Why do digital cables sound different?

"Yes" is the short answer. I don't necessarily agree, but that seems to be the point of view of this community.

I'm jumping into this late but here goes.

First, don't assume that people who can't hear the difference in digital cables have a bad system or bad ears. Maybe they are just fortunate that their system components match well enough that the cable isn't much of an issue. Having a system that is very sensitive to cable changes may not always be such a good thing.

Second, I've tested a few ADC's (similar to DAC's) and clock jitter is extremely important in reducing harmonic distortion at audio accuracy levels. As mentioned above, errors in the time position of the sine wave samples will distort the sine wave, just as voltage errors will.

What we're talking about is two issues: data recovery from a serial bit stream and also clock recovery from the same serial bit stream.

Although data bits errors should be rare in a well-designed and well-matched system, they will cause serious problems when they occur. As noted above, there is no error detection or recovery mechanism for data errors. All serial data transmission schemes will miss data occasionally and the measure of that is the "bit-error rate".

Clock recovery circuit design is almost an art. I'm not familiar with the CD standards. I assume that the DAC's clock recovery circuit uses a PLL. Is this correct? The PLL will filter out alot of the high frequency jitter. Better PLL designs will filter out more jitter.

We have equipment to measure jitter where I work. The accuracy is in tens of picosends. The inputs are all 50 ohm. This equpment should be usable for testing the transport/cable jitter. Does anyone have ideas for some easy experiments using this equipment? It might be interesting to measure several types of transports.

Leme@lone.com
No actually you'd be wrong!...I swear!!!
In one of John's (Dunlavy's)systems, HE WAS USING LAMP CORD FOR THE SPEAKER CABLES!!!!(all-be-it 12awg).
Now don't get me wrong, I think the gear he was using was not so good either. Infact the refernce system, which used SCIV's, had Marantz MA500 mono blocks, and a digital Marantz pre/pro up front!!...OH THE GLORY OF SOUND!!!! Patch cord IC's, Lamp cord for speaker wire, mid-fi(at best) gear...I couldn't believe what I was seeing/hearing!
He believed(JD) that a good amp was a good amp, and all wire was the same if it measure(with his test equipment) proper impedence/inductance/capacitance or whatever, it HAS TO SOUND THE SAME he stated! Infact, he went on to often say that "God himself couldn't hear the difference in two wires/cables measuring the same values!!!!! Ehem......

Does anyone know where i can find some THX certified
lamp cords?

Foreverhifi: I might agree with John Dunlavy regarding his comments "God himself couldn't hear the difference in two wires/cables measuring the same values!"

If the cables presented identical loads to the source component with the same level of signal transfer into the load component, they "should" sound identical. However, it would be possible to measure cables and have them come up the same yet be electrically VERY different from one another.

One could use a cable constructed like Kimber 8TC and insert inductors in each leg of the run and then take a run of 10 gauge zip cord and insert capacitors in each leg of the run. The total resistance, inductance, capacitance and impedance for both cables may measure the same on a meter but the fact that some components were lumped and others were evenly distributed would cause current to flow VERY differently along the length of the lines. As such, "tuned networks" within a small area may not be as effective as achieving similar electrical characteristics over a wider spread and vice-versa. Much of this will depend on what you are trying to achieve and the rest of the circumstances involved. Whether or not we can actually hear such things is a good question and one that i would love to be able to know ( and prove ).

As to the cables that Dunlavy was using, i would have thought that he would have been using some of his own speaker cables and interconnects. As to his choice of gain stages, he should have known better than to say that "an amp is an amp" etc... He used to design and market components back in the 1970's and they were very well thought out in terms of circuitry. I don't know how well they were constructed or if he paid attention to parts selection, but he knew enough to try and design something that was "technically correct" to say the least. He is a very smart guy but whether or not he applied everything that he knew at all times is another matter. Sean
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