View Full Version : techniccs sl-pg477a mash cd player opamps which to changer
Being a Technics fan i decided to try some MASH cd players - I got 2 - Technics sl-p477a and pg440a.
Which opamp do I change.
most benefit will come from applying the high performance op amp after the converter in the signal chain. from TI:)
4560? opamp not LM833N
P477A pcb
http://i63.tinypic.com/33diovn.jpg
PG440A
http://i68.tinypic.com/14mcaxx.jpg
thanks Sam :D
Leave them in, and cut out that muting transistor circuit. Q803 and Q804, snip them out.
This is a nice article on muting transistors, it is a good upgrade: http://margo.student.utwente.nl/klaas/audio_cd.htm
Put in some 5532's. I have never had good sq with the LM 833. I have tried some real expensive ones, but the 5532's is as good as it gets imo.
Hi Neil:)
Thank you for the inexpensive mod with the muting transistors, and the link. I had Marantz CD65II modded with new caps etc, but had muting transistors done, there was never any clicks between tracks.
Hi Johan :)
Thank you for the opamp suggestion. I read that also on navguy opamp reviews that the LM833N didnt beat the 5532, it was only the national LM4562 that was better. I think the LM833N was one of the worst. You are taking of TI 5532
I have also tried the LM 4562. Not impressed. I have modded some cdp`s during the years, and always found the LM 833`s to be bad performers. I suggest you solder in some IC-holders to make easy swaps. Op-amps sound different in different circuits, and it is possible that the LM 833`s is ok in your cdp. The circuit is designed for them after all. Good luck anyway what you do!
my sl-pg490 has had a NOS conversion,not sure if its relevant to this thread but it sure sounds good.
Put in some 5532's. I have never had good sq with the LM 833. I have tried some real expensive ones, but the 5532's is as good as it gets imo.
Specifically the older Philips / Signetics ones.
I have also tried the LM 4562. Not impressed. I have modded some cdp`s during the years, and always found the LM 833`s to be bad performers. I suggest you solder in some IC-holders to make easy swaps. Op-amps sound different in different circuits, and it is possible that the LM 833`s is ok in your cdp. The circuit is designed for them after all. Good luck anyway what you do!
Me neither. Circuits are often optimised around these older, slower opamps, so putting in a fast one or 'ultra-low distortion' one can just make the sound change, and not for the better. I would work on the power supply quality instead.
If you really want to improve the output stage, then it needs to be completely replaced.
For example here is an optimised for MASH DACs (the voltage output circuit in the article) tube output stage: https://www.scribd.com/doc/105561243/Thermionic-Valve-Analogue-Stages-for-Digital-Audio-A-Short-Overview-of-the-Subject-by-Thorsten-Loesch
I have also tried the LM 4562. Not impressed. I have modded some cdp`s during the years, and always found the LM 833`s to be bad performers. I suggest you solder in some IC-holders to make easy swaps. Op-amps sound different in different circuits, and it is possible that the LM 833`s is ok in your cdp. The circuit is designed for them after all. Good luck anyway what you do!
Hi Johan
The LM833s do seem pretty good in the current set up, certainly pretty detailed sounding on the recordings, iwasnt expecting much looking at the pcb set out, compared to the older cd players i have.
my sl-pg490 has had a NOS conversion,not sure if its relevant to this thread but it sure sounds good.
Hi Jamie
Thank you, i would like my ones NOS though. Its a different player though.
If you really want to improve the output stage, then it needs to be completely replaced.
For example here is an optimised for MASH DACs (the voltage output circuit in the article) tube output stage: https://www.scribd.com/doc/105561243/Thermionic-Valve-Analogue-Stages-for-Digital-Audio-A-Short-Overview-of-the-Subject-by-Thorsten-Loesch
Hi Neil
I plan to use silmicII, higher grade capacitor and films in the power supply, maybe diodes also to improve there, wimas in place of the ceramics around the DAC and opamps. With the muting transisotrs? I just desolder them out and solder the holes over? I wish i could understand that article, I will have to read into it more. I think the power supply as you said and thicker wire from PSU pcb to main PCB also, over the ribbon cable
Hi Johan
The LM833s do seem pretty good in the current set up, certainly pretty detailed sounding on the recordings, iwasnt expecting much looking at the pcb set out, compared to the older cd players i have.
Hi Jamie
Thank you, i would like my ones NOS though. Its a different player though.
Hi Neil
I plan to use silmicII, higher grade capacitor and films in the power supply, maybe diodes also to improve there, wimas in place of the ceramics around the DAC and opamps. With the muting transisotrs? I just desolder them out and solder the holes over? I wish i could understand that article, I will have to read into it more. I think the power supply as you said and thicker wire from PSU pcb to main PCB also, over the ribbon cable
No need to solder, just find the muting transistors and bend / cut them out. This defeats the circuitry and stops the horrible parasitic capacitance effects that sit on the sound. Your PCB will be labeled.
Also, it is impossible to do a NOS conversion on a MASH DAC because oversampling is what makes it work in the first place.
:) Thanks Neil
I de soldered them the other day, sounds great, i really like the MASH DAC. I think opamps are actually suited to the player, so maybe try some SilmicII caps and Nichicon, and maybe wimas to replace the ceramic?
If you replace the ceramics, use the smallest WIMAs you can find. Trace inductance matters a lot here, so don't be putting large size caps in, and keep the voltage rating down. Silmics are good for your opamp decoupling caps, I would use 100uf / 25v.
Also, a leftfield tweak, *carefully* mould a lump of blutack to cover your clock crystal.
Hi Neil,
Thank you. i am trying to keep as close to the original voltage of 25v of the ceramics, saw some 63v
http://au.mouser.com/Search/ProductDetail.aspx?R=MKS2C031001A00KSSDvirtualkey5 0520000virtualkey505-MKS2.1%2f63%2f10 or maybe 2.5mm
The tiny black are bps 22uf 16v, maybe 100uf 25v Muse ES. Around the DAC 330uf 6.3v, either 6.3v or 10v silmicII there. Thanks for the tip around the clock, will get some blutack and cover it up. :) opamps, closest is 100u 1** edit actually is 10uf 16v, my mistake **, and the other opamp they are 22uf bps
http://i65.tinypic.com/2qukmx2.jpg
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