Output cap on a CD player

[rabbitz]

I've got a Sony CDP990 I've had since 1990 and even though I've had newer players which have come and gone, this always returns to the rack as the sonics are very appealing.

I changed the output op amps from 5532's to OPA2134's which gave a nice improvement in overall detail and clarity. The original output caps (C406 in the schematic) are Elna Duorex II 47uF 63V and would like advise on whether to change these as they might be getting past their used by date. I'm leaving the rest of the player as original.

a. Change to Nichicon Muse Fine Gold 47uF 50V which I have.
b. Change to a MKT or MMK of 1uF???
c. Put in a link and have no cap but I can't always be sure the amplifier that comes next in the chain would have an input cap.
d. Leave the Elna's in there.

Any advise would be appreciated.

[dsavitsk]

Originally posted by rabbitz
a. Change to Nichicon Muse Fine Gold 47uF 50V which I have.
b. Change to a MKT or MMK of 1uF???

How about both of these? Put in the 47uF caps to get the proper rolloff frequency, and bypass it with a decent film cap for the sonic improvement. You could also pick up something like a solen film cap that is 47uF for about $13 if you don't like bypassing.

-d

[georgehifi]

Stick with one cap, if you can, as bypassing coupling caps causes as strange smearing where both caps are doing the same job but at different speeds because their internernals do things at different speeds. (it good to bypass power supplycaps)

I would say get a if staying with electrolytics get a NX black Gate bipolar 47uf x 6.3v the voltage should be enough
as I've rarely see offset voltages of over 1v 0n cd players so 6.3 should be ample just check what your getting now dc offset wise before the Nichicon.

Or if you can find them a big say 10uf no less polypropylene cap from Auricaps or Solen.

Cheers George

[baggystevo82]

What are you driving with it? Even with a low input impedance SS amp 1uF is likely to be plenty, opening up lots of potential film n foil caps. Might be worth checking the input of the preamp for coupling caps too, no point having two lots of caps...
Steve

[georgehifi]

I would stay above 10uf, if you ever try say a passive pre that commonly has sometimes a 10k input impedence your low frequency roll off will still be -3db at 1.5hz so it safe for all types of pre's, I've even seen active pre's with inputs of 10k so a minimum of 10uf is a safe bet.

Cheers George

[rabbitz]

Originally posted by baggystevo82
What are you driving with it? Even with a low input impedance SS amp 1uF is likely to be plenty, opening up lots of potential film n foil caps. Might be worth checking the input of the preamp for coupling caps too, no point having two lots of caps...
Steve

The amp is an AKSA 55N+ with an input impedance of 47K. There's an active pre in between but still not finalised as I'm testing OPA134, OPA627, OPA2134 and different layouts.

I've had the Black Gate NX at the back of the mind and remember the excruciating burn in of 150 hours with the AKSA, but well worth it in the end.... Hugh's always right. With a CD not so bad as just leave it on repeat for a week. Could even try the cap rack again to do some pre burn in but no success with that method previously.

Thanks for the advice guys.

[georgehifi]

What have you measured as far as the dc offset goes, as the original ne5532 has dc offset that needs a dc blocking cap, but since you changed to OPA2134 these may be fet input ic's and if so may have very little dc offset, if so and they are giving say below 10mv of dc offset you may want to try having no cap at all (ie: dc coulped) and that sounds better than any cap, just do'nt turn your player on or off while the rest of the system is switched on or you may get swicthing thumps. Just leave it on all the time.

Cheers George

[rabbitz]

George

Needs a cap as the offset is 66mV (100mV specified in the service manual).

Tried the Nichicon Muse and did give a noticeable improvement to the dynamics so added to the improved detail and clarity from the OPA2134, it's worked well and A$18 all up.

I'm going to order some 47uF 6.3V BG NX from Hi Fi Collective and some STD BG for the op amp power caps. They're 470uF 35V at the moment but I'll get some 470uF 16V as it's only got 5V rails.

Thanks for all the advice.

[georgehifi]

So you say that now with the OPA2134 you have 66mv, if that's the case then you will need a blocking cap


Cheers George

[Gasho]

Change OPA2134 , with AD828 , than change all resistors in signal distribution with Riken or Dale RN60 , as output cap you can put Mundorf Mcap 3.3-4.7uF . This will be more than you need to 20Kohm input resistance of your amp.


What about power supply in your player. Did you change diodes in Greatz. In digital PS path try to put OsCon caps near DAC/Filter chips. Before that pull out all factori caps (electrolitic/tantal/ceramic).