do digital outs differ one from the other ?

[Sean H]

Hi Jon- Do you find USB to be superior to S/PDIF (coaxial or Toslink)? As much as I love my dAck! 2.0 (Revolution soundcard coaxial output from PC) I have a modified M-Audio Sonica (Black Gates everywhere) and I almost share equal play between them both. The Sonica/USB (again heavily modded mind you) just sounds more relaxed and less forced, very musical.

 

[Jon L]

Quote:

Originally Posted by Sean H Hi Jon- Do you find USB to be superior to S/PDIF (coaxial or Toslink)? As much as I love my dAck! 2.0 (Revolution soundcard coaxial output from PC) I have a modified M-Audio Sonica (Black Gates everywhere) and I almost share equal play between them both. The Sonica/USB (again heavily modded mind you) just sounds more relaxed and less forced, very musical.

The problem we run into is that practically nobody is making USB solution that is "correct," which would involve asynchronous data transfer via USB cable, then the USB chip would hand off to the DAC chip via something like I2S connection, skipping the usual spdif connection. It would be best to "slave" everything to DAC's own super-low jitter clock.

I'm not aware of any company doing this at the moment. Wavelength might be doing USB better than most, but I can't be sure.

I use a modded Transit (Empirical Audio) using a purpose-tuned coax spdif out, and even though this is still not optimal, I would say the USB solution tends to sound less digital, more natural, less sibilant, with better flow and ease. But I can imagine somebody preferring a really well-done normal transport/spdif if you prefer a more forward, aggressive, obviously sparkly/airy sound if you are willing to tolerate more digititus and sibilance from lesser recordings.

The analogue output of my modded Transit (blackgates) sounds very good on its own also.

 

[thomaspf]

There is no fundamental difference to USB, S/PDIF, or for that matter 1394 if the master clock for the playback resides in the PC.

The fundamental difference between S/PDIF and USB/1394 is that S/PDIF is one-directional only while for both USB and 1394 there are standards that allow pacing the playback to a master clock in the DAC.

Unfortunately this potential benefit is mostly theoretical today since there are no implementations of these asynchronous modes (except for the audigy 2NX which comes with a different set of issues)

On the other side it is pretty straight forward to buy a DAC with either a digital output or a master clock output and find a sound card with S/PDIF outputs that can be slaved to an external clock. In fact most sound cards with digital input can be slaved to that clock.

Cheers

Thomas

 

[Kurt]

Quote:

Originally Posted by boodi aaaaaaaaaaahhhhhhh what i wanted ( didn't want really ) to know!!!!!!!!!!!!!!!!!!!!! this is bad new.

Why? A 0404 is cheap.
Click on “transports” on the following site. At the end of the descriptions you can see the retail prices for them.
http://www.highend-broker.com/index1.htm


Quote:

Originally Posted by Twombly To Kurt: Those tests were done sighted, no?

User reports are what I was talking about. If 9 out of 10 people say it is better, and even in which way and independent from another, the placebo effect pretty much goes down the drain and the message is more or less believable.


Quote:

Originally Posted by Twombly Shouldn't reclocking DACs reclock(duh) any digital signal to their own crystal's frequency anyway, negating the effect of any jitter upwards in the playback chain?

Yes, they should.
Actually, they seem to be little conmen, these DACs. Maybe we should inform the authorities.

SCNR

From http://www.geocities.com/jonrisch/jitter.htm

“Look into digital audio more thouroughly, and realize that
the implementations are not perfect or ideal, and are
sensitive to outside influences. Just because they could
have been and should have been done better or more nearly
perfect does not mean they were! People are not hearing
things, they are experiencing the result of products designed
to a cost point that perform the way they do in a real
world because of design limitations imposed by the consumer
market price conciousness all the mid-fi companies live and
die by.”


“Who cares what the power supply rails or the ground is doing?
The DAC cares, beacuse it is told to convert a digital signal
value at a certain time. This time is determined by the master
clocking oscillator in some designs, and in others by the
digital data stream itself by deriving a clock from the clock
data embedded in the data stream, and when the DAC
has determined that a transistion from logical one to a zero, or a logical zero to a
one, has in fact occured. The point at which the DAC decides
this has occured, depends on the absolute value of the power
supply rails near the moment of detection/conversion. The purity
of the master oscillator signal is also affected by PS and ground
variations, as well as sound vibrations, and the activity of the
various subsystems within the CD player/DAC box. If this master
oscillator signal is not perfectly pure, and free from noise, phase
jitter, and other artifacts, then even if the DAC was totally
unaffected by PS perturbations (virtually impossible to accomplish),
then the master oscillator signal itself would cause jitter.”

"It does seem that data buffers would eliminate any problem, but the whole thing arises because
the DAC can be affected by PS variations."

For me, the most probable explanation atm.

Cheers

 

[Zorander]

How about (any) differences between the digital out of popular cards like the EMU, M-Audio, etc? I am currently using the Revolution 7.1's digital out (I was using the Prodigy 7.1 previously) and I can't tell if any tiny differences I hear are real or just placebo.

 

[MoAv]

Damn , those are some serious acusation you've come up with ... and little old me thought that SPDIF/Optical/Coxial were perfect . jitter ? who needs it ? send it away .
Well I'd love to read more about it if anyone got some links .

