The Amp Garage

I have to agree with the two-point grounding scheme. I use 16 awg (from salvaged ROMEX) as a preamp buss bar. I've also taken to putting the preamp filters on the board next to the appropriate stages, like Valve Wizard recommends. My preamp buss is