitting digital signals between devices via coaxial cable or optical fiber (TOSLINK). It allows the transmission of two channels of uncompressed PCM audio or compressed 5.1 Dolby Digital or DTS. S/PDIF was developed jointly by Sony and Phillips in the early 1980s to standardize the connection between consumer audio components. While HDMI has replaced coaxial and optical as the most versatile option for sending digital audio, S/PDIF is still commonly used to connect CD/DVD players, AV receivers, gaming consoles, sound cards and DACs.
SACD (Super Audio Compact Disc)
Sony and Philips developed SACD as a high-resolution audio format to surpass the audio quality of traditional CDs. Unlike the standard CD, SACD uses a high-density disc similar to a DVD, allowing for a significantly higher sampling rate. This enhanced sampling rate provides recordings with a broader frequency response and an expanded dynamic range. Additionally, SACD supports stereo and multichannel audio, offering a richer listening experience.
SCART is a 21-pin analog connector that integrates video and audio signals. People in Europe commonly used SCART in the home to connect various components like DVD players, VCRs, or televisions before the rise of HDMI and other digital connectors. Its multiple-pin design allows it to carry composite, S-video, RGB video signals, and stereo audio, making it versatile for its time.
Screen Gain
Screen gain is the amount of light a projector screen reflects compared to a flat white surface. A higher screen gain reflects more light at the viewer, resulting in a brighter and more vibrant image. A high screen gain can be handy in rooms with plenty of ambient light, which may otherwise wash out the projected image. However, higher screen gain may also result in more visible texture or "hot spotting" on the screen, so it may not be suitable for all viewing environments.
SDR (Standard Dynamic Range)
SDR, or Standard Dynamic Range, is the traditional range of brightness and color displayed by most screens and content. TVs and content used SDR before the advent of HDR (High Dynamic Range) technologies, which deliver brighter highlights and richer colors. An older SDR TV cannot display the increased brightness, contrast ratio and color gamut required to display HDR video.
SDTV (Standard Definition Television)
SDTV, or Standard Definition Television, is any TV transmission with a lower resolution than Enhanced Definition Television (EDTV) or High Definition Television (HDTV). SDTV displays video at a resolution of 480i (in NTSC regions) or 576i (in PAL regions), offering fewer details and clarity than HD or Ultra HD televisions.
Sealed Subwoofer
A sealed subwoofer (AKA closed box or acoustic suspension subwoofer) uses a wholly enclosed speaker cabinet with no ports or vents. The airtight design provides accurate, well-controlled bass reproduction with a flat frequency response. While not as loud or boomy as ported subs, sealed subs offer tight and precise bass, ideal for home theater and music. Their compact size makes sealed subwoofers an attractive choice when deeper bass extension from ported boxes is not required.
Shielded Cable
A shielded cable is a type of cabling that uses a protective layer to prevent electromagnetic interference (EMI) and radio frequency interference (RFI). The shielding is usually made from braided copper wires or metallic foil that wraps around the inner conductor and insulation. The shield is connected to the ground, absorbing interfering signals before reaching the inner conductor. For audio systems, this ensures that the sound signal remains pure and free from unwanted noise, which is especially crucial in setups with many electronic devices or areas with lots of potential interference.
Short Throw Projector
A short throw projector can produce a large projected image while positioned very close to the screen or wall, usually less than 4 feet away. The specialized lens requires less distance to spread light for a given screen size than a standard projector. Short throw models are ideal for smaller rooms with limited space where you can't install a traditional standard throw projector. Their extreme wide-angle projection capabilities are perfect for large images in tight spaces. If you want to install a projector even closer, consider an ultra-short throw projector.
Signal-to-noise Ratio (SNR)
The signal-to-noise ratio (SNR) is an engineering measurement that compares the level of an audio signal to the level of noise in the system or recording. It is calculated as the ratio of the signal power to the noise power, often expressed in decibels (dB). A higher ratio indicates less perceived noise, meaning the sound output will be cleaner and clearer. SNR specifications are provided for audio equipment like sound cards, preamps and microphones to indicate the expected noise performance. A good SNR level depends on the application, but generally, above 90 dB is good for consumer listening devices. Over 100 dB is better for home audio systems and professional equipment.
