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In Reply to: That information is available posted by Metralla on December 2, 2004 at 18:05:32:
Here's my understanding of why Allen thinks the 9000ES is a better mod platform than the 999ES:The earlier generation Sony SACD machines use a non-conventional, DSD only "current pulse" DAC. CD playback is provided by converting PCM to DSD in a digital filter. Allen's mod to these machines taps the output of the digital filter (VC24 chip) and passes it through a circuit of his design that does low pass filtering and buffering for output. It bypasses the DAC and all the output circuitry, including a ton of op-amps.
The later generation Sony machines use conventional multi-format Burr Brown DACs just like Denon, Pioneer, et. al. So his current mod will not work in these machines. The BB DACs handle PCM and DSD inputs, so there is no conversion from PCM to DSD prior to the DAC. That means the DACs can't be bypassed without losing PCM playback capability, so all existing mods to these machines preserve the BB DACs and therefore don't offer as pure a signal path.
Follow Ups:
...not only can one bypass almost all of the extranious stuff in an original SONY VC24 based player - they also have very direct clock signal paths - using a clock of the correct frequency and feeding it directly to where it's needed. This makes adding a superior clock easy to do, and very effective.The 9000ES even has two different clocks - one for SACD & RBCD, and a completely different one for DVD playback.
However most of the more recent SACD/RBCD capable DVD players have just one clock, and massage this clock signal with all sorts of phase locked loops etc to generate the several different frequencies needed - a great move to keep costs down, but in the process adding all sorts of jitter and other clock related errors. So adding even the best after market clock does little good as it's purity of signal will be 'massaged' as well...
So I say to Jerome, buy the dirt cheap 9000ES, or let me know who's selling it and I'll buy it myself!
Allen
nt
My first reply was to Sordidman, and then I replied to you.
nt
Eric"Julian Dicks is everywhere.
It's like they've got eleven Dicks on the
field."
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