Classic 30 upgrade

[bigdaddyweed]

Has anyone ever upgraded a Peavey Classic 30 to class"A". Is it even possible, or feasible? :? And how about the cost and results? I've been looking at several class "A" amps, and will probably purchase one, as soon as I sell a couple of other amps. So I thought this could be an option to consider, since I like the C-30's tone, and wondered if converting it to class "A" would work.

Thanks................Weedman

 

[ylo]

You can modify a fixed-bias push-pull output to cathode bias with a couple of resistors and capacitors. You can even add a switch to change the amp back to fixed bias on the fly. The wiring is similar to the way preamp tubes are wired. You can find the mod on the web, or you can figure it out for yourself with a book on tube amp design and the data sheet for the output tubes you are using.

What the marketers call "class A" is in reality cathode bias in all except for single-ended amps. For example, the Vox AC30 isn't really Class A. It is Class A/B cathode bias.

Anyway, isn't the Classic 30 already EL84 cathode bias? To make it true Class A, you would need to disable the audio through all but one tube. This isn't so easy using the same transformer. Randall Smith has figured out a way to do this in the Lone Star Special (5 W mode), but as far as I know, nobody has yet posted the schematic to show the trick he uses.

 

[t0aj15]

And how weird/stupid is it that Peavey doesn't offer a 50 watt head version of the Classic amp?

Not sure about now, but I traded in a Peavey Classic 50 head (tweed) when I bought my Boogie Mark IV.