Questions About S/PDIF

I am glad that a digital audio interface now exists to eventually replace the old analog audio interfaces that are still ubiquitous in electric equipment today, and I hope to eventually own a speaker set that uses this new S/PDIF standard, but I have several questions to ask about it before I make such a purchase and investment.

First, why does the S/PDIF standard use only a single pin in its connector, and why is that pin exposed? Most other interfaces standards have multiple pins for transmitting large amounts of data simultaneously, and those pins are embedded into the connector to prevent them from being damaged (such as USB and HDMI connectors). With only a single pin, it seems to me that an S/PDIF connection is limited in the amount of data that it can transmit at one time, and with that pin being exposed, it is vulnerable to being damaged. Additionally, the connector too strongly resembles an old analog connector, which could lead to confusion and simply is odd to me, as newer connectors usually are very different in appearance compared to the old connectors that they replace, such as a SATA conenctor in comparison to a IDE/PATA connector. Would it not be better to have a digital audio connection that had multiple pins for better data transmission, those pins embedded to protect them from damage, and a different appearance from analog connectors to distinguish it?

Second, does S/PDIF offer plug-and-play capability, as do USB and HDMI, and can it convey information between the computer and audio devices (such as model name or number of sound channels), the way that Display Data Channel does for monitors?

Third, how long may it take for digital audio connections, S/PDIF or otherwise, to completely replace analog connections and become as ubiquitous as are analog connections, currently? I notice that S/PDIF connections currently are used only in expensive, high-end audio equipment, and I am hoping that they shall eventually be used in all audio devices, which nearly all use a 3.5 mm TRS connection.

What does everyone else have to say on this subject? What insight can you offer? I await your responses.

S/PDIF is nothing new. It's available as the coax connection your referring to and optical.

The PlayStation 2 had an optical output on it. I can't seem to find when exactly S/PDIF was released, but the PS2 came out in 2000.

Have a read about S/PDIF.

1) You'd have to really try to bend that coax pin. I don't think you could ever do it accidentally. To be honest, audio is a lot less complex than video and doesn't require nearly as much bandwidth. The optical version (which I happen to use) is overkill for surround sound. Coax cables are coax cables. It looks the same as an analog cable because it pretty much is the same. It just has different dimensions.

2) It is plug and play as long as the connected devices are setup to use spdif. It transmits 1-way audio data only, so no hardware data or 2-way communication.

3) In the audio world, analog is considered better than digital for the most part. Analog is a pure waveform whereas digital can be closely simulated but can never be perfect. The sound quality from a vinyl record > an mp3 or even lossless FLAC files. I don't know that analog will ever be replaced completely with digital simulation in this realm. Truly high-end audio gear still has vacuum tubes!

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Originally Posted by Collinstheclown

S/PDIF is nothing new. It's available as the coax connection your referring to and optical.

The PlayStation 2 had an optical output on it. I can't seem to find when exactly S/PDIF was released, but the PS2 came out in 2000.

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I know now that the interface is not new, but I learned about it for the first time only very recently, so I did not know until I researched it that it was not a new connection.

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Originally Posted by Airbozo

Have a read about S/PDIF.

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I have read that article, and while it is informative, it does not provide the information that I seek; if it did, I would not needed to have started this thread.

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Originally Posted by mDust

1) You'd have to really try to bend that coax pin. I don't think you could ever do it accidentally. To be honest, audio is a lot less complex than video and doesn't require nearly as much bandwidth. The optical version (which I happen to use) is overkill for surround sound. Coax cables are coax cables. It looks the same as an analog cable because it pretty much is the same. It just has different dimensions.

2) It is plug and play as long as the connected devices are setup to use spdif. It transmits 1-way audio data only, so no hardware data or 2-way communication.

3) In the audio world, analog is considered better than digital for the most part. Analog is a pure waveform whereas digital can be closely simulated but can never be perfect. The sound quality from a vinyl record > an mp3 or even lossless FLAC files. I don't know that analog will ever be replaced completely with digital simulation in this realm. Truly high-end audio gear still has vacuum tubes!

