Optical s pdif port: What Is S/PDIF? A Basic Definition

What is SPDIF optical sound output and what is it for

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Benjamin Rosa
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22 July 2021

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The output of SPDIF optical sound o S/PDIF has generally been little used by the general public. Only the most audiophiles give it the attention it deserves, but if you are interested in a better sound quality whether it’s for the gaming or home theater experience, you’re interested in how this cable works.

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Table of Contents


Definition of SPDIF

The acronym “S/PDIF” stands for Sony / Philips Digital Interface Format: Sony and Phillips Digital Interface Format, since they are the ones who have rights to this sound output. In international terms, it is known by its IEC 958 type 95 code. SPDIF is a hardware-level protocol for the transmission of PCM-modulated digital audio signals between stereophonic devices and components, so that digital sound is sent direct to a receiver without going through a process of analogousness and another of digitization with what they avoid that it loses quality.

S / PDIF is a version of the standard AES / EBU protocol. It has been adapted for use in commercial applications, with some differences that make it less expensive to produce the final components and more accessible to home users.

Simply put, SPDIF is a fiber optic cable that allows you to connect one digital sound source to another without losing quality in between. It is a connection that is little used, and is highly undervalued by users. But that does not mean that a home user can take advantage of it despite the fact that it is almost in disuse.

How to get better sound quality

La coaxial sound output SPDIF allows to have a higher sound quality coming from the original source. This is achieved by avoiding that the sound has to be converted from digital to analog sound to pass through a jack cable, to another digital device that has to convert analog to digital sound. This in a home theater stereo works well, since less information is lost in each digital-to-analog and analog-to-digital sound conversion.

Also good for sound experts in concert solos and more high-end sound kits. As sound quality is important, whenever possible try to use this connection if the source is digital instead of running it through the jack cables to the sound interface.

But this does not mean that there is S / PDIF adapters to other connectors. For ease of use, there are jack connectors for mixing consoles, minijack for small domestic equipment, and even XLR for professional mixing consoles. Some of these converters lead to a loss of quality because an analogization is generated from the sound source to the receiver and subsequently a digitization with which a loss of quality can be seen, but they are useful if we do not have receivers.

SPDIF in the domestic market

We have mentioned that it is a relatively unused connection, but that does not mean that if we know how it works and we have the equipment, we can use it. Many televisions or sound or multimedia devices have an optical sound output, which is the SPDIF connection. Since today’s flat-panel TVs tend to skimp on speaker quality to make themselves flatter and more affordable, their sound quality becomes poor and volume is low.

Sound bars have become quite popular to solve this problem for flat televisions. Although many soundbars are simply left with a minijack connection to connect through the headphone port. We must check in the box if the indications of the sound bar include optical sound input. If so, we will be in luck and we will simply have to buy said cable.

In the case of current consoles, neither Nintendo Switch, nor Xbox series S nor PlayStation 5 have optical sound output. Xbox series X, PlayStation 4, and various Xbox One models do. It is possible that future PlayStation 5 models may include an optical audio output.

For PC users, many motherboards have such an audio output for connecting speakers and sound equipment. If you don’t have one, we can buy one. sound card with S/PDIF input and output and connect it to the motherboard in order to have the possibility of having better quality audio and with less delay for when we watch movies, series or play video games where the reaction speed and sound quality can give us certain possibilities of advantage.

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Sales and drawbacks of SPDIF


  • An better sound quality by not having to convert the sound into analog and reconvert it to digital sound, with which less information and details are lost.
  • Less delay. We already discussed it in the previous point, but since SPDIF requires fewer steps to convert sound from digital to analog and from analog to digital, fewer milliseconds are lost in the transfer.


  • If the S / PDIF cable is coaxial and not optical, it will be necessary that the cable be of quality.
  • The best sound quality is hard to prove. Because it takes so much trained sound, clean original audio, and high-quality sound equipment, we may not appreciate the quality improvement fully or at all. If the movie we are watching only has two audio channels, or if we are listening to streaming music with a data saving mode or with a slow internet connection, we will hardly notice that it sounds better.
  • Requires the right equipment. If we use a low-quality sound system, be it a motherboard that is not up to par, an almost obsolete sound card or bad speakers, it will create a bottleneck and we will not be able to hear quality sound.
  • It is in relative disuse. Since it is not a widely used connection in the home environment and is designed for the most demanding users, we may have some problems when it comes to finding televisions, motherboards, speakers, sound bars or home theater systems that do not have it. . We already commented that of the current consoles, only those of the last generation have it, and the most expensive version of the Xbox series, the Xbox series X. The PlayStation 5 does not have SPDIF output, although a future model could have it, and they never have had Nintendo consoles.

