Albert wrote on Wed, 03 November 2004 17:20 |
Okay, I hate to interrupt this heady and intense discussion with the ridiculous, but I have a simplistic nuts and bolts type question.
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It's not ridiculous, Albert, you're cool! We need lots of practical questions and examples to help illustrate the theory versus the practical.
In order to answer your question, let me ask: did you catch the part of this thread where Dan Lavry suggests making a chain with a series of T-Connectors, to avoid the jitter which can be added in a distribution amplifier?
How many actual CONVERTERS and channels do you want to sync up? Which models are they and what are their syncing possibilities?
If any of the things that you want to sync up ARE NOT CONVERTERS, then you can just use plain ol' AES/EBU sync or a WC distribution amplifier to feed those. Tell us more and maybe we can come up with a plan that answers your question!
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Back to the "Big Ben" discussion, maybe we should split the thread...
On listening tests for jitter. We have to separate the hype from the facts. It is EXTREMELY difficult to do an A/B comparison between clocks by the way, scientifically and blindly. The reason is that EVERY clock circuit takes time to stabilize; and many converters mute during the stabilization period or switch period. This very gap in sound (can be as long a 5-10 seconds or longer in some models) totally destroys the ear's memory for sound. If you have a preconceived notion of what effect an external clock will have on the sound, then it can be very difficult to prove whether we are not just "dreaming it all up". The ONLY fair listening test for D/A converters on external versus internal clocking would be to have two identical models of the same converter and be able to switch between them. Fair enough? Max is invited to supervise my tests, but I think he'll find that I am a very fair and open-minded listener. Even though I am biased against DSD, for example, I've found some surprising and puzzling sonic improvements with upsampling to DSD in blind tests.
My listening record demonstrates that several times in the past I have discovered and verified OPPOSITE conclusions to my own biases. In the case of the famous "filter tests" for example.
So I think that I can conduct fair and open listening tests, but Max is welcome to supervise, as I said.
For the DACs, he should bring TWO of each converter to the test. Any other listening test is bogus or suspect. How many of you out there have performed clock comparisons with identical converters? I admit it, I haven't! So all my tests are suspect, at least on the D/A side.
Clock listening comparisons can be done on the A/D side with a single converter since the results are recorded into a file. And the two files then can be auditioned into a single D/A.
We shall see, if Apogee sends me a Big Ben and two converters. My assistant's ex college roommate is now working for Apogee. I don't know Max personally and I feel very bad for being so confrontational. But this is science, and he's been responding on the "feeling good" level with no measurements to support the voodoo. No measurements I've seen, at least. How many objective listening tests? How many measurements of the jitter?
The other poster who claimed that his TC 6000 improved with Big Ben. I had the opposite experience; the System 6000 was MARGINALLY superior on internal clock, exactly as its measurements imply. But I did not apply the Big Ben. I used another stable clock; I'm willing to listen (and measure) again with the Big Ben, voodoo not withstanding. Ironically, I'm no longer using the System 6000 converters... I've "moved up".
I am trying to remain on the scientific level in this thread, despite that I am a very critical listener by profession and by instinct. On the scientific and technical level, my points, Dan's, and several others' are very hard to refute. Dan is even aware of the technology behind the Big Ben; depending on the nature of the jitter which this technology produces, in combination with the PLL of the receiving circuit, it could produce jitter at the converter which could produce a "vaguer image" rather than a "wider, stable image". This can fool a lot of ears...it can easily be a case where "more jitter" sounds better than less.
So we have to learn how to be objective in our jitter listening tests as well! Think of it like coincident pair miking versus spaced miking. Is "more pleasant to the ear" more correct? So to really know whether the converter is lying or telling the truth, we need an analog source to compare it to. Or, at the least, we have to know a lot about the miking which was used in the recording which we are evaluating; if a coincident pair starts to sound like a spaced pair with the Big Ben, then I would call it "jitter-induced hypnosis"
. The space has to increase while the apparent stability and size of the center image has to remain rock steady, in order to qualify for a genuine sonic improvement.
Regarding user "bias"---it is true... Dan has product to sell, but so does Max, and we must recognize that money drives the world, even though I think Dan has done an excellent job nearly completely separating the theory from the "brand practice". If Max is not going to provide the measurements or the theory, then he has to post more than just listener endorsements by name. He has to post some written critiques, fine descriptions of the sonic effects, and descriptions of the objective nature of the test methods so we can effectively criticise and evaluate the results.