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In Reply to: RE: cMP - the open source high-end Memory Player posted by cics on December 30, 2007 at 05:42:01
I tried using an extenal clock for cmp (Oppo dvd player)and found a nice little sq improvement. Most recently cics recommended another pc psu unit to drive all the so called 'dirty power consuming devices'. So I connected another pc psu unit to P4, all my drives and lo and behold got the sq pop cics talked about. When using an external clock to drive juli@ I got the same (but smaller) sq pop. The sq improvement makes sense to me because the juli@ clock is no longer drawing current from the p24 line. However there is an issue. When used in this fashion as soon as I shut off my battery feed (3.3volts) to Juli@ I lose control of the cursor via the mouse. It goes away upon reboot but even if I switch back to internal clock before shutting down the battery feed the cursor/mouse locks up so it always necessitates a reboot. Its enough of a nuisance that I have fallen back to only using the internal clock. But if there is a way to avoid the reboot the external clock would be a permanent tweak imo.
For Buf32s users I recommend damping the Sabre chip with a bit of gooey substance right in the top/middle of the chip (avoid touching any of the pins on the chip to prevent shorts). This improved sq very significantly in the upper mids and soundstage area. I used some black tacky goo I had on hand. Mortite did not work as well. Goo-ier the better.
Follow Ups:
Maybe a stupid question, but how did you determine the clock freq. to use?
RayBan
Just clicked on 192K and chose either INT or EXT on the juli@ panel. Is there another way?I use 192K upsampling for all files.
The trick to get the right clock with my oppo is to run a 24/192 disc in the dvd player then the clock will be set to 192K and as long as you run just this one clock rate you are set.
Edits: 05/02/10
By running a DVD to ensure 192k SPDIF output, you're adding to jitter rather than reducing it.
A better way to improve Juli@'s XO is using Mihaylov's approach of replacing it's XO entirely.
While I agree 100% that relacing the oscillator is optimum I just wanted to try the experiment. Also I don't really run the dvd while playing cmp^2. I run the dvd then stop it which tricks the dvd output to be set @ 192K. It doesn't really matter because of the 'locking of the mouse cursor' problem this is impractical for me. I was just hoping I could find a way to avoid the locking problem.
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