Sound Pressure Level (SPL)
Sound pressure level (SPL) measures the air pressure caused by a sound relative to a reference value. It indicates sound volume and intensity and is measured in decibels (dB SPL) on a logarithmic scale. 0 dB SPL is the threshold of human hearing at 1 kHz, and a higher SPL means it is louder. Typical conversational speech is about 60 dB SPL, while 120-130 dB SPL is the threshold of feeling pain. SPL is used to specify many audio device specifications, including microphone sensitivity and speaker output and for setting reference listening levels for audio engineering applications.
A soundbar is a compact, elongated speaker system designed to improve and enhance audio quality for televisions. In home theater setups, users often choose soundbars for their space-saving design and ease of installation, providing a more immersive audio experience than standard TV speakers. A soundbar will often use audio processing techniques to emulate the effect of surround sound without requiring extra speakers around the room. It is usually an active speaker, which means it can be connected directly to the audio output of a TV without needing an amplifier.
Speaker Sensitivity
Speaker sensitivity measures how loudly a speaker plays for a given amount of power input. Speakers with higher sensitivity produce louder sounds with the same amount of power, making them more efficient and requiring a less powerful amplifier. Speaker sensitivity ranges from about 84db (inefficient) to 100db (efficient). Learn more: Understanding speaker sensitivity and efficiency
Spotify Connect
Spotify Connect lets users stream music directly to compatible audio devices, like speakers or receivers, without using their phone or computer. Devices with Spotify Connect can access the streaming service independently, offering more seamless playback and control.
Standard Throw Projector
A standard throw projector must be quite far from the screen to project a good-sized image. The distance required for a standard throw projector is typically 1.5 to 2 times the screen's width, meaning the projector would have a throw ratio of 1.5:1 or 2:1. They are suitable for large rooms or outdoor spaces requiring a larger image size.
Standby Mode
Standby mode refers to a low-power state for electronic devices such as TVs, radios, amplifiers and other AV components when they are switched off but still plugged into the power source. While the device appears off, it still draws a small amount of power for functions like displays, remote sensors and software updates. The advantage of standby mode is it allows a device to turn on quickly when needed. However, although standby mode draws much less power than when the device is on, it still uses energy and costs money, especially when you consider all the devices on standby mode at the same time.
Stereo Imaging
Stereo imaging refers to the ability of an audio system to reproduce sound in a way that creates a spatial representation for the listener. When done well, it can make you feel like instruments or voices are coming from specific places between the two speakers, creating a more immersive listening experience. Elements in the center of the image should be equidistant between left and right speakers, while details on the left and right should be positioned accordingly. High-resolution audio formats and high-quality audio equipment can improve the sense of imaging and space compared to poor-quality content and hardware.
Stereoscopy creates the illusion of three-dimensional depth from two-dimensional images. Stereoscopy is fundamental to 3D movies and TV shows, where viewers wear special glasses that present slightly different images to each eye, simulating depth and making objects appear as if they're coming out of the screen.
Sub Out
The 'sub out' port on a receiver or amplifier connects to an active subwoofer with a coaxial audio cable. This pre-out connection sends the subwoofer a line-level signal with the LFE channel and low-frequency sounds and is usually a single RCA connector.
A subwoofer, or sub, is a specialized speaker that reproduces low-frequency audio, or bass, enhancing the depth and impact of sound in a home theater setup. When paired with other speakers, it provides a fuller and more dynamic audio experience, making movie explosions, music, and other sound effects more impactful. An active subwoofer can also improve your amplifier's performance, freeing up more power for the remaining speakers.
Subwoofer Crossover
A subwoofer crossover determines the point at which low-frequency sounds are directed to the subwoofer instead of other speakers in a system. By setting the crossover, you can ensure that the subwoofer handles the deep bass notes while other speakers take on the mid and high frequencies. A receiver's auto room calibration software usually sets the crossover when it measures the room. However, it is a good idea to double-check the settings after it has finished. The typical crossover setting for the front and center speakers is 80 to 100 Hz. In comparison, smaller satellite speakers will require a higher setting of 150 or 200 Hz. The correct value depends on the frequency response of each speaker.
SUHD (Super Ultra High Definition)
SUHD is Samsung's advanced display technology that offers enhanced brightness, color, and contrast compared to traditional UHD TVs. While the name may imply a superior resolution, it still maintains the standard 4K resolution of 3840 x 2160, similar to other 4K TVs.