 

[Twombly]

Quote:

Originally Posted by Kurt Why? A 0404 is cheap. Click on “transports” on the following site. At the end of the descriptions you can see the retail prices for them. http://www.highend-broker.com/index1.htm User reports are what I was talking about. If 9 out of 10 people say it is better, and even in which way and independent from another, the placebo effect pretty much goes down the drain and the message is more or less believable. Yes, they should. Actually, they seem to be little conmen, these DACs. Maybe we should inform the authorities. SCNR From http://www.geocities.com/jonrisch/jitter.htm “Look into digital audio more thouroughly, and realize that the implementations are not perfect or ideal, and are sensitive to outside influences. Just because they could have been and should have been done better or more nearly perfect does not mean they were! People are not hearing things, they are experiencing the result of products designed to a cost point that perform the way they do in a real world because of design limitations imposed by the consumer market price conciousness all the mid-fi companies live and die by.” “Who cares what the power supply rails or the ground is doing? The DAC cares, beacuse it is told to convert a digital signal value at a certain time. This time is determined by the master clocking oscillator in some designs, and in others by the digital data stream itself by deriving a clock from the clock data embedded in the data stream, and when the DAC has determined that a transistion from logical one to a zero, or a logical zero to a one, has in fact occured. The point at which the DAC decides this has occured, depends on the absolute value of the power supply rails near the moment of detection/conversion. The purity of the master oscillator signal is also affected by PS and ground variations, as well as sound vibrations, and the activity of the various subsystems within the CD player/DAC box. If this master oscillator signal is not perfectly pure, and free from noise, phase jitter, and other artifacts, then even if the DAC was totally unaffected by PS perturbations (virtually impossible to accomplish), then the master oscillator signal itself would cause jitter.” "It does seem that data buffers would eliminate any problem, but the whole thing arises because the DAC can be affected by PS variations." For me, the most probable explanation atm. Cheers

The Hirsch "paper" fails to provide statistical evidence of an audible difference under controlled (read: unsighted) conditions. Furthermore, there is no study cited in which " zOMG engineers on the cutting edge" posit that 10-20 picoseconds of jitter is enough to create an audible effect.

As for your 9/10 argument, it's bunk. You're assuming that placebo effect is negated with a 9/10 agreement to prove the non-existence of a placebo effect.

 

[thomaspf]

The 10-20 ps go back to the AES paper fron Dunn in which he calculates that above 12ps you migth get distortions on the same mangnitude as changing a bit in the stream.

Whether you can hear this is still a good question.

Cheers

Thomas

 

[Twombly]

Quote:

Originally Posted by thomaspf The 10-20 ps go back to the AES paper fron Dunn in which he calculates that above 12ps you migth get distortions on the same mangnitude as changing a bit in the stream. Whether you can hear this is still a good question. Cheers Thomas

Not only a good question, but the actual crux of the debate. The sources cited provide theoretical and measurable changes, but, as is the mantra on many a hi-fi forum, "measurements don't matter."

 

[thomaspf]

Well, in case this was not already clear. I am not subscribing to the camp that measurements and physics does not matter.

This leads to a dictatorship of irrelevance where all opinions are of equal value, that I personally don't find acceptable.

I also know that my ears have degraded quite a bit with progressing age.

Cheers

Thomas

 

[Kurt]

Quote:

Originally Posted by Twombly The Hirsch "paper" fails to provide statistical evidence of an audible difference under controlled (read: unsighted) conditions.

The Risch "paper" can not fail what it does not even try. It is about jitter and not about statistical evidence of audibility.


Quote:

Originally Posted by Twombly You're assuming that placebo effect is negated with a 9/10 agreement to prove the non-existence of a placebo effect.

Nice sentence.

This would be statistical evidence however.

As for the audibility debate:
It is in the nature of differentiating that it is about small or even very small differences.

My hearing ability varies because of expectations, daytime or other every day influences. These variations are big enough to either make small differences inaudible or exaggerate them.

This is one of the reasons why I am not interested in small differences.
And consequently do not talk or post about them.

Cheers

 

[K2Grey]

IIRC placebo effect can happen with majority very easily. But I think anyone who wants to talk about the placebo effect should do research on it instead of just guessing at what it was.

For example, I used to see posts on head-fi by some doctor who noted that in double blind drug studies, many people who had already taken drugs for their illnesses without effect, and thus were skeptical about the new drug, got better after taking it. But it was sugar pill - so the placebo effect worked on them even though they didn't believe the drug would work. This seems to contradict people's uneducated guesses at how the placebo effect works, so I think a bit of research is required on this subject, lest people say things like "I invited a few objectivists over to try my power cords, and they thought there was a difference, so that proves it's not placebo" and be misleading.

Of course, I myself am uneducated in the placebo effect and how it works and famous studies concerning it and so on, but I'm just cautioning that laymen should probably not post their guesses about it on a forum where people will take those words as indicating actual knowledge.

 

[Zorander]

Having replaced the Prodigy 7.1 with the Revo 7.1 (both using digital outs), I can confirm that the latter seems to produce more dissipated sound and with a slightly brighter balance. Maybe it's due to the fact that I am using a 5m-long coax cable (and the Prodigy coax output is more tolerant of the increased cable resistance than the Revo's). Or do Digital outs really differ from card to card?

 

[Twombly]

"Statistical evidence" under non-controlled conditions =/= evidence of anything. There are other significant variables that could plausibly affect the outcome.

As for my comments on the Risch paper, fine, I'll rephrase them. The Risch(sorry) paper fails to provide any evidence whatsoever of an audible difference - merely theoretical reasons for a measurable difference.