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Technical and scientific discussion of amps, cables and other topics.

RE: "It won't hold up."

The question of whether CD players have an identifiable sound is irrelevant to the research written up in the paper, which is an attempt to answer a specific question. Here’s a restatement of our question, one more time: High-bit recordings have a reputation for sounding very good, and some listeners say this is because of their higher bit rate. If this is true, then when we convert high-bit audio to 16/44.1 and back to analog, we should hear degradation in the sound. Is this effect audible?

There is nothing about CD players there. The A/D/A conversion was done using an HHB model CDR-850 professional CD recorder. If you press the REC button, the HHB goes into record monitor mode and lets you listen to its converters. The digital bit stream appears at the coaxial, optical and AES/EBU digital outputs and the analog output of the D/A converter appears at the line outputs.

The fact that the HHB can also record its digital bits on a CD did lead to certain opinions, expressed in the paper’s addendum, relating to CDs. If you use the CDR-850 to record the bits on a CD and then play it back, the result will sound the same as we heard at the analog output. Research from the early 1980s (some of it done by David Ranada and reported to me personally) supports this assertion, indicating that even inexpensive, mass-produced CD transports do, without requiring super-clean discs, deliver the original bit stream to the converter with no errors or jitter problems.

You might not accept that premise, but to anyone who does, the opinion expressed in the paper -- that all but one of the recordings we heard could have been released on a CD with no audible difference – makes sense. That’s a “logical sonic connection” with CD sound, though it’s not the main subject of the paper.

This is the part that you never seem to acknowledge, so I can’t tell whether or not you even get it: If the D/A converter and/or the analog circuit in the HHB have, as you claim they must, an identifiable sound of their own, our listeners would have been able to tell that sound from the original. They couldn’t. If you think you can identify this or any other characteristic of our B chain, you’re welcome to try. We are hoping to go back to the new custom-built listening room of our audiophile host in a few months, when it is completed and his system installed, to do some more tests for the threshold of detectability of the CD noise floor. You can come and do the test there if you like. (I can guarantee at least some positive results for everyone.) I won’t hold my breath, though.

The aforementioned system includes wide-range electrostatic speakers and presumably meets whatever criteria you have chosen to impose on this process. But you also accuse our main system of being, in your coined term, a “phase incoherencer” capable of hiding acoustical cues. There is no reason to believe it is any such thing or can do any such thing. To anyone interested in studying the available data on the audibility of phase shift (which in subjective audio circles is often, as here, vastly overstated) I recommend you go to www.aes.org and search the literature for Douglas Preis (listed most often as D. Preis). There are basic tutorials as well as papers on specific issues such as digital anti-aliasing filters.

As for the offense you purport to take at my tone, my remark about your superior intelligence was not meant to be ironic or insincere at all. As for the rest, I admit it is difficult to discuss these issues with you and sometimes I get a bit testy. You misunderstand and/or distort what the experiment is about, you have been unremittingly contemptuous and sarcastic in your tone, and you have coyly implied that Moran and I are concealing our real purpose, whatever that is supposed to be. I have been far more civil to you here than you have to me, as a quick comparison of your posts and mine will verify. So I would respectfully suggest that if you can’t take it, don’t dish it out; be civil to me, lose the mockery, and I'll reciprocate. – E Brad




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  • RE: "It won't hold up." - EBradMeyer 10/23/0712:00:32 10/23/07 (0)

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