Boa2 - email sent. I'll post the response if/when I get one.
Showing 8 responses by ghostrider45
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. *********************************************************** 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: [email protected] 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 |
Boa2 - Please let us know what you think of the unit when you get it. I'm on the fence about ordering one. First, it's silly expensive, and second, its operating principles don't make sense. Whest 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. SO what is this box really doing? Since my DAC has no output above 22.05 khz on Redbook, then what is this box acting on? Let us know your impressions. |
OK guys, I just qualified for my sucker certificate - Audio Advisor had two DAP 10R's up for auction on ebay. Both were customer returns and are supposed to fully functional (no burning smells, both channels working, etc). No return privilege, of course, but full factory warranty (whatever that means....) I won one today for 1099. The other didn't make reserve and is re-listed. I'll let you guys know what I think when I get it. |
Well, I got my DAP10 yesterday. I hooked it up and guess what - no right channel. I wonder if they sent me BOA2's unit! Since I'd asked Audio Advisor explicitly whether or not the unit was working before buying, and they answered "yes", they're going to get me a replacement unit. What I heard through the left channel alone was promising. I'll post again once I see a new unit. |
I tried the replacement that AA sent me this weekend. It worked fine when I hooked it up, and I listened to a couple of CD cuts I know well on my cold system. I let the system including the DAP warm up for an hour, then I returned to listen again. I replayed the same two cuts, then moved to another on the same CD. At this point the DAP had been powered up for about an hour and a quarter. Suddenly the right channel died. I muted the preamp and picked up the DAP to check out the conections, which were fine. I unmuted the preamp and warily sat down to listen. Both channels were again operational. About 2 minutes later I heard a loud bang through my right speaker and the right channel went dead again. At this point I'd had all I could handle. I removed the DAP and confirmed that the right speaker was OK after the transient. This is the first piece of gear that has ever catastrophically failed in my system in over 23 years of listening. I called AA next day and reported my problems, and they agreed to refund the unit - kudos to Joe and Matt for great customer service. Now for my listening impressions. Of necessity they are based on about 20 minutes of listening - I normally prefer to listen much longer before forming an impression. System (my Frankenstein) consists of: - Wadia 7 transport - Genesis Digital Lens - Wadia 9 D/A - Krell KRC-HR preamp - Apogee Studio Grand speakers (including DAX electronic crossover) - Pass Aleph 1.2 on the ribbon panels - Aragon Palladium II on the subwoofers System is currently wired single ended, except for the link from the Studio Grand DAX crossover to the Palladium II's, which only have a balanced input. Test CD: "No Frontiers", Mary Black; main track :"Columbus" I consider imaging and spatial detail to be one of the great strengths of the Wadia7/9 combo. With the DAP in place, I did hear more apparent detail, but it came at a cost. My impression was that the entire tonal balance of the system had shifted toward the treble. Bass was there, but it lost some weight, and the highs seemed etched and a bit harsh. The overall sound of the system was thin, and I missed the spectral balance of the system without the DAP. Mary Black's voice lost its warmth and huskiness, and sounded cold, sterile, and high-fi. True, I heard a bit more ambience, but no more than I would get from EQing the highs. I don't know how the DAP would have improved with breakin, but I don't want to risk my speakers to try again. I still wonder what the processor is really doing to the signal. Clearly Whest is having some kind of quality control issue with the DAP-10R. BOA2 got one defective unit and I got two. If you try one be sure you buy from a dealer with good support. My $.02. |