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These are the type of answers that I was seeking; thank you very much.

Your first two answers are acceptable, although I was under the impression that coaxial cables are becoming less popular in favor of other cables. For your third answer, I thought that digital signals were superior to analog, as most computer interfaces, notably video interfaces, have transitioned from analog to digital. Plus, is digital not immune to the possibility of distortion, such as the crackling or hissing that plagues analog signals?

Devices that only have one S/PDIF port seem to usually have only the optical (TOSLINK) connection, so you may be right that manufacturers are moving away from coax. Using a fiber optic connection has its pros and cons, though the typically short distances between consumer S/PDIF devices alleviates a great deal of the cons. With the fiber optic there is no shortage of bandwith for data transmission.

That being said, mDust is correct. Analog is the preferred signal type in audio. While digital is better for video, audio waves are more accurately replicated with analog. If you think about the waveform for a given sound, its a smooth sine wave. Now try and replicate that smooth wave with a format that is on or off. What you get is a series of steps in the waveform. The faster the digital signal can be processed, the smaller each step can be and the waveform will be closer to the original, but it will still be a series of steps and your ear can pick up on the difference.

well, no matter what, the digital audio signal has to be turned into an analog signal sooner or later. whether it's done at the computer and then transferred to the speakers as an analog signal or it's transferred as a digital signal and then converted to analog at the speakers. either way, the speakers use a sine wave.

as for video, the digital signal used to be converted to analog due to crt monitors needing an analog input. now that we have digital flat screen monitors, it is an unnecessary step to convert the video to analog and then back to digital for the lcd display to show video. so the digital video signals have pushed out analog there.

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Originally Posted by DemonDragonJ

For your third answer, I thought that digital signals were superior to analog, as most computer interfaces, notably video interfaces, have transitioned from analog to digital. Plus, is digital not immune to the possibility of distortion, such as the crackling or hissing that plagues analog signals?

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Superior in what way? Both digital and analog have pros and cons.

Analog signals are a pure waveform, which is great for audio, but they are susceptible to interference from nearby electronics (noise) and poor connections (which cause hissing/crackling). Analog cables used in home theater environments are shielded to prevent interference and (if you spend the money) have high-quality connectors that prevent poor connections. Analog also can only be transmitted so far (depending on a lot of factors) and then has to run through a repeater which just listens to the signal and replays an identical signal down the next segment of cable.

Digital is a simulated waveform which is better suited to long distance runs, high electrical noise environments, and applications requiring large amounts of bandwidth (such as ethernet/TCP/IP and video signals). It generally offers higher bandwidth and smaller 'file sizes' due to compression algorithms that often sacrifice quality for quantity. Digital is almost entirely immune from electrical noise, suffers little due to poor connections that would cause cracking/popping/hissing, and can travel much further before requiring a repeater.

They each have many more pros and cons, but these are the basics. For audio, analog is preferred for quality reasons. The more money you spend on your home theater gear, the more thought has been put into minimizing cons and maximizing pros regardless of which technologies were incorporated...that or you spent a pretty penny on a shiny brand logo.;)

The reason that I started this thread is that I shall be using my computer for all my multimedia and entertainment purposes, including both music and movies, and I wish to have speakers that shall produce high-quality sound. Thus, I now ask: do I need to spend three-hundred dollars on this speaker system here, which has a digital input, or should I save money and instead purchase this speaker system, which has only an analog input, but costs only seventy dollars?

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Originally Posted by DemonDragonJ

The reason that I started this thread is that I shall be using my computer for all my multimedia and entertainment purposes, including both music and movies, and I wish to have speakers that shall produce high-quality sound. Thus, I now ask: do I need to spend three-hundred on this speaker system here, which has a digital input, or should I save money and instead purchase this speaker system, which has only an analog input, but costs only seventy dollars?

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You have to consider more than just IO connections...
The cheap one is 50W total power whereas the z906 is 500W. There are several other differences, but the gist of it is that the z906 is higher quality. You usually get what you pay for, but watch out for a marketing scheme called 'prestige pricing'.