Outpicking VC24+
I have read Christer's outpicking thread of the VC24+ and Mr. Perez's circuit modifications with great interest. But is there a discrepancy between the two? The outpicking diagram (which illustrates the junction between the DAC and the Current Pulse IC's) shows two tied in pairs.
The first pair: Pin 28 and Pin 25 off the Pulse chip input are tied after the resistors.
The 2nd pair: Pin 27 and Pin 24 are tied after the resistors.
This corresponds to tieing R2(-) and R1(+) together, and R2(+) and R1(-) as another pair.
This illustration (http://www.diyaudio.com/forums/attachment.php?s=&postid=255161) differs from the assignment of inputs in Richard's schematics where it is indicated that R1(-) and R1(+) are tied through resistors, and R2(-) and R2(+) are also tied; making the second half of the input.
My question is, which version is correct? Using the Sony service manual, this indicates, for example R1(-) and R1(+) are on pins 24 and 25 of the Current Pulse input.
Any thoughts or comments would be appreciated!
Trans32
I have read Christer's outpicking thread of the VC24+ and Mr. Perez's circuit modifications with great interest. But is there a discrepancy between the two? The outpicking diagram (which illustrates the junction between the DAC and the Current Pulse IC's) shows two tied in pairs.
The first pair: Pin 28 and Pin 25 off the Pulse chip input are tied after the resistors.
The 2nd pair: Pin 27 and Pin 24 are tied after the resistors.
This corresponds to tieing R2(-) and R1(+) together, and R2(+) and R1(-) as another pair.
This illustration (http://www.diyaudio.com/forums/attachment.php?s=&postid=255161) differs from the assignment of inputs in Richard's schematics where it is indicated that R1(-) and R1(+) are tied through resistors, and R2(-) and R2(+) are also tied; making the second half of the input.
My question is, which version is correct? Using the Sony service manual, this indicates, for example R1(-) and R1(+) are on pins 24 and 25 of the Current Pulse input.
Any thoughts or comments would be appreciated!
Trans32
Attachments
As most of you seem quite experienced with sony xb 940, I would appreciate very much if you could advise on the following noise problem:
After some mods (LC XO Clock, Black gates on the audio board, 2 silver caps at the output and some power supply and ground micro-changes such as grounded copper plates for better separation, etc.) the CDP now operates normally but with very loud high-frequency noice like emergency train brakes or rather a hysterical scream, I guess at about 5-6 kHz.... It seems to me this is a digital noice, although I did not touch the digital board. The noice starts a second after I press play and is much louder (unbearable) than the music, which seems to sound OK.
Please note that earlier test with the clock only (w/o the rest of mods and the clock's own power supply, added later) was ok. I changed the chips, no diffrence, so it is not them.
Another Q: Is it really a good idea to do the LC ZapFilter mod (also hoping it may cure this crazy oscillation???)
Tips will be highly appreciated!
After some mods (LC XO Clock, Black gates on the audio board, 2 silver caps at the output and some power supply and ground micro-changes such as grounded copper plates for better separation, etc.) the CDP now operates normally but with very loud high-frequency noice like emergency train brakes or rather a hysterical scream, I guess at about 5-6 kHz.... It seems to me this is a digital noice, although I did not touch the digital board. The noice starts a second after I press play and is much louder (unbearable) than the music, which seems to sound OK.
Please note that earlier test with the clock only (w/o the rest of mods and the clock's own power supply, added later) was ok. I changed the chips, no diffrence, so it is not them.
Another Q: Is it really a good idea to do the LC ZapFilter mod (also hoping it may cure this crazy oscillation???)
Tips will be highly appreciated!
Sony SCD-1 or 777ES S-TACT Bypass is Noisy?
Has anyone noticed when they bypass the Sony SCD-1 or 777ES S-TACT that it is noisy?
Have you noticed a low level noise during quiet moments of a recording? It sounds like digital hash and a bit like birds chirping. It is quite intrusive with low level recordings or recordings with a lot of quiet like classical. Possibly some IM artifact? Whatever the S-TACT does, it appears to be removing this noise, since I do not hear it out of the stock outputs.
If you have heard this when bypassing the S-TACT, did you find a solution and what was it?
