Optical Digital Audio
- Cable and Connection Explained

Optical Digital Audio - Cable and Connection Explained
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Updated: September 05, 2019

Optical digital audio connections are a popular way to send high quality audio between devices.

You might have a number of different choices when it comes to the audio for your system, and optical is always a good choice.

So what are they exactly, and what are the advantages and disadvantages?

What Does The Optical Connector Look Like?

Optical audio connection on the rear of a media player

Optical digital audio uses a connection on your device like this one on the far right (clue - it's hiding above the word optical!)

In this example, there is an optical output, and a coaxial connection above it - as well as other connections that we're not interested in right now.

When connecting two devices together, one device will have an optical outputThis is the device sending the sound. Like your TV, for example.

The other will have an optical inputThis is the device receiving the sound. Like your amplifier.

In the picture above, the optical port has a protective 'door' which will move out of the way when you push the cable in.

Some optical ports have a protective cap over the hole which needs to be removed before you can plug in the cable. As is the case in the picture here with this optical digital audio out:

Optical audio connection with protective cap

When you remove the cap you will be able to see the bright red light from inside the device.

What Does The Optical  Audio Cable Look Like?

Optical Audio Cable

An optical audio cable looks like this.

When you insert the cable it should click into place. It is designed to fit one way only, one side is squared-off while the opposite is angled on the corners.

If you look carefully you will see that this matches the shape of the port on your device.

Optical cables used for digital audio come in a wide range of lengths, colours - and prices!

You may be tempted to buy the most expensive cable on the market because... well, it's going to sound better right?

Well, not in my opinion, no. You won't get any extra special audio by spending an extortionate amount on a cable. I would just buy a good value, well-made brand. Note the emphasis on well-made.

So, where can we go and buy an optical audio cable?

There are many choices available on Amazon, so I would just check the reviews and buy one there.

The AmazonBasics digital optical audio cable should do the job just fine - however there are other good value brands there too like this BlueRigger digital optical audio cable.

Just make sure you double-check the length of the cable you are buying and get the right size for your needs. There's nothing more annoying than buying a cable and then finding out it's too short.

Been there. Done that.

What Does an Optical Digital Audio Cable Do?

An optical digital audio connection is used to send digital audio signals between devices.

It supports stereo audio, Dolby Digital and DTS 5.1 multichannel audio for people with surround sound systems.

It does not support SACD, DVD-A or high-definition audio such as Dolby TrueHD and DTS-HD Master Audio.

Check out my home theater glossary if you don't know what these are.

When Should I Use an Optical Connection?

A common question that gets asked is, "Do I need optical audio if I have HDMI?"

If your AV equipment has an HDMI port, then in most cases it would be best to transfer the audio signals via HDMI. This is because HDMI supports all types of audio signals and you can send all the video and audio signals via one cable.

However, if you don't have HDMI as an option, then an optical audio cable is a good way to transfer the audio between devices. You will be able to hear standard stereo audio and 5.1 surround sound transmissions over an optical connection.

Some older devices with HDMI ports don't actually support the transfer of audio via HDMI. Therefore, this would be another instance where you could utilize this alternative digital interface.

Another common use for this type of connection is for connecting your TV sound to your speaker system.

If you get your TV transmissions via an internal tuner, or a smart TV app, then you might want to get the audio into your home theater speaker system.

Most modern TVs have an optical audio output for this purpose. You connect the optical audio output on the rear of your TV to an optical input on your AV receiver or amplifier.

What Else Can You Tell Me About Optical Audio?

This type of interface is often referred to as a TOSLINK port - and the interconnect a TOSLINK cable. This makes reference to the developer of this connection type, Toshiba.

In this type of connection, the digital audio signal is converted into light and transferred via a cable made from optical fiber.

Aside from an HDMI connection, there are two main methods of connecting devices to send digital audio - optical and coaxial digital audio. Both of these methods of sending digital audio are also known as S/PDIF connections.

Regardless of the connection type used, there is no difference in the actual data transferred.

You often find these two connections side-by-side on a device (as in the picture at the top of the page) - or you may get one or the other.

If you have both, the decision of which one to use will usually come down to something simple such as the type of connection you have on the other device.

How Do I Convert Optical Audio to RCA Coaxial?

One scenario you may come across is that you have an optical output on your device (a DVD player for example), but only a coaxial input on your amplifier.

How annoying is that?

Toslink Optical to Coaxial Digital Audio Converter Toslink Optical to Coaxial Digital Audio Converter

However, there is a fairly simple solution. You can buy an optical to coaxial converter like the one pictured above, which will take the optical output from your Blu-ray player and output the signal via coaxial.


The use of converters can solve many potential problems when we need to mix and match different audio  types and connections.

Can I Convert Optical Audio to Stereo Analog?

Another solution to the problem of the wrong inputs on your amplifier, would be to convert the optical digital audio to analog and connect to your amplifier using our old friend the stereo analog audio connection.

But how can I possibly do this, I hear hear you cry? Well buy a digital optical to analog RCA audio converter of course.

You can see an example of one pictured below. This device will accept either an optical or coaxial digital audio connection and output the audio as stereo analog.

It's like magic I tell you!

Digital Optical Coax to Analog RCA Audio Converter Digital Optical Coax to Analog RCA Audio Converter

What Is an Optical Audio Switch Used For?

Another potential issue you may come across is that you have a limited amount of optical inputs on your AV receiver.  

In this scenario, if you have two or three devices that you want to connect into your amplifier via an optical connection, then you can buy an optical audio switch, like the one pictured below.

SPDIF & TOSLINK Digital Optical Audio Switcher SPDIF & TOSLINK Digital Optical Audio Switcher

This little box of tricks will accept the optical audio outputs of up to three different devices, and then output them into the one input on your amplifier.

The model above comes with a remote control so you can switch between the different audio inputs.

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About Home Cinema Guide

Paul started the Home Cinema Guide to help less-experienced users get the most out of today's audio-visual technology. He has worked as a sound, lighting and audio-visual engineer for around 20 years. At home, he has spent more time than is probably healthy installing, configuring, testing, de-rigging, fixing, tweaking, re-installing again (and sometimes using) various pieces of hi-fi and home cinema equipment.

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