VOX AC50 and old caps/resistors

[Leevi]

I'm repairing an old VOX AC50 which already after some fixes sounds pretty well.

Do you think I could improve the sound even more by changing some caps/resistors to new ones or
is it the better to leave the original parts there?

For more information see the picture.

/Leevi

[LooseChange]

If the parts are good, leave them alone.

[HotBluePlates]

Many people drool over those old parts.. I'd leave them alone.

If you have a capacitance meter, it might be handy to measure the present value of the cathode bypass caps. They will likely have aged and drifted down in value.

The intent is not to confirm that you should change them, but to provide known value that result in the sound you have now. You may want to be able to return to that sound (without the little extra bass of unaged values) if you need to replace them in the future.

[Tiny_Daddy]

On these amps I check all resistors and replace the bad ones with new carbon comp. Heyboer makes a nice replacement output transformer for AC50 and for AC100 and I have replaced several. The film caps are usually OK. If not I use CDE/Mallory 150 series, 630 volts.

[Leevi]

Heyboer makes a nice replacement output transformer for AC50

The OT is probably the last component I'll chance if it works. I think for the transformers
it is quite difficult to find good replacements. I have built several AC50 based amps and
have never got them sound like the original. Anyway thanks for company name (Heyboer) Tiny Daddy!
I have not tried their OT.
/Leevi

[SoundmasterG]

+1 on Heyboer. I used the AC100 OT and choke in a build and it is fantastic. I plan to use more of their products.

I would also only change what is needed in the amp. These are great amps stock and just make it work well and you will be surprised at it's sound quality. They have a strange biasing scheme on the power tubes...cathode and fixed bias at the same time, but when it is setup correctly, it works and sounds fine.

Greg