The reason for the deprecation of S / PDIF

S/PDIF has never been very widespread among mainstream audiences, and its use may not spread beyond the audiophile circle. It is difficult to appreciate its quality if, for example, the original sound does not have a very high quality with which to appreciate the different nuances of sound. There is also the need for the right equipment so as not to bottleneck sound quality. For many users, the quality provided by the minijack, jack or HDMI ports is sufficient for their audio needs, so this sound output is reserved for the most demanding and professional environments.

It is also that consoles and video games in general do not make use of high-quality audio. With the increase in bandwidth of HDMI y display portIn addition to the fact that games in general have compressed audio, you cannot appreciate that better sound quality.

Today, the best option is the consumption of multimedia audio from high-quality sources such as Blu Rays or Blu Ray 4K, or movies and series without sound compression. There are also video games that have high quality sound, but they are few since it does not pay to increase the size of the game for a small portion of players.

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What is SPDIF & Optical? (SPDIF vs Optical): Comparison

by Sdh

S/PDIF vs Optical: What is the difference between SPDIF and optical? S/PDIF and Optical ports are available on many home entertainment devices, including Blu-ray players, set-top boxes, game consoles, PCs, etc. You can use these ports to connect a source device to a receiver, amplifier, speaker system, or soundbar. Both standards are capable of carrying digital audio signals.

However, it seems like many get confused between S/PDIF and Optical often. Odds are you’ve seen these ports behind your TV or other media device, now wondering what they are and how they’re different. This “SPDIF vs Optical” comparison guide will answer your questions and clear your doubts regarding the audio interfaces.

Table of Contents


What are S/PDIF and Optical?

Let this be clear: it’s possible to plug in both optical and coaxial cables in a S/PDIF jack, but the optical port only accepts optical (TOSLINK) cables. If you have an optical cable, you can use any of the interfaces to connect your TV to a speaker system.

Furthermore, both interfaces are digital, even though the coaxial cables for S/PDIF use the same type of connector found on analog RCA cables. However, don’t mix the digital coaxial and analog RCA cables as they’re different.

What is S/PDIF?

S/PDIF is an acronym for the Sony/Philips Digital Interface and the Sony/Philips Digital Interconnect Format. As the name suggests, Sony and Philips designed and developed this interface way back in the ‘90s.

Since S/PDIF is a data link layer protocol, it can transmit signals over either fiber optic cables with TOSLINK connectors or coaxial cables with RCA connectors. The particular format remains an interconnectivity medium for audio in today’s home entertainment systems and other Hi-Fi components.

Based on the AES3 standard, S/PDIF can carry two uncompressed PCM audio channels or compressed 5.1/7.1 surround sound. However, its inability to transmit lossless surround sound formats is notable due to the bandwidth limitations.

What is Optical?

Optical or TOSLINK (also known as Toshiba Link) is an audio interface that can convert digital audio signals to light beams and transmit them through a glass or plastic fiber optic medium. It utilizes the same software layer as S/PDIF, but it uses fiber optics over the electrical copper of coaxial cables.

With TOSLINK, the output electrical signals convert to red light beams that travel through the cable. The receiver on another end converts the optical signals to electric so that the input device can read them. Optical cables are also immune to external electromagnetic and radio frequency interference, unlike coaxial ones.

Optical can carry two channels of uncompressed PCM audio or compressed 5.1/7.1 surround sound formats, e.g., Dolby Digital, DTS Surround Sound. However, the bandwidth limitations make it incapable of carrying lossless Dolby TrueHD or DTS-HD Master Audio signals.

S/PDIF vs. Optical: Detailed Comparison

Followed so far what S/PDIF and Optical are? Now, we’ll walk you through the differences and similarities between them.

