Peavey 30 Upgrade

[westside]

I want to build an amp. I looked into the hardware you need to get, and I said to myself, I said, "Self, why don't you buy a used amp to modify? You'll get a case, a chassis, transformers, a speaker, and you can go to town. It's not an amp you know and love, so go ahead, rip it up!" I found a Peavey Classic 30 for cheap. It's in the basement, tied to the workbench, and its cries of terror do it no good. (Oh wait, that was me playing my guitar.)

So, the plan is to replace most of the guts of it with a new circuit board, made to order by me to satisfy my amp-building jones. I want to make a turret and/or eyelet board, rebuilding the amp pretty much as it exists, and incorporating the mods on the Steve Ahola Blues Guitar website. Plus, I want to try some output scaling techniques, so I want something I can modify/explode without a deep sense of loss. So now, I have made a few discoveries:

1. The thing is cheaply made, using a very intelligent design. for instance, the filaments are powered using a 36 VDC circuit. Using resistors and the filaments themselves, it's a voltage divider circuit delivering 12 VDC to the preamp tubes and 6.1 VDC to the power tubes. This is a cool manufacturing idea, but didn't deliver the standard power transformer I wanted for my project, where the filaments are wired in parallel. OK, drop back and punt. I'll keep that idea.

2. The circuit board actually folds into a 'C' shape. The connection between boards is by a bunch of jumpers, which must have been installed while the board was flat, and then bent when the board was broken (at the break points drilled into the board). Cool for economical amp production, not good for mods. So, that's ok if I want to replace the circuit boards. But, I'm thinking, maybe I want to keep the section of board that has the tubes on it. They are mounted, they fit, there are only 28 jumpers .

3. I need to buy a bunch of resistors, capacitors, jacks, etc. Who is a good supplier?

4. Is this a stupid idea? Ok, never mind, dumb question..

Thanks,

Westside Willie

[newey]

WW-

3. I need to buy a bunch of resistors, capacitors, jacks, etc. Who is a good supplier?

Try Mouser or Digikey. Other sources are listed on the links page.

If you order from Mouser, they'll send you a catalog the size of a phone book every 3 months for the rest of your life.

4. Is this a stupid idea? Ok, never mind, dumb question..

Not at all, I think it makes some sense to start with an existing amp, if only for the cab and speaker. As far as the circuitry goes, you need to be careful that you don't fall into the syndrome of "Grandpa's ax".

You know Grandpa, he always boasted that he'd been chopping firewood with the same ax for 50 years. Of course, he'd replaced the axhead 3 or 4 times over the years, and replaced the ax handle a half dozen times. But it was the same ax he'd had for 50 years!

IOW, you can quickly reach a point where you're better off to build a whole new amp circuit than to do modifications to the majority of the circuit.

[westside]

Thanks for the reply, Newey. I like the Grandpa story. But, you know, if Grandpa thinks it's the same axe, then maybe it is.

I proposed modifying my Blues Jr. in the Power Scaling or Attenuator thread that you answered,

But if I were you, I wouldn't go tearing into the Blues Jr. unless I had considerable experience with modding amps.

So I'm taking your advice, and good advice it is. But I still have my eye on the power scaling idea, and the Peavey is the test bed for that. I like the sound of a loud amp, but my ears are getting to the end of the decibal-hour equation, so I need a way to rock on quietly. Power scaling may be it.

Regards,

Westside Willie

[newey]

I hadn't connected this thread with the prior one about the Blues Jr. Tearing into the Peavey is a better idea, IMHO.

EDIT:I don't know if you saw this thread on the Peavey 30 from last year, there's a discussion of pulling tubes to reduce the power. I know that's not your plan but there is some info there that may be useful to you.

Peavey Classic 30

Further back in our history, there was a more general discussion of tube and speaker swap for the 30:

Xstonr's Classic 30 thread

[westside]

Hey Newey,

Thanks for the info. I had found the first thread but not the second one.

The tube filaments are wired in series, like so many Cristmas tree lights. If you pull any, they all go out. They did that to avoid needing a power transformer with the 6.3 V tap, which makes the amp cheaper to build. But still, it's a very nice design.

Westside