So I will.
Yesterday I finally found the time to perform surgery on my CD player, a CD880.
Among the NE5532 opamps I exchanged for the AD826's (and sockets!) also other work was done. Decoupling by chokes instead of resistors, increased caps (Vrefs of the TDA1541A S1 now have 3300uf muse gold caps) and a DEM-mod (thanks to the excellent thread by John of ECdesigns).
I choose the approach of listening, implementing a single mod and listening again and kept record of my findings.
Work sequence:
1) SAA7220 powersupply modded. Cleaned up some mess and relaxed the soundimage somewhat.
2) DEM-mod. Added more subtility and detail to the soundimage.
3) Power supply TDA. Losing some of the harshness and a more coherent sound image.
4) AD826. Game changer... soundimage now is dynamic, relaxed and "analogue", no harshness at all.
CD upgrades...
Hi esgigt, That is excellent. Make a change and then a listen. That is what I do as well. John ECDesign's has done use all a great service. I use his decoupling method. John actually moved away from locking the DEM to the bitclock. Myself I use 120 pF between pin 16 and 17. That puts the DEM at 705 Khz, and that will sync up with the bitclock. However there is nothing wrong with his earlier DEM mod. Power supply is critical because the SAA7220 is actually rather poor. Sadly the only game in town in a CD player. AD826's are an excellent choice. I'd let things kind of settle in before making any other changes. Enjoy!
That's the plan, Torchwood... later the TWTMC will join the setup.. but I'll have to make some arrangements for it's power supply. Also the mute-transistors will go, but I didn't like to disassemble the machine yet, otherwise I can't reach them.I'd let things kind of settle in before making any other changes. Enjoy!
Had to demolish the 5532's too because they were hard to desolder.
In the meantime i'll have to solve a grounding hick-up in the pre-amp
TWTMC?
Sorry to hear about the grounding issue. I have been there.
TWTMC? Yes... The easy way is to clip the op amps out and unsolder each pin one at a time, that will prevent the traces from lifting as well. A 5532 isn't by today's standards state of the art so don't sweat that.That's the plan, Torchwood... later the TWTMC will join the setup.. but I'll have to make some arrangements for it's power supply. Also the mute-transistors will go, but I didn't like to disassemble the machine yet, otherwise I can't reach them.
Had to demolish the 5532's too because they were hard to desolder.
In the meantime i'll have to solve a grounding hick-up in the pre-amp
Sorry to hear about the grounding issue. I have been there.
Very nice...
Something I should look into as well. SD card storage is rather interesting. Thanks for posting your player. Nice work!
Found it...
http://www.diyaudio.com/forums/digi...ow-phase-noise-jitter-crystal-oscillator.html A low jitter clock.
http://www.diyaudio.com/forums/digi...ow-phase-noise-jitter-crystal-oscillator.html A low jitter clock.
Eh, I think the point was missed completely.
When transistor is overdriven, the wave clips (approaches squarewaves).
I presume VFB OpAmps do this. What about current mirror section on 844 OPAmps though? Does it show 'gradual' non linear distortion when driven to extreme, similar to some certain tubes do? Apologies I was not clear enough earlier in my question.
When transistor is overdriven, the wave clips (approaches squarewaves).
I presume VFB OpAmps do this. What about current mirror section on 844 OPAmps though? Does it show 'gradual' non linear distortion when driven to extreme, similar to some certain tubes do? Apologies I was not clear enough earlier in my question.
Researched the hum problem this afternoon... pulled the scoop out and....
I measured no hum on the Amp (Moscode 300) when isolated...
I measured no hum on the pre-amp, when isolated...
I measured no hum on the CD player...
But all of them connected resulted in hum, even with the Amp disconnected, and the amount of hum depended on the volume setting...
So, now I checked out the cables and connectors, and.... darn... the ground solderings did loosen on all connectors
fortunately a rather straight forward, but uncomfortable, job...Hum...
Hi esgigt, Glad you found the grounding issue. Moscode... Have a highly modded Moscode 600. It has at least one failed Mosfet in one channel. My cousin changed to 6FQ7's as I remember. After getting the Class D Audio power amplifier from California I haven't made any efforts to fix that although I should do it. Another project for next winter. I switched to locking RCA's and have to take care not to over tighten them.Researched the hum problem this afternoon... pulled the scoop out and....
I measured no hum on the Amp (Moscode 300) when isolated...
I measured no hum on the pre-amp, when isolated...
I measured no hum on the CD player...
But all of them connected resulted in hum, even with the Amp disconnected, and the amount of hum depended on the volume setting...
So, now I checked out the cables and connectors, and.... darn... the ground solderings did loosen on all connectors
