James did indeed reply, and seems like a very nice gentleman.
I'm not sure how to evaluate the reply - he seems to agree with my assessment of Redbook audio, then talks about phase shift in amplifiers, how the DAP acts on ultrasonics, and states that CD players have output above 30khz irregardless of engineering principles.
I guess it becomes a matter of faith (and in this hobby I've heard "impossible" differences in components before).
Looking forward to a review from an actual user.
My original email and reply below.
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Hi Mark
Thanks for the enquiry. As you are very aware the basic operating principles of 16bit digital are as you have stated.
The factors of reproduction above 22Khz for do not cover the full output stage plus analog filtering.
If you send a 10Khz signal into an amplifier you dont just get 10Khz out!
The DAP.10 does not process in the audible domain but this does not mean that it has no effect on it.
As you also know theory and practise are two very different things. The theory behind 16bit, 24bit, SACD bares nothing to sound reproduction.
Its the first thing you need to remember in R&D
..dont read the book!
If that were the case a Mark Levinson CD player would sound the same a $500 Marantz CD player.
Ever heard a discrete super tweeter? Why does it work?
There is more to digital sound reproduction than what is written in the RED book as many highend audio manufactures already know.
What we found about 4 or so years ago was that well above 30Khz all CD players exhibit several extremely low level peaks.
What causes these peaks are still in R&D. We also found a fair amount of out of phase information in the same areas.
Out of phase information is quite typical in any audio amplifier, whether it be in a buffer stage or output stage.
What we also noticed was that by applying a phase shift to one of the peaks, caused a fairly unpleasant ripple to be sent back down
the audio band. Applying a similar shift to another reduced its effect. After much peak-selection and phase shift circuits we managed to
reduce the amount of ripple being sent back down the audible band with out actually touching it. Youll find that with a DAP.10 in a system
the inherent system sound (signature) does not change but the system resolution does.
I hope this answers your question. The thing to do is to listen to one.
What system do you run? Are you relatively happy with it?
best regards
James
-----Original Message-----
Sent: 29 December 2004 04:16
To: post@whestaudio.co.uk
Subject: Question about DAP 1
Can you shed some light on the operation of your DAP 1 processor? I've been considering ordering one, but am unclear on its operating principles.
Your site claims that the DAP acts to realign frequencies above 35khz and has no effect on frequencies below this point. The problem I have is that no properly designed CD player, whether oversampled, upsampled, or non-oversampled (1FS) has any output above 22.05 khz (half the Nyquist sampling frequency of 44.1 khz). One of the major jobs of the reconstruction filters (digital and analog) in the player/DAC is to block everything above this point.
SACD has output beyond 35khz, but much of this is quantization noise relocated from the audio range to this region by the player's noise shaping circuits. It has little correlation to the music.
If your processor has no effect on signals under 35 khz, then how can it have any effect on the sound of the CD player?
Regards,
Mark Guidry