  • Judging by how they work, optical can be S/PDIF while S/PDIF can’t necessarily be optical. You can consider TOSLINK as a subset of the S/PDIF connector rather than a different signal transmission system.
  • Optical cables with TOSLINK connectors are generally shorter in length and more fragile than coaxial “S/PDIF” cables with RCA connectors. It’s because of the materials used in these cables.
  • The optical interface makes use of fiber-optic cables. Compared to the primitive coaxial cable generally used with S/PDIF, it reliably transmits signals and consumes less power. Plus, the use of light beams for data transmission makes optical insusceptible to EMI or RFI and signal loss over longer distances.
  • In contrast to the fragile glass or plastic fiber optics used in optical cables, coaxial S/PDIF copper cables are more durable. Granted, they aren’t as flexible or slim as TOSLINK cables, but they can survive bending, kinks, and pulls without permanent damage.
  • Optical TOSLINK cables use an odd-shaped, squarish connector, whereas coaxial cables use the RCA phono connector. The optical cable’s connector goes in one way, and the connection doesn’t nearly feel as secure as the coaxial cable’s RCA jack.
  • Both interfaces support a wide array of compressed audio formats regardless of the different connector types. However, they fall behind HDMI in terms of audio quality and bandwidth.
  • Neither optical nor S/PDIF (coaxial) can carry lossless or uncompressed surround sound audio formats.
  • Both S/PDIF and Optical are digital audio interfaces. The latter generally refers to the ADAT protocol over a fiber-optic TOSLINK cable, whereas S/PDIF makes use of a coaxial copper cable.
    Optical can carry up to 8 channels at 44.1/48 kHz or 4 channels at 88.2/96 kHz. S/PDIF can carry only two channels (stereo). Note that the optical interface can carry stereo S/PDIF signals too.
  • When it comes to connecting modern TVs with speaker systems, game consoles, AV receivers, and other media devices, the use of optical is more relevant. S/PDIF, on the other hand, is seen on older media devices like DVD players and HTPCs, ones that only accept coaxial cables with RCA connectors.

Also Read: Vizio TV Bluetooth: Pair with Headphones, Speakers & Soundbars

Pros and Cons of S/PDIF (Coaxial) and Optical

As you can see, the similarities and differences are less about S/PDIF and Optical and more about the cable and connector they use. Therefore, without going too much into detail, here are their main pros and cons:

S/PDIF (Coaxial)
Pros Cons
S/PDIF has a slightly higher theoretical bandwidth than Optical. The quality differences won’t be noticeable to most ears. It’s susceptible to EM and RF interference.
Sturdy metal connector; harder to unplug from inputs. S/PDIF can’t carry lossless audio formats.
Pros Cons
Optical offers more reliable signal transmission than coaxial. It has a slightly lower bandwidth, meaning slightly worse audio quality. However, the difference isn’t that noticeable anyway.
It’s immune to EM and RF waves. The connector is less sturdy and only goes in one way.

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S/PDIF vs Optical: Wrapping up

With that, this “SPDIF vs Optical” comparison guide comes to an end. Assuming you now have a clear idea about S/PDIF and Optical, the decision about what to use depends on what’s available to you. If it’s an option, we’d also recommend going with HDMI for connecting AV devices.

Once again, S/PDIF refers to a data format, where the data transmission can take place over various types of cables and connectors. Optical or TOSLINK is a physical medium, through which the signals go from one end to the other. It doesn’t even necessarily mention the connector type.

For the sake of the comparison, we’ve often associated S/PDIF with coaxial cables here, as the “S/PDIF” connector on most media devices accepts only the coaxial RCA cables.

Similarly, the “Optical” connector supports only TOSLINK cables, but it doesn’t tell us whether it uses the S/PDIF or ADAT protocol. That’s something you should look for in your device’s user manual.


Optical S/PDIF for PC / Habr

Digital interfaces have long been crowding out their analog ancestors. Mid-range audio systems use sound encoded in one of the many standards as a signal source. It can be the banal PCM for stereo sound or the Dolby family of standards for their multi-channel relatives. But today we will not talk about encoding methods, but about how exactly the signal is transmitted. There are only two options — optical and coaxial cable. The optics guarantee complete electrical isolation, the coaxial cable is easy to connect.

For ten years almost every motherboard has been equipped with an optical digital S/PDIF output (aka TOSLINK). But if you look at the back panel, you can not always find it. What’s the catch? The manufacturer is unwilling to install another connector on the rear panel and increase the cost of the board by installing an optical module or a coaxial cable jack. If you open the documentation for the motherboard, you can find a typical set of four pins similar to a speaker jack.

On the same page there is a branded bar with coaxial and optical outputs. Sometimes there are still optical inputs, but the author of the article only read about this on the net. Finding the original bar can turn into a non-trivial task — the price at foreign auctions is about $ 10, excluding shipping. A quick search of the Russian-speaking forums only finds requests to buy it and advice to buy a sound card with the appropriate slot instead.

So, we will make the bar ourselves. Despite the potential ease of manufacture, nothing similar was found for an optical connection on the network. There is more information on coaxial connection — but we want optics. So let’s start reading the documentation, for example here, S/PDIF Documentation.

