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A Guide to Digital Audio Out (Optical, PCM, Coaxial, etc.)

Digital audio outs can be found on a wide range of devices. In fact, it’s very likely that you’ve used them without your knowing what it was. 

Digital audio outputs can be found in smart TVs, Blu-ray players, game consoles, and similar devices. Its purpose is to transmit sound to another device, such as a soundbar or a set of speakers. They are a step above the previously used analog audio outs. The most common types are optical and coaxial. 

Digital Audio Out

The rest of this article will delve into how digital audio output works, how its types differ, and what to consider when choosing between them. I will also explain the best ways to use digital audio outputs and their alternatives.

Also read:

What Is Digital Audio Out?

A digital audio out is an output in a device that sends sound to another device, such as a set of speakers or a soundbar. Digital audio outs are often seen in Blu-ray players, smart TVs, and game consoles.

Digital audio out is something that every television owner has typically come across. It’s not some new and complex “techy” thing that will have you look through several manuals or tutorials before understanding how it works. 

To understand it, let’s start with the out in “Digital Audio Out”. These ports are called “outs” because they are specifically used to put out video or sound. Some digital audio devices can be used to send signals while others only take in signals, such as microphones. 

To get sound from a digital audio output, you would use an optical or coaxial cable to connect it to a sound device, such as a soundbar or set of speakers.

Sometimes, a digital audio output will connect to an amplifier first. This device will amplify the sound signal and send it to your speakers.

How Digital Audio Out Looks

If you look at the back of a television screen, a Blu-ray player, or a game console, you will see a bunch of circular and sometimes almost square or hexagonal ports. Among them will probably be digital audio outs.

Manufacturers go a step ahead and usually have these ports clearly labeled on the device. This will make it easy to identify where each cable goes.

There are two major types of digital audio outs: optical and coaxial audio out. We will talk about these two a little later in the article.

For now, take into account that you may find some of these outlets being referred to as just ‘audio out’ with the omission of the word ‘digital’. Audio out, also known as analog audio out,  is not the same as the digital audio out. 

What Is Analog Audio Out?

An analog audio out is an output used to transmit analog sound signals. These devices are generally connected with RCA cables. These cables are usually white and red.

The color of the connectors in RCA cables corresponds to the left and right channels. Red is used for right, and white is used for left. Yellow RCA connectors are usually reserved for video.

This also makes it easy to monitor the health of your cables. For example, you can quickly tell which of your RCA cables has a problem if you can hear sound coming from the television but cannot see the video or vice versa. 

The sound we hear with our ears comes to us in an analog form—that is, as waves of specific frequencies carried by the fluctuations in the air. Analog cables work in a similar fashion: they transmit information through waveforms produced by the voltage that’s running through the cable.

Meanwhile, digital audio is made of ones and zeroes. A computer or sound system takes this information and converts it into analog soundwaves, which tell the speakers how to produce the sound you hear.

Analog audio out styles can be found on old Blu-ray, DVDs, and TVs. They have been slowly phasing out over time, and are now uncommon.

Connecting Digital Audio Out to an Analog Sound System

If you have a TV with only digital audio outputs, you may be wondering if you can connect it to an older, analog sound system. Or perhaps it’s the other way around: you want to connect your vintage game console or old DVD player to a digital set of speakers.

You can achieve this with the help of an adapter. An analog to digital adapter will have RCA ports on one side and digital output ports on the other side, which will be used to connect directly to your digital sound device. For digital to analog converters, it’s the only way around: they will have optical and coaxial inputs and analog RCA outputs.

Some analog to digital audio converters also have an HDMI output and a headphone jack port.

If you’re looking to connect your TV, Blu-ray player, or game console to an old sound system, the PROZOR Digital to Analog Audio Converter will do the trick. It will transmit your signal without any distortion and is extremely easy to use. Just keep in mind that it needs to be powered with a USB cable and doesn’t support 5.1 sound.

If it’s the other way around—that is, if you want to connect an old DVD player or game console to a newer sound system with only digital inputs—, then the Hdiwousp Analog to Digital Audio Converter is what you need. It supports a high sampling rate and comes with a fiber optic cable.

