Want to bypass opamps in Sony Cd player

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ChopperCharles

ChopperCharles

Member
Joined 2008
choppercharles.com
#1
As a test DIY project, before I open up my SACD player I've opened up an old Sony 5 disc changer. I want to bypass the opamps, but I'm having a hard time determining which chip is the DAC.

I've got a CXP50116, which appears to control the display on the CD player.

I've got a CXD2500BQ, which might be a DAC, but I can't tell.

I have a CXD2560M (24pins), which I cannot find a datasheet for.

I have one final small chip which the number is rubbed off. It looks like it says "PULSE" and CXD25678 OR CX02567B or something. The number is really difficult to read so I could be way off. It's a 28 pin chip.

All of these are surface mount btw.

Any idea which of these is the DAC, and which pin I can pull L and R audio off of to wire to capacitors and then to two new chassis-mounted RCA jacks? The plan is to use a tube preamp stage between this CD player and my amp.

Thanks!

Charles.
 
#2
Hi. The 2500 is a digital servo, EFM and error correction processor + a lot more besides, e.g. variable speed playback if machine has that option. You need a circuit diagram ! You can't really just bypass or eliminate opamps, the output from the DAC is TOTALLY unsuitable to feed direct into an amplifier. Further the opamps are usually used to implement a "reconstructive" low pass filter, and without this this the audio signal will be grossly distorted.
Regards Karl
 
#3
I agree ... not a good starting point.

CXD256xx are differential output DACs with noise shaper and are not an easy option even if you find a diagram. Filtering is required.

Try and find an old Marantz or Philips (not bitstream)


Andy
 
#5
Charles, I don't think you're comparing like for like. Your old Sony almost certainly uses a DAC that provides a current output and this is converted via an OpAmp to a voltage (I/V convertor). All these stages are required. From here there will probably be another OpAmp that is used for implementing the low pass filter. I quickly looked at the link you provided and the first thing mentioned is that this mod is possible because the output from this particular DAC is a voltage source, not current. If you can provide a circuit for the SACD player we might be able to advise better.
Regards Karl
 
#6
Well, if that's the case... I might be more interested in adding an SPDIF output to the old 5 disc changer and using an external DAC.

I guess I just got excited between the SACD player mod and the Playstation mods on this site and decided to see if I could hack this old player as well. Looks impossible, so I guess I'll put it back together and just mod the SACD player.

Charles.
 
#7
I have old CDP Sony M43, not able to play. Control board is OK.
How can I drop-in XMOS XU208 usb to i2s to convert CDP to a DAC?

CXD2560M
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Diagrams
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