[tourmaline]

For digital cables , quality isn't as important as for analogue cables. They are more prone to interference then digital cables. Any fair priced cable will get you a good sound. There is a difference when you go up the ladder, but not as noticable as with analogue cables. As said earlier, if you have enough quality there, you're set. All you wanna avoid with digital cables is that the error correction kicks in, that is audible! Jitter etc, has probably more influence on the sound.

 

[Chri5peed]

Just ordered the Optocoupler. Damn you head-fi!

 

[krmathis]

Quote:

Originally Posted by Chri5peed /img/forum/go_quote.gif Just ordered the Optocoupler. Damn you head-fi!

Great choice!
I am sure you will be pleased with it...

 

[Chri5peed]

Quote:

Originally Posted by krmathis /img/forum/go_quote.gif Great choice! I am sure you will be pleased with it...

I should change it to 'damn you Krmathis'

I asked for a link to buy the $45 Monster iCable, instead I get the $120 Optocoupler!

 

[krmathis]

^ LOL

 

[Xenafor]

Sorry, bit of a noob question, but you would never plug an optical cable into a non-DAC amp, would you? When, then, does one use an optical connect?

 

[infinitesymphony]

Quote:

Originally Posted by Xenafor /img/forum/go_quote.gif Sorry, bit of a noob question, but you would never plug an optical cable into a non-DAC amp, would you? When, then, does one use an optical connect?

Between the transport and the DAC, for example from a CD player's TOSlink output to a DAC's TOSlink input. Amplifiers only accept analog input, except for DAC/amp headphone combos and home theater receivers / preamplifiers, which tend to have built-in DACs.

 

[Kaluminati]

I think conclusion should be that, if you bought an expensive optical cable already, then indeed it does make a big difference. If not, then no there would be no difference in sound quality if you bought a $200 toslink to replace your $30 one.

;P

my 2 sense (yes, sense)

 

[krmathis]

Quote:

Originally Posted by Xenafor /img/forum/go_quote.gif Sorry, bit of a noob question, but you would never plug an optical cable into a non-DAC amp, would you? When, then, does one use an optical connect?

Correct!
Its used between the transport (ex. CD transport or computer) and the external DAC.

 

[Pibborando]

Quote:

Originally Posted by Xenafor /img/forum/go_quote.gif Sorry, bit of a noob question, but you would never plug an optical cable into a non-DAC amp, would you? When, then, does one use an optical connect?

If you can find a place to plug an optical cable into an amp with no optical in... then you might have more problems than you realize.

 

[GANESHA]

Quote:

Originally Posted by c0mfortably_numb /img/forum/go_quote.gif I noticed a night and day difference between a cheap oem Toslink I got on eBay, and the premium 8.0mm Toslink from Monoprice. The Monopriceis also bargain priced at $6.42

Which one was better?

 

[infinitesymphony]

Quote:

Originally Posted by GANESHA /img/forum/go_quote.gif Which one was better?

Judging by his wording, I think he meant to imply that the Monoprice cable was better.

 

[Pars]

Quote:

Originally Posted by Chu /img/forum/go_quote.gif The thing about digital is that past a certain threshold, it just doesn't matter anymore. Once you're bit-perfect you are good. <snip>

The only problem with this is this isn't really digital... it is a digital signal transported across an RF medium (i.e., analog

), irregardless of whether it is optical or coax (electrical).

Yes, there is correction for the data (AFAIK). What about the biggest problem with SPDIF... the clock? This is multiplexed onto the bitstream and is supposed to be extracted at the end. There isn't any error correction on the clock signal.

Bit-perfect simply means the bit pattern of the data at the end matches the transmitted data. In other words, all the music data arrived at the DAC.

The other part of the puzzle is to make sure that it arrives at the DAC and is clocked into the DAC chip at the right time (jitter), which involves recovering the clock in real-time, and is where things go awry in SPDIF (or TOSLINK). Even if you fix all the impedence mismatches (reflections), etc., the format itself is compromised... which is why you see some recommend that the DAC contains the master clock, and the clock is slaved (via I2S or whatever) back to the transport.

 

[Chu]

Quote:

Originally Posted by Pars /img/forum/go_quote.gif Bit-perfect simply means the bit pattern of the data at the end matches the transmitted data. In other words, all the music data arrived at the DAC.

No, it doesn't.

When I say bit perfect I'm referring not only to the actual sequence of bits, but also reproduction within certain temporal thresholds. This is the generally accepted definition, because if a certain temporal specifications is not met, at some point either you're going to overflow your buffer or discard late packets, which means your stream is no longer bit perfect.

These specifications are very well defined, and even coat hangers have proven to be good enough to meet it in lab tests with copper digital cables. I'm having trouble thinking of an equivalent for optical, but I'm sure I could find something interesting with some work.

Also, note that the manchester-esque encodings being used are self clocked. You seem to be describing a system where there is a "clock signal" and an "audio system" where if the two get skewed (i.e. jitter) things start going wrong. This is not true, the data itself is the clock.

 

[Pars]

Quote:

Originally Posted by Chu /img/forum/go_quote.gif No, it doesn't. When I say bit perfect I'm referring not only to the actual sequence of bits, but also reproduction within certain temporal thresholds. This is the generally accepted definition, because if a certain temporal specifications is not met, at some point either you're going to overflow your buffer or discard late packets, which means your stream is no longer bit perfect.

The definition I see on sites such as audioasylum, etc. seems to be more along the lines of what I described.

Quote:

Originally Posted by Chu These specifications are very well defined, and even coat hangers have proven to be good enough to meet it in lab tests with copper digital cables. I'm having trouble thinking of an equivalent for optical, but I'm sure I could find something interesting with some work. Also, note that the manchester-esque encodings being used are self clocked. You seem to be describing a system where there is a "clock signal" and an "audio system" where if the two get skewed (i.e. jitter) things start going wrong. This is not true, the data itself is the clock.

Yes, I probably did not describe it well. The clock (wordclock) is actually used to mux the data, and it is this timing that is hopefully recovered by the receiver, thru PLLs, etc. One would note that many of the more popular hi-end DACs spend alot of effort in reclocking the incoming SPDIF signal to attempt to eliminate the inherent clock jitter (Benchmark DAC1, Lavry DA10 to name a couple). Professional solutions slave the transport to the DAC clock via a separate link. A couple of links to note:

http://www.audiocraftersguild.com/Aa...on.jitter2.htm

and

http://audio.peufeu.com/node/7

including the linked AES paper by Dunn and Hawksford.