According to the specification, the signal level on the motherboard is TTL, one can only guess about the load capacity of the SPDIFOUT output. The same documentation recommends loading it with an LED with a current-limiting resistor — this will be the cheapest connection. I did not dare to try this option first for two reasons — it was a pity for the board and the urgent need to stick a standard optical cable somewhere. Later, I nevertheless assembled an emitter follower on one transistor and connected an LED. The interface glowed cheerfully with a red LED, but the optical cable attached to it gave no sound. All the same documentation recommended picking up a super-bright LED with a wavelength of 660 nanometers. Perhaps none of the used LEDs fit.

The next step is to connect the recommended optical module TOTX173. The price and availability in online stores are again not encouraging — a little less than the same ten dollars and a long delivery. So it’s time to look for a donor. Having run through the home electronics dump, only one victim was identified, it turned out to be a Playstation 2, donated by employees for the last birthday. The hand on vandalism of the legendary prefix did not rise. At a regional online auction, a Samsung DVD Recorder was caught for the same sacred $10 without delivery. Photos will follow.

S/PDIF on the victim looked like this

Since the search for the code on the case (T2002H7) did not give anything, the device had to be turned on in the disassembled state in order to make sure that it was using five volts and a TTL signal level.

There are only three contacts, the common one is easily determined, the power is connected directly to the signed 5V plug, the information output remains connected through a 220 Ohm resistor. Here’s a close-up of our newfound module.

It remains to connect to the motherboard and assemble it all in the form of a bar. We connect the common output to the common one, power to power, and SPDIFOUT through a 220 Ohm resistor to data. We assemble a bar for a PC from a piece of a breadboard and a burnt out network card, I did it like this.

Installed in the housing.

More than two weeks have passed since the assembly — everything works fine. By ear, of course, the difference is within the limits of sensations given by psychology. But if there is acoustics that understands optics, why not use a do-it-yourself connection. In the comments, it would be interesting to hear an opinion about the possible difference in the sound of such an optical output and that obtained from a mid-range sound card.

After assembling, I got to the nearest home appliance repair shop. It was there that one should immediately look for a donor — they have a sufficient number of burnt DVD players, about a dollar for a fee. For those who want to repeat the design — it will be useful.

How to use the optical port (S/PDIF) in Windows 10


The optical output port on a PC remains a mystery to many people. Where it was placed in the back of your computer, it emits a constant red laser glow, whether or not anything is attached to it. It looks like you want to connect something to it, but what? The answer is logical: an optical audio cable, and here we will show you how to make it work, with the caveat that it becomes very difficult to use. Windows 10 operating system is correct in recent years.

How to enable optical (S / PDIF) sound on PC

First of all, there is an obvious problem — make sure that both your speakers and your computer have an optical (S / PDIF) port. If it’s not listed, just connect your computer to the speakers with an optical cable.

As with any other cable format, companies will try to claim that their cable is better than others due to gold plating, «high quality» or other marketing jargon, but ignore it all. Buying a cheap optical cable should be ideal, unless you plan to tie it in knots. Optical cables work similarly to HDMI in transmitting digital signals with virtually no degradation in quality. The main difference is that audio data uses less bandwidth than HDMI, so even if the cable quality isn’t great, it’s unlikely to be affected.

After connecting the optical cable, click the speaker icon in the lower right corner of the Windows taskbar, then click the speaker name above the audio slider to see if «optical» or «digital» audio output is displayed. If it is present, just click to enable it.

If the speaker does not appear there, right-click the speaker icon in the taskbar, select Sounds, and then the Playback tab.

Right-click anywhere on the Run tab and select Show Disabled Devices.

At this point, a device called something like «digital output» or «optical output» should appear. Right-click it and click «Enable» to enable it. After that, right-click it again and select «Set as default device». You should now have visual audio enabled.

How to Enable 5.1 Optical Surround Sound on Your PC

The real benefits of an optical cable become apparent when you plan to use surround sound, but there are quite a few criteria your computer must meet. Also, as a general rule, if your receiver/speaker has an HDMI port, you should use that instead as it provides better 5. 1 compatibility with Windows 10 drivers.0005

First of all, is the motherboard capable of outputting 5.1 surround sound? Having an optical output port does not guarantee that you will get surround sound in all games, movies, etc. The optical port on your motherboard should support 5.1 audio, although this will vary widely depending on which version of Windows you are using, whether it is recording it’s like a Dolby-compatible output, etc.

You can check if your installation supports Dolby 5.1 by going to the Sound -> Playback window. Right-click the device, select Properties, then the Advanced tab. Just click the drop down menu, select «DTS Interactive» or whatever 5.1 surround sound setting you want to use, then click OK. (If your computer does not detect Dolby Digital, you may need to work and we have provided links to some solutions in the feed.)

You must also click the Supported Formats tab to ensure that you select a format that the recipient can handle.