a little OT - Randall amps schematics?

[space_ryerson]

I've swapped power amps and speakers; the difference is definitely somewhere in the preamp.

[Marcos - Munky]

Well, then I don't know. The only things that are different in the preamps are the two caps? The change in the values is very little, and I believe that this won't change the sound.

[space_ryerson]

That's why I'm scratching my head about this. I do know that the only amp that has been used non-stop is the better sounding Randall, so maybe the caps in that one are in better shape? The transistors, diodes, cap values, and resistors are all the same. It does look r51 has been changed, but that shouldn't make a difference.

There's a mild difference on the cap on the presence control, but that doesn't seem to be enough to make any audible change. All of the resistors are the same. It looks like I'm going to have to test it all out with my DMM. How do I test for capacitance? It said nothing about how to test it in the manual (fluke 73).

Also, I have an rg-80 classic, which is from the washburn era that hisses and has a really loud noise floor when running. Could that be the filter caps in that one?

[Marcos - Munky]

Not every DMM have capacitance meter. About the RG-80 problem, I believe the problem is caused by some caps, but don't know which ones. Create a topic about this, I'm sure that there are guys that can help you to solve this problem.

[Marcos - Munky]

I added the preamp schematic in my site.