Types of Digital Audio Out

There are two main types of digital audio cables: optical and coaxial. Consumers often confuse them—after all, they’re equally capable of transmitting high-resolution audio. They both have an advantage over analog cables: they are easier to replace if they get damaged.

Coaxial and optical have each its set of pros and cons. There’s not really a wrong answer—it’s a matter of which type has better compatibility with your devices.

For a more in-depth look, here is a breakdown of coaxial and optical audio outputs.

1. Optical Digital Audio Out

Optical Digital Audio Out
Optical Digital Audio Out (right)

Optical output transmits audio signals using light. That’s why you can often see a faint light inside transparent or translucid optical cables when they’re connected. This is a great way of telling which kind of connection you have.

Optical digital audio out dates back to the early 1980’s, when TOSHIBA designed an optical fiber cobalt with a standard connector. Their purpose was to enable CD players to transmit sound to speakers. This design still remains popular, and the cables are sometimes referred to as Toslink cables—from TOSHIBA and link.

Optical digital audio uses a laser beam to transmit audio instead of the electrical impulses used by most other cables. This comes with a set of advantages and disadvantages.  

Pros

  • Using light helps avoid picking up any distortion or noise, giving you crystal clear sound. 
  • They can be used over a longer distance without losing sound quality. A longer cable will not affect data transmission.
  • Thanks to its squared or cornered edges that way, the connector is firm and secure. It will not move after being connected. 
  • The cable design is very sophisticated and appealing to the eye. The connector is made of glass, silica, or plastic.
  • The thinness of the cable makes it easier to store in small places.
  • You will find it more frequently than coaxial in devices like televisions, Blu-ray players, and game consoles.
  • It supports both compressed and uncompressed Digital Dolby Sound and its variations.

Cons 

  • They offer a smaller bandwidth than the coaxial digital out: only 96 Khz compared to the 192Khz of coaxial.
  • The cables don’t take folds or bend very well. This can cause them to get damaged very easily.
  • It may not be possible to find an optical digital audio output on every device. 

2. Coaxial Digital Audio Out

Coaxial Digital Audio Out

Coaxial cables have a similar appearance to the RCA connectors, which are also cylindrical. Like optical, coaxial cables are used to transmit sound data. However, they do this by way of electricity as opposed to light.

Coaxial cables carry data in the form of electrical impulses. They have a maximum capacity of 10MBs per second. The copper wire that transmits the data is covered by shielding that reduces interference and signal loss.

Also read: Can I Use Coaxial Cable Instead of RCA?

Here are some of the pros and cons of using coaxial cables for your audio:

Pros

  • This connector offers up to 192 kHz of bandwidth, compared to the optical limit of 96 kHz. This makes for better sound fidelity, provided that you have a good enough sound system.
  • The wires are made of fiber. This makes them more robust and able to withstand damage compared to their optical counterpart. There is no need to worry about tight bends and curves. 
  • They have cylindrical RCA-style connectors that you can find on almost any AV device, whether it’s new or old. Optical might not be found on all devices and is more common on slightly newer ones.

Cons

  • A very long cable may make you lose sound quality. It’s best to keep the cable short to minimize signal loss.
  • The style of the connector may not be as firm as the optical digital audio out, which is squared.
  • They do not support newer functions like the Dolby Atmos and DTS X. 

Optical vs. Coaxial: A Brief Comparison

Both optical and coaxial cables do the same thing: they transmit digital audio. The difference is in how they do it. Optical uses light, while coaxial uses electrical impulses. Coaxial cables are also used for other purposes, such as for internet connection.

If you want to get the highest definition possible for your audio, I recommend going for a coaxial digital audio output. Thanks to its higher bandwidth, it tends to sound slightly better than optical cables. Coaxial cables have a bandwidth of 192 kHz, while optical offers only 96 kHz.

However, at the end of the day, it’s about which connection is more convenient for you. If your devices support optical but not all of them have coaxial inputs/outputs, then staying with optical cables will make your life easier.

