fiber optic cables!

Well, it's all optical so it's about optical properties...there's a dutch manufacturer that's using convex lenses on the cable ends to provide a more focused signal, and some others use glass instead of plastic because it provides a much higher MTF/OFT sharpness and far less constringence. That's the same kind of glass fiber that can transport data over thousands kilometers.

I've compared glass toslink to POF, it's a knock-out! Many other ppl claim to have heard the same difference....plastic is horrid sharpness-wise, and it smears the signal...which ends up distorting the signal and making the S/PDIF receiver clock recovery less effective.

But toslink is horrid jitter-wise, a properly galvanically isolated short 75Ω coax provides a much better SQ IME.

I could never tell the difference between glass or plastic, even when I unplugged the cable and shone it in.  I was using a nos dac though so everything sounded like ****

My opinion based in what I think is logic:
     Optical digital, as it's name implies is a digital interface. As long as the ones and zeros get through to the other side of the cable, there isn't a difference in quality at all, because all the signal is, is data (as opposed to a complex, analog signal that has a plethora of properties and "values" whereas data only has full throttle and none, 1 and 0). With a really bad cable you might lose some bits but then it's most likely not working at all because the data isn't getting properly through, and with a badly insulated optical cable there might be some sort of a buzz or interference from bright light sources like the sun (this interference speak is hearsay from a friend of mine who went the optical route way back so I can't vouch on it). Likewise, a music file or a digital photograph won't degrade in quality if you send them to a external HDD through a "cheap" USB wire, and a HDMI signal won't look better coming through a silver cable. If it does, I'd want to hear how does the cheap cable alter, drop and re-organize the ones and zeros to result into a different looking image or sound.

Quote:

Originally Posted by pocketrocket 

My opinion based in what I think is logic:
     Optical digital, as it's name implies is a digital interface. As long as the ones and zeros get through to the other side of the cable, there isn't a difference in quality at all, because all the signal is, is data (as opposed to a complex, analog signal that has a plethora of properties and "values" whereas data only has full throttle and none, 1 and 0). With a really bad cable you might lose some bits but then it's most likely not working at all because the data isn't getting properly through, and with a badly insulated optical cable there might be some sort of a buzz or interference from bright light sources like the sun (this interference speak is hearsay from a friend of mine who went the optical route way back so I can't vouch on it). Likewise, a music file or a digital photograph won't degrade in quality if you send them to a external HDD through a "cheap" USB wire, and a HDMI signal won't look better coming through a silver cable. If it does, I'd want to hear how does the cheap cable alter, drop and re-organize the ones and zeros to result into a different looking image or sound.

Unfortunately, you cannot compare SPDIF with other digital methods of transmission. When you copy files to and from your USB hard disk, the protocol is a two-way protocol and includes buffering and error-correction, which guarantees the data always ends up 100% correct at the other end.

The SPDIF specification, on the other hand, is a fire-and-forget method of transmission and it encodes both digital signal AND clock in the same transmission. Therefore the receiving end (i.e. the DAC) has no way of ensuring that the data is received (i) correctly, and (ii) on time.

Of course, toslink is reliable enough that we can safely assume (i) will never be a problem, so the other remaining issue is (ii) -- i.e. timing. Timing errors are expressed as jitter, and this is what causes the differences in sound.

Unfortunately I am not well-versed in jitter so if you want to learn more I'd suggest Google or any of the more learned members of the forum (or elsewhere, e.g. at computeraudiophile.com).

Ah, that's interesting! I'll certainly do some research on the topic then. Sorry for making assumptions about S/PDIF I didn't understand.

I suppose using as short cable as possible makes it easier to receive good signal? I never really noticed any significant defects in the sound when me and my father compared optical digital and RCA inputs on the receiver. Most significant difference was the greatly reduced noise floor as one might assume, and a tad more vivid transience (might have been noticed because of less noise too)