The Amp Garage

Howdy, Pretty new here myself. I've got a ton of amp and tube books; some I still use all the time; some have served their purpose. KO'Cs TUT books are pretty cool: TUT1 has some "introductory" info that will still leave you scratching your head, plus a lot of info on using solid-state devices if yo...

On some of the amps Mike Holland used to build, he had a three-wire power cord with a proper safety ground, plus a film cap to ground on the neutral side, a film cap to ground on the hot side AND a film cap to ground from the B+ at the Standby switch. Obviously trying to accomplish something. I thin...

I recapped an Ampeg V-4 once. These things have two multi-section "can" caps wired in series to get the voltage rating up. Of course, this puts half the B+ on the metal housing of one of tha caps. Obvious, once you look at the schematic, which I hadn't done yet. I was doing someting that involved re...

By the way, welcome to the garage. I feel honored that your first couple of posts are for my benefit, so thanks for helping me out. Thanks for the welcome. One of the few sites where I actually felt like jumping in. Solving these maddening little puzzles is really kind of fun. And it feels so good ...

Are you sure the hum is 120 cycles? When you disconnected V1a, did you ground the input to the volume pot (the wire that originally came from the tone stack)? If not, you have a little antenna that will pick up the 60-cycle hum that is ubiquitous -- same thing as an amp where the input shorting jack...

Also, when all the tone stack knobs are at zero and I sweep the volume from zero to full, the hiss will be quiet and then swell and then go back down when it reaches the end with the grounded tone stack. I guess this means that at least some hiss is coming in from the volume pot, the bright switch,...

I've never really been a fan of running heaters off DC -- more trouble than it's worth IMO. Plus, elevating the center tap to +40 or +50VDC always seems to do the trick. One thing I noticed in looking the Francesca pics is that the V1 and V2 heaters are wired out of phase. Even when twin triodes are...