Just had a quick go-over with the dmm on the amp. Most of the caps in the signal path are Pana FC's.... Is that bad??? could they be the 'bright' problem???
Just read about caps 'burning in' , could my problem be impatience?? they're all relatively fresh and had little use as of yet.
nad, as a first step I'd replace signal caps with Elna Silmics. These are warm and smooth sounding caps, but still have good detail. Hopefully the tonal balance should be more to your liking. Also, what opamps does your CDP use?
They could be a factor yes. A better cap to use is the Wima film capacitor. Nothing smaller than 3.3uF should be fine. You will have caps in the signal path right at the RCA input sockets. You will probaly also have additionl caps further down the singal path. Check the premap stage input, and the poweramp stage input. You should also try and locate the poweramp 'feedback' cap. Once you have located these try replacing them with Wima film caps, and for the feedback cap try a 100uF Tantalum.
This is hard for me to help you with without having the schematics, you can trace with the DVM, maybe use a thin marker pen to literally trace out the signal path from RCA to poweramp stage, marking the PCB with a line. Any electrolytic caps directly in this path -ie; signal passes in one leg and out the other - are your DC blocking caps. These are the ones to change to Film's. For the feedback its a bit more tricky.
You really need to have the service manual or schematics so you can identify which components are the key ones and most likely to make a difference when upgraded or changed.
With regard to 'burn-in', you may find things improve with time. Leave the amp and CDP powered up and playing on repeat overnight. See if it improves.
Thanks again.
I was thinking about changing the caps for Elna Silmic II's. They're reasonable in price and readily available, what do you think, or are films that much better??
I still don't understand the 'feedback' part, what is it, what's it for, what does it do? why would it be dificult??
Thanks
It took alot of effort to fit them though, had a hard time soldering them to smt, then they fouled the chassis so I had to drill and grommet 2 holes.
Its just a cap in the amplifiers feedback loop, I'm not sure what it does but changing cap types in this location always seems to have a dramatic effect on the sound.
With regard to Wima Film caps, they will probably have a more open sound than the Silmics but that might not give you the right balance. You need to compensate for the overly bright sound so the Silmics might give a better overall tonal balance. They are worth a try in the Feebback position also.
Thanks again, i'll jot the values and order the Silmics. How do I know which is the feedback, will it be in any 'usual' position?
I was checking the caps with my dmm from the top, Dont know if I did it right but if any of a specific caps legs weren't to ground then I guessed it's in the signal?? am I wrong?
Back to the CDP. Come to think of it, when I started pulling caps I noticed the only branded ones were elna's (not silmics) and they were in the signal path, I changed them for Nichicon Fine Golds. Maybe a bad swap?
Think I've found the feedback caps....... 2 large caps have the positive pin to ground and the neg to the power amp.
For Op Amp, I'd try a dual OPA2132. Or OPA132 if they are a pair of singles.
If you put low ESR caps around your regs, it can have a big effect on the sound.
See here:
Using 3-pin regulators off-piste: part 1
I've only read the last couple of pages, but found out myself that shot-gunning a load of FCs or whatever into a piece of kit isn't the best way to go! 😉
Good luck!
Jon
If you put low ESR caps around your regs, it can have a big effect on the sound.
See here:
Using 3-pin regulators off-piste: part 1
I've only read the last couple of pages, but found out myself that shot-gunning a load of FCs or whatever into a piece of kit isn't the best way to go! 😉
Good luck!
Jon
OK, Im just having a look at the pics to see if I can spot them. Are the caps you found 100uF or thereabouts?
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