I replace all or the Electrolytic caps on my amp. Since we don't have many people selling parts any more I got what I could from a local repair shop. I selected values based on what he had the most of, not necessarily what came out of the amp. I never went below the voltage on the original parts but I went for higher values. I have never really worked on High quality audio circuits, mainly communications grade (300Hz - 3000Hz) audio.
To be specific, I replaced all of the 150uf 50 volt caps with 330uf 63 volt caps on both the rectifier and the GP board. The 450 volt caps were the same value as was in the amp. Will this change the sound, tone, characteristics of the amplifier?
I have looked through both this and the old forum and people talk about keeping the parts exactly as the original but I never found any reference about why, other than just to keep them the same. Meeting the required voltage rating is a given, increasing the value should just make a better DC filter. Thanks Mike
No change
Well, a guitar amp is not too much different from 300Hz-3000kHz audio :) - an extra octave at either end and you're there.
In this particular case it should make no difference with the changes you made. The caps in the audio pathway, on the other hand, should remain close to the original design if you want the amp to retain its tone (that's the short version of that explanation anyway). You could in theory put filter caps in that would strain the diodes and transformers with their in-rush current but I don't see your 330uF caps being a problem. That being said, I have never had a problem getting 150uF caps. All the online retailers have them. I would be afraid to purchase electrolytic caps at a physical store anymore, you never know how long they have been sitting.
Cheers,
Lars
Thanks for the replies. I
Thanks for the replies. I didn't see how the change in values of the caps would change anything since they are not in the signal path. Everyone seemed to be so worried about maintaining the original value so I just wanted to make sure I wasn't missing something. If there is a next time, I might try to keep it more original just for original sake.
I now have the names of suppliers that I have found on this web site. Haven't thought about Newark in over 20 years. Glad they are still around. The owner of the business I got my caps from maintains stock for his own use. Hopefully he would not use old parts in his industrial repairs. I was able to get the caps and do the job in one day. I am now in a wait mode for tubes and 1 ohm resistors and a few other things to try to get rid of my distortion and low audio in Low Power mode. The problem is on both channels so I hope it is something funny with the 6ca7s, all of the voltages seem correct in both modes. Keep you fingers crossed for me and thanks again.
This has been fun. Wish I had another one to work on when I finish this one.
Mike
Try Mouser or Newark
Try Mouser or Newark Electronics, they usually have everything you need in stock and ship fast.