Besides, you will only feel the difference in sound quality if you have a very high-quality (and expensive) sound system. If you’re working with TV speakers or a soundbar, you won’t feel any difference between coaxial and optical.

What is PCM?

PCM or Pulse Code Modulation is the process by which analog audio is converted into digital audio. PCM is used to transmit audio sound from an analog device, such as a CD or a Blu-ray, to a digital sound system.

PCM is a great option if you don’t have surround speakers or amplifiers but still want to improve the sound on our television speakers.

The process of converting these analog signals into digital data is called sampling. Some files will be more difficult to convert than others. 

How Pulse Code Modulation Works

Pulse Code Modulation lets you use up to two channels of sound. This means it’s not compatible with surround systems.

PCM transmits sound without any compression, which will improve the sound quality if you have decent speakers.

In this YouTube video, Bhupinder Tube explains the key things you need to know about PCM.

What is PCM audio
Watch this video on YouTube.

PCM only works when AV devices are connected through an HDMI cable rather than coaxial or optical. If you want to use PCM, make sure your devices support HDMI. You can further monitor and control your sound set up by going to your TV settings and switching the display audio output to PCM. 

Note that this option will not work for you if you have an output device with more than two channels. If you try it, you may experience sound loss, delay, or a complete interruption of the sound.

If you want to connect your television to an additional device, such as a speaker or home theater system, consider using Dolby Digital Sound. 

Also read: PCM vs Dolby Digital vs Passthrough – Key Differences

Dolby Digital vs. PCM

Dolby Digital is an excellent option to enhance the sound quality of your home theater, soundbar, or any device that uses more than two channels. As with PCM, make sure that your AV device is connected to an HDMI cable.

To activate DTS, go to your TV settings, unselect the PCM option, switch back to auto, and then select the Dolby Digital option. This will automatically give you access to up to five channels. 

Of course, this will only work if the content you’re watching or listening to was mixed with 5.1 audio in the first place. If it’s your usual stereo, then using DTS will not make any difference.

Overall, Dolby Digital is far more advanced and sophisticated compared to PCM. DTS is compressed, but this allows it to be free of interruption and feedback.

The main advantage of DTS over PCM comes when you’re watching a movie. Surround sound creates an immersing and enveloping experience, giving you a cinema-like feeling in the comfort of your living room.

For PCM, in some cases, the improvement over ordinary direct stereo is minimal.

HDMI vs Digital Audio Out

HDMI, short for High Definition Multimedia Interface, is often talked about when it comes to audio output in AV devices. Its functionality and features are a step above what regular digital audio out gives room for. 

The YouTube video below gives a complete comparison between HDMI and audio outs. 

Digital Coaxial vs Optical Audio Cables vs HDMI - Which one is the best for Sound Quality?
Watch this video on YouTube.

HDMI is a one-size-fits-all cable that can fill up the gaps between either the coaxial or optical outputs, while at the same time offering more. HDMI outputs are found on all modern TVs, game consoles, Blu-ray players, and computers.

The HDMI cable has a higher bandwidth compared to the other two digital audio outs. The HDMI cable also supports newer technology, such as Dolby Atmos Sound, Dolby True HD, DTS Master Audio, and DTS X, which are not supported by coaxial and optical.

Additionally, new video formats like 4K resolution and HDR are also supported by HDMI. Overall, this might be your answer if you would like the most out of your AV audio. 

HDMI has a higher bitrate than optical and coaxial, which is why it can transmit better audio quality. However, this is not the only reason why you may want to consider using it: HDMI greatly simplifies your cable management. Instead of having to find a place for separate cables for video and audio, everything comes out of a single output. Besides, since most modern devices have HDMI ports, you can be sure your sound system will be compatible with anything.

Final Thoughts

Analog audio has been phasing out for a while and has been now virtually replaced by digital audio. There are two main types of digital audio outputs: coaxial and optical. Optical cables use light to transmit sound, while coaxial cables carry data in the form of electrical signals.

HDMI cables are a more advanced alternative to coaxial and optical. It will let you get the benefits of both and will also let you use features such as Dolby Atmos, Dolby True HD, DTS Master Audio, and DTS X.