I have found that one channel is slightly noiser than the other which is helping me to pinpoint. I reversed the inputs to the VSE and the noisier channel followed the reversed input, so it is not the VSE causing the problem.
I have connected the outputs of the player directly to headphones and I still hear it, so I don't suspect IM distortion in the downstream components.
I had read somewhere that the VC-24 can get a little noisy when overloaded. Perhaps this is the issue since it is feeding into both my VSE as well as the S-TACT. I may remove the 4 331ohm pads to remove the S-TACT load and see if this solves the problem. Can I do this without impacting the operation of the player, other than disabling the stock outputs for DSD of course?
Do you think this will solve the problem, or will this problem only be solved by the S-TACT?
Thanks.
Has anyone noticed when they bypass the Sony SCD-1 or 777ES S-TACT that it is noisy?
Have you noticed a low level noise during quiet moments of a recording? It sounds like digital hash and a bit like birds chirping. It is quite intrusive with low level recordings or recordings with a lot of quiet like classical. Possibly some IM artifact? Whatever the S-TACT does, it appears to be removing this noise, since I do not hear it out of the stock outputs.
If you have heard this when bypassing the S-TACT, did you find a solution and what was it?
I have found that one channel is slightly noiser than the other which is helping me to pinpoint. I reversed the inputs to the VSE and the noisier channel followed the reversed input, so it is not the VSE causing the problem.
I have connected the outputs of the player directly to headphones and I still hear it, so I don't suspect IM distortion in the downstream components.
I had read somewhere that the VC-24 can get a little noisy when overloaded. Perhaps this is the issue since it is feeding into both my VSE as well as the S-TACT. I may remove the 4 331ohm pads to remove the S-TACT load and see if this solves the problem. Can I do this without impacting the operation of the player, other than disabling the stock outputs for DSD of course?
Do you think this will solve the problem, or will this problem only be solved by the S-TACT?
Thanks.
http://web.archive.org/web/20070219232432/http://perez.r.free.fr/XB_out.JPG
http://web.archive.org/web/20070219232606/http://perez.r.free.fr/XB_out-DC_servo.JPG
http://web.archive.org/web/20070219232458/http://perez.r.free.fr/XB_out_fet1.JPG
http://web.archive.org/web/20070219232744/http://perez.r.free.fr/XB_out_fet_dc.JPG
http://web.archive.org/web/20070219232618/http://perez.r.free.fr/XB_out_fet_dc_xfr.JPG
http://web.archive.org/web/20070219232819/http://perez.r.free.fr/XB_out_fet_dc_0v.JPG
Sometimes you can find lost pages at http://www.archive.org/web/web.php
aparatusonitus,
the first schematic with AD828 are differential stages but the others with fet are only a buffer with DC compensation ?
If you allow a transformer on the signal path why not use a solution like the Perugini idea ?
http://www.audiodesignguide.com/HiResolution/EMU0404/LL7903sch.jpg
references:
1) http://www.audiodesignguide.com/doc/pag1.jpg (see other pages)
2) Hi-Resolution System 192KHz 24bit with EMU 0404 USB
the first schematic with AD828 are differential stages but the others with fet are only a buffer with DC compensation ?
If you allow a transformer on the signal path why not use a solution like the Perugini idea ?
http://www.audiodesignguide.com/HiResolution/EMU0404/LL7903sch.jpg
references:
1) http://www.audiodesignguide.com/doc/pag1.jpg (see other pages)
2) Hi-Resolution System 192KHz 24bit with EMU 0404 USB
aparatusonitus,
Are these the points where you have got the output signal from DAC ?
http://www.audiodesignguide.com/HiResolution/XB940out.gif
(red & blue points)
Are these the points where you have got the output signal from DAC ?
http://www.audiodesignguide.com/HiResolution/XB940out.gif
(red & blue points)
Last edited:
Patrick
would you give us a little more Info on your implementation of dc servo buffer http://web.archive.org/web/20070219232819/http://perez.r.free.fr/XB_out_fet_dc_0v.JPG
can you explain benefits of this complicated circuit compared to http://web.archive.org/web/20070219232458/http://perez.r.free.fr/XB_out_fet1.JPG and http://web.archive.org/web/20070219232744/http://perez.r.free.fr/XB_out_fet_dc.JPG
also what are your passive filter values
regards
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