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Coaxial Digital Audio
- The Cable And Connection Explained

The coaxial digital audio cable is one of the most common methods used to transfer digital audio between devices.

However, it's not your only choice, so here we take an in depth look at coaxial audio and look at when you might use it - and why it might be the best solution for your system.

What does the coaxial connector look like?

Coaxial digital connection on the rear of an AV receiver

A coaxial digital connection on your device looks like this. You can see it here in this example on the far right, next to the optical audio inputs.

It is a single female RCA connector which is often colour-coded orange or black, but not always. It just requires one cable to transfer the signal, unlike analog stereo audio for example. The port will often be labelled as 'coaxial', but may just say something like 'digital out' or 'digital in'.

The device pictured here actually has two coaxial inputs. This is because it is an AV receiver which often have multiple inputs of different types to allow the connection of many different devices. Your device may just have one input or output - depending on whether it is designed to send or receive audio.

As with all RCA connections, it doesn't matter which way round you insert the plug, it will plug-in regardless of the orientation. It should be a tight fit though, so you may have to push firmly.

What does the coaxial digital audio cable look like?

Coaxial digital audio cable

Coaxial digital audio cables for transferring audio look like this.

They have one male RCA jack at either end, and the technical specifications say they should be rated at 75 ohms for accurate transfer of the signal.

However, in the real world many AV cables may or may not be accurately designed to be 75 ohm (whatever it may say on the packaging), and the reality is you can use pretty much any cable with RCA jacks on either end over short distances - even the cheap interconnects that come with most Hi-Fi equipment these days.

There are some people that will swear blind that a more expensive cable designed for the purpose will sound better. I disagree. You may find a more expensive cable will prove more robust and reliable (if you really must keep on unplugging and re-plugging them), but as for sounding better. Hmmm.

You can make your own choice.

What does a digital coaxial connection do?

A coaxial digital audio connection is used to send S/PDIF digital audio signals between devices.

It supports stereo audio as well as DTS and Dolby Digital 5.1/7.1 surround sound signals.

It does not support DVD-A, SACD or high-definition audio such as DTS-HD Master Audio and Dolby TrueHD, so if you want to play back this type of audio, you will probably be better of using an HDMI connection.

When should I use a coaxial connection?

The preferred method of transferring digital audio signals would usually be via an HDMI connector. The reason for this is that HDMI supports every type of audio signal available and everything can be sent through one cable - video and audio.

However, if you don't have HDMI as an option, then a coaxial digital audio cable is an excellent way to send the audio between devices. This type of connection will allow you to hear standard stereo audio and 5.1 surround sound.

A coaxial digital output is most often used when sending multichannel audio from a DVD player or computer to a home theater surround sound speaker system - or from a CD player to a stereo amplifier.

What else can you tell me about coaxial audio connections?

This type of connection uses a coaxial cable to send the digital information. It will have RCA connectors at either end, which is a common connector used in other AV connections such as component video cable.

This type of digital audio connection is also referred to as an S/PDIF signal, and there are actually two connection types which send exactly the same type of signal. One is this coaxial digital audio connection, and the other is an optical digital audio interface.

It is common to find both of these connections side-by-side on a device - or you may get one or the other. If you have both it doesn't really matter much which one you use, it may just come down to the type of connection you have on the other device.

The main advantage of using digital coaxial cables over optical audio connections is that the cabling is common and more likely to be available (you're more likely to have a phono cable lying around than an optical), and is also more robust than the thin optical cable. Apart from that the differences between the two methods are quite small.

SPDIF Audio Optical to Coaxial Bi-directional ConverterSPDIF Audio Optical to Coaxial Bi-directional Converter

If required, you can buy an optical to coaxial digital audio converter to convert one S/PDIF type into another. The one pictured above can be switched to convert from coaxial to optical and vice-versa. However, some converters will only convert from one to the other, so check carefully before you buy to make sure you get the right one that you need.


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