Super UHD
Super UHD is LG's advanced 4K LED TV, offering enhanced color accuracy and viewing angles. Although the name implies a higher resolution, it still has the standard 4K resolution of 3840 x 2160, like other 4K TVs.
Surround Back Speakers
In advanced surround sound setups like 7.1 systems, surround back speakers are positioned behind the listener, complementing the traditional side-placed surround speakers. They add depth and dimension to audio playback, enhancing the sensation of being enveloped by sound.
Surround Sound
Surround sound is the reproduction of audio using multiple speakers around the room. Most of the audio we hear from TV or radio is stereo, i.e., the audio comes from two speakers in front of you. Surround sound is used in cinema and at home to add space and direction to the audio. For example, a 5.1 surround sound system uses six speakers. Front left and right (which is the equivalent of your stereo speakers), front center (for dialogue), surround left and right (it's behind you!) and a subwoofer (for low bass and sound effects). A 7.1 surround sound system has two more speakers at the back, and a Dolby Atmos layout creates overhead effects. Learn more: How to set up surround sound
S-Video, or Separate Video, is an analog video connection that transmits video data as two separate signals: chrominance (color) and luminance (brightness). S-Video connectors offer better image quality than composite video connectors because they separate color and brightness information. While less common in modern home theaters due to the rise of high-definition digital connections like HDMI, S-Video was once a popular choice for connecting DVD players, camcorders, and other devices to televisions. The standard connector for S-Video is a 4-pin mini-DIN cable, although sometimes you will see a 7-pin version.
Return to Top


THD (Total Harmonic Distortion)
THD (Total Harmonic Distortion) measures how much an audio system distorts a pure tone. A lower THD indicates more accurate sound reproduction in a sound system or the quality of a power supply. When you play a pure sine wave (like 1 kHz), the output should just be that pure tone. But amplifiers often add extra frequencies that are multiples of the original (like 2 kHz, 3 kHz, etc.). These additional frequencies are called harmonics, and they distort the tone. THD measures the power of these harmonic frequencies compared to the original frequency and is expressed as a percentage or in decibels. THD values less than 1% are a good starting point in high-fidelity audio. However, the better AV receivers will have a THD below 0.1%, with audiophile models rated at around 0.02%. For power supplies, a THD under 5% is considered acceptable.
Throw Distance
The throw distance is the length you need between the projector and the screen to display a specific image size. This distance depends on the lens used and the ideal width of the image. Knowing the throw distance is essential when purchasing a projector, as it indicates how far away you need to install it. You can calculate the throw distance by multiplying the throw ratio of a projector by the width of the image you need.
Throw Ratio
A projector's throw ratio is the relationship between projection distance and image size. It represents how many units of throw distance you need per unit of projected image width. Lower throw ratios enable you to place the projector closer to the screen. High throw ratios require more space but allow larger image sizes. When selecting a projector, match its throw ratio range to the planned screen size and room layout to ensure you can achieve the required projection distance.
THX Certification
THX certification is a set of standards that ensures high-quality audio-visual reproduction in theaters and home theaters. It was developed by THX Ltd., a company founded by George Lucas in 1983. The standards cover acoustic performance (clarity, power, noise), equipment standards (processors, amplifiers, speakers), calibration solutions (correction of room acoustics) and approved technology (using certain THX patented technologies like audio decoding and processing). Owning THX-certified equipment means getting a system designed to accurately reproduce the audio as the sound engineers intended.
Toroidal Power Supply
A toroidal power supply uses a specially shaped transformer called a toroid to convert AC to DC power. The toroid's shape helps minimize magnetic interference and allows for a more compact, efficient transformer. Toroidal supplies generate less noise and can provide very stable, clean DC voltage for audio, test equipment, and other applications needing low noise. Their efficiency and low interference make toroidal supplies ideal for demanding use cases despite their higher cost compared to standard supplies.
See optical audio connection
Transcoding in the context of home audio and home theater refers to converting audio or video from one encoding format to another, e.g., converting a FLAC file to MP3 or an MKV video file to MP4 so an older Blu-ray player can read it. Transcoding can happen in real-time, for example, when streaming media from a server, or it can also be done offline as a file conversion. There are several reasons why transcoding an audio or video file might be necessary, like to reduce file size or make a file playable on different devices. Depending on the formats involved, transcoding can sometimes lead to losing quality, so it's best to play a file natively, if possible.
A transducer is a device that turns one type of energy into another. A loudspeaker is an electroacoustic transducer because it turns electrical energy into sound.
An RF tuner receives radio frequency (RF) signals and selects a specific frequency for decoding and playback. RF tuners are found in devices like TVs or set-top boxes, allowing them to capture and display broadcasted television and radio channels. Radio tuners can select the frequencies of audio radio transmissions (FM/AM or DAB). Once received, this signal is passed to an amplifier/speaker combination to make the radio signal audible. A TV tuner can tune to the frequencies of TV transmissions and convert these to sound and picture. Originally, tuners were analog devices, but digital tuners are becoming more common to receive digital content.
A tweeter is a speaker designed to reproduce high-frequency audio sounds, typically 2 kHz to 20 kHz. Tweeters are crucial in delivering clear and crisp dialogues, musical details, and sound effects, ensuring a balanced sound. They often work with woofers, which handle lower frequencies, to produce a full audio spectrum.
Return to Top


UHD (Ultra HD)
UHD is a high-resolution video standard with more detail than high-definition video. Ultra HD video includes 4K (3840 x 2160) and 8K (7680 x 4320) formats. UHD is also known as 4K, 8K, Ultra High Definition, Ultra HD 4K, Ultra HD 8K, UHDTV, SUHD and many more. UHD images don't just have more pixels. The standard also allows for an increased dynamic range (darker blacks and whiter whites) and a wider color gamut (more colors).
Ultra-Short Throw Projector (UST)
An ultra-short throw projector can produce a large image from a very short distance from the screen or wall. Ultra-short throw projectors are becoming popular in home theaters because they can provide a sizeable cinematic image even in a small room, and you don't have to run wires everywhere. The typical throw ratio for a UST projector is less than 0.4:1. However, the specific throw ratio for a UST projector will vary depending on the model and manufacturer. A typical UST projector with a throw ratio of 0.25:1 can project a 100-inch diagonal image from just 25 inches away from the screen.
Unbalanced Cable
An unbalanced cable uses two conductors to transmit an audio signal: one for the signal and the other as a ground/shielding. Unlike balanced cables, which have separate conductors for positive and negative signals, unbalanced cables are more susceptible to noise and interference, especially over longer lengths. Examples of unbalanced connections are RCA, 1/4-inch TS (Tip-Sleeve) and TRS (tip-ring-sleeve) connectors. Because they are cheap and easy to use, unbalanced cables are often used for consumer audio equipment. However, a balanced connection is better for minimal interference and maximum signal integrity.
Uncompressed Audio
Uncompressed audio files, like WAV, PCM or FLAC, retain all the original audio data from a recording without reducing quality. They offer superior sound fidelity but have larger file sizes than compressed formats like MP3 or AAC. For example, a 3-minute song can be 5-6 MB in MP3 but 20-30 MB in PCM. While uncompressed audio files sound better than compressed versions, you will only hear the difference with good-quality equipment. Streaming services, wireless delivery and certain connection types will often limit you to compressed formats due to bandwidth restrictions.
Uniformity refers to the consistency of brightness and color across a projected image or TV picture. A picture with good uniformity will display an even and consistent image without noticeable variations in luminance or color in different screen areas. Poor uniformity can lead to distracting "hotspots" or "cold spots" in the picture, diminishing the overall viewing experience.
Upconverting involves changing a video signal from one type to another. Or, to be precise, from a 'lower quality' video signal to a 'higher quality' format. For example, you might connect a DVD player to an AV receiver with an analog component connection - but want the AV receiver to output to the display via HDMI. In this case, the AV receiver must upconvert the analog component input signal to a digital HDMI output signal. Cheaper AV receivers might not allow for any conversion of video types, while more expensive models should have more options.
UPnP (Universal Plug and Play)
UPnP is a set of network protocols allowing home network devices to share data. For home entertainment, this means a device like a TV can display pictures or play movies stored elsewhere on the network - such as on a computer or NAS (Networked Attached Storage). UPnP is easily confused with DLNA. However, the DLNA certification standard uses parts of the UPnP protocol but places stricter limits on the types of media files it supports.
Upsampling increases the sample rate of a digital audio file, like converting a digital audio signal from a lower sample rate (like 44.1 kHz) to a higher sample rate (like 96 kHz or 192 kHz). Upsampling uses mathematical interpolation to generate additional digital data points between existing samples. The theory is the increased sample rate after upsampling can relax the anti-imaging filters in DACs, potentially improving analog output quality. However, critics argue that correctly done upsampling can only maintain audio quality, as it does not add new information.
Upscaling refers to converting a lower-resolution video signal or image to a higher resolution. Upscaling aims to improve the image quality on larger or higher-resolution screens, making content appear sharper and more detailed. However, the effectiveness of upscaling can vary based on the technology and algorithms used by the device. For example, you might want to play a standard-definition 480p movie on a high-definition 1080p screen. If so, something must upscale the movie before it plays on the TV, or it will look blurred and unwatchable. In this example, the DVD player or the TV can perform the video scaling, and the best results will depend on which device has the best video scaler. Often, the TV will have a better scaler because its primary purpose is to display video. You might see this process called upconverting, but don't confuse this with upconverting! Who said this stuff was easy? 🙂
A USB DAC (digital-to-analog converter) is a device that converts digital audio into an analog signal for use with headphones, speakers, or other audio equipment. This type of DAC connects to the USB port on a computer, phone or other digital source. The idea is to bypass the computer's integrated sound card or headphone jack DAC, providing higher-quality audio conversion. USB DACs typically support high-resolution audio formats like 24-bit/192kHz or 32-bit/384kHz.
Return to Top


VESA (Video Electronics Standards Association)
VESA was formed in 1989 to establish standards for the display industry. VESA is most commonly recognized in home theater for its mounting interface standard, specifically for flat-screen televisions and monitors. The VESA mounting interface standard determines the distance between the four mounting holes on the back of a display, ensuring compatibility between screens and wall mounts. When you want to wall-mount your TV, checking the VESA measurements ensures you choose a compatible mount for the screen. Learn more: TV wall mounts buying guide
VGA Connector
A VGA connector is a traditional 15-pin D-type video connection primarily designed for connecting computers to monitors. However, VGA can also link computers or legacy video equipment to projectors or HDTVs. Unlike modern digital connectors like HDMI, VGA is an analog interface and does not transmit audio. Therefore, while it provides video to a home theater display, users need a separate audio connection. As technology has advanced, HDMI, capable of transmitting high-definition video and audio over a single cable, has predominantly replaced VGA. Learn more: Understanding VGA cables and connections
Voicing is the tonal character or sound signature of an audio device, like speakers or headphones. Manufacturers might voice a product to emphasize specific frequencies to achieve a particular sound character, like warm (boosting low frequencies), bright (emphasizing the high frequencies) or neutral (flat frequency response). A V-shaped voicing increases bass and treble while reducing the mids, providing an exciting, energetic sound. Other aspects like soundstage, imaging and dynamics also influence the sound. Listening tests to determine the preferred voicing are recommended over technical specs alone when selecting headphones or speakers.
VRR (Variable Refresh Rate)
VRR, or Variable Refresh Rate, allows a display to synchronize its refresh rate to the content's frame rate. VRR enhances the viewing experience by minimizing screen tearing and stuttering, especially during high-motion scenes or when watching content from gaming consoles that support VRR. Introduced under the HDMI 2.1 standard, VRR ensures smooth visuals and can optimize power usage. Popular examples of VRR technologies include NVIDIA's G-SYNC and AMD's FreeSync. To benefit from VRR, both the graphics card and the display must support a compatible version.
Return to Top


Watt (W)
A watt is a unit of electrical power used to measure and rate speakers and amplifiers. The watt rating is commonly measured using RMS (Root Mean Square). RMS gives continuous or average power, which is a better guide for everyday use. For an amplifier, watts specify how much power and volume an amp can deliver to speakers before distortion. For speakers, it indicates the maximum wattage a speaker can handle before damage occurs. More watts don't always mean louder or better sound; other factors, like the speaker's efficiency, also influence the sound. However, ensuring your speakers and amplifier are compatible regarding wattage is crucial for optimal performance and avoiding damage.
Wide Color Gamut
The Wide Color Gamut (WCG) is a spectrum of colors that exceeds the standard color spectrum used by conventional displays. With the introduction of the 4K Ultra HD specification, the BT.2020 standard emerged, expanding the scope of available colors. Through WCG, screens can depict a more expansive and lifelike array of colors, rendering images with heightened realism and vibrancy.
A widescreen image has a wider aspect ratio than the original 4:3 (1.33:1) standard. Typically, 'widescreen' refers to a 16:9 (1.78:1) aspect ratio, the standard for flat-screen TVs. However, filmmakers often shoot movies in even wider formats, such as 1.85:1 or 2.39:1. That's why you see black bars at the top and bottom of a film on your 16:9 TV: because the movie's original aspect ratio is wider than your TV can display. Learn more: TV aspect ratios explained
Wi-Fi Direct
Wi-Fi Direct allows devices to connect without requiring a central wireless router. For audio devices, this means you can directly stream music from a device like a smartphone to a Wi-Fi Direct compatible speaker without needing a separate network connection.
Wireless Connectivity
Wireless connectivity lets devices like projectors and amplifiers receive audio/video signals without cables. Technologies like Wi-Fi, Bluetooth, AirPlay, and Chromecast transmit signals between source devices and displays without wires. Going wireless provides greater setup flexibility and eliminates messy cables between components. It allows seamless streaming from phones, PCs, and media boxes to speakers, TVs, and projectors anywhere in a room.
A woofer is a speaker designed to reproduce low to mid-range frequencies in the audio spectrum - around 40 Hz to 1 kHz. Woofers play a crucial role in delivering the depth and richness of sound, especially for movie soundtracks, music, and special effects. A typical bookshelf speaker may have two speaker drivers - a woofer for the low frequencies and a tweeter for the high frequencies. Floorstanding speakers often have more speakers.
Return to Top


XLR Connector
An XLR connector primarily transmits balanced audio signals. In a home theater setup, XLR connectors appear in high-end audio equipment such as preamplifiers, amplifiers, and professional-grade speakers for sending and receiving audio. The XLR connection reduces noise and interference, making it a favorite choice among audiophiles and professional home theater installations.
Return to Top


YCbCr is a digital video signal format that separates brightness information (Y) from color information (Cb and Cr). This separation aids in video compression and transmission, ensuring viewers receive clear, vibrant images on their screens. Blu-ray players, digital TVs, and other video sources often process or transmit video in the YCbCr format via an HDMI or DVI interface.
YPAO (Yamaha Parametric Room Acoustic Optimizer)
YPAO is an acoustic calibration system developed by Yamaha for its range of home theater receivers. It analyzes a room's acoustics and makes automatic adjustments to optimize the audio performance. By using a provided microphone to measure test tones from different speaker locations, YPAO assesses the room size, shape, and construction to set the ideal equalization, delay, and speaker level settings. The result is a more accurate and immersive soundstage tailored to the specific environment. Alternatives provided on other brands of AV receivers are Dirac Live (Arcam, Denon, Marantz), Audyssey MultEQ (Denon, Marantz), DCAC (Sony) and AccuEQ (Onkyo).
YPbPr is a color space used to transmit analog component video signals. YPbPr component connections split the video signal into three separate channels: Y (luminance or brightness), Pb (blue minus luminance), and Pr (red minus luminance). This separation provides better picture quality compared to composite video, as it reduces color interference. Many DVD players, HDTVs, and other devices offer YPbPr connections for high-quality video transmission.
Return to Top


Zone (Multi-Zone)
A multi-zone system allows a home theater receiver to send audio and sometimes video to different areas or "zones" within a home. A multi-zone feature means enjoying a movie in the living room (Zone 1) while playing music from the same receiver in the kitchen (Zone 2) or another room. This capability enhances the versatility of a home entertainment system, enabling users to customize audio and video playback based on different rooms or preferences. Budget AV receivers will have limited zone features (or none), while high-end models often support two or three zones.
A projector's zoom controls let users resize a projected image without moving the unit. Zoom adjusts the lens's focal length to widen or narrow the beam. Manual zoom uses a dial or lever to manipulate the lens. Motorized zoom provides electronic control through remotes or on-screen menus to optimize screen size. For home theater use, look for zoom ratios between 1.3x and 1.8x. This range allows 30-80% image enlargement, providing flexibility without unnecessary maximum zoom capabilities that add cost.
Zoom Lens
A zoom lens adjusts the image size by physically zooming in or out without moving the projector. Budget or portable projectors may have fixed focus lenses with no zoom (1x). A budget zoom lens may zoom 1.1x to 1.3x, allowing a 10 to 30% enlargement. 1.3x to 1.5x allows a 30 to 50% enlargement, while higher-end home theater projectors usually offer 1.5x to 2.0x zoom (50 to 100% bigger).
Return to Top