The Amp Garage

I have a new push-pull 6v6 build that I'm battling with. Right now it's 6SJ7 -> Vol. pot -> 12AX7 -> tone stack -> PI There's a buzz/hum that gets louder as I turn up the volume pot. With no guitar plugged in, it's not too loud. With a guitar plugged in, it's significantly louder. I assume that the...

I might go for that too... When we're on the subject of trim pots.. Is there any reason why the OD entrance pot should be an internal trim pot and not a panel mounted pot that can be adjusted from the back? The way it is now, there seems to be only one "correct" setting for this pot, since you have...

I have a new push-pull 6v6 build that I'm battling with. Right now it's 6SJ7 -> Vol. pot -> 12AX7 -> tone stack -> PI There's a buzz/hum that gets louder as I turn up the volume pot. With no guitar plugged in, it's not too loud. With a guitar plugged in, it's significantly louder. I assume that the ...

I have a similar story. I was getting a warbling sound on notes up around the 12th fret. Someone suggested I lower the pickups - bingo!

Randall Aiken says he doesn't deal with UPS - only Fedex or one of the freight haulers. Good enough for me. I've seen guys gripe about Fedex, but UPS seems to be a much bigger offender.

Well, try it and just put the resistor in parallel with the standby switch. That will give you your B+ you want. For the test you won't have the standby switch. David, I understand what your saying but the sag the rect tube will induce, what 50 votls? This in series with the 20 volt drop on what he...

Kevin loves slick switching.

If I may prove my ignorance here....what is the point of putting teflon tubing on the leads of each and every component, a la Matchless? I'm quite impressed by it, but I don't know the technical reason for why it is done. component leads are no different than wire - they're just putting on insulati...

Nice build. It's a really clean look.

A friend found a Univox bass head cheep, only it has no volume. I opened it up and found the impedance switch completely fried, almost melted down. I disconnected it and wired in a jack directly and it sounded great. So I bought a replacement switch, and while I was at it I replaced the 4 speaker j...

Just a cautionary note here: lowering B+ with a resistor in line is fine for lower powered amps that run Class A or heavy AB, like the AC 30 does. This is because the current draw doesn't vary much from idle to full output in these classes of operation. Even so, the lower the B+ voltage drop the be...

Anyone experienced with putting mosfets in eyelet board construction amps? I'd like to use one as a cathode follower as in the Mosfet Follies article. The leads are pretty close together, so I'm not sure how to secure and solder them into the circuit.

Nice. Right now, at the first cap off the recto I'm seeing about 347v. Ideally, I'd like to have about 320v or so.... So, in that case, with an AC30-ish power section, wanting about a 20v drop, I'd need about a 100 ohm, 10w resistor, right? Looking at the data sheet, it's more like 140mA for four E...

That's a lot of voltage to drop. A resistor in the B+ line would give you huge sag, which I doubt you want for a bass. You can drop it at the CT with zeners, but you'll be dissipating a lot of heat in the chassis. If it were me, I'd bite the bullet and get another transformer. Hoffman sells a toroid...

Ballpark - 200mA x 20V = 4W

Again, I'd go for a 10W resistor for a safety cushion. Try a 100 ohm resistor. 50 ohm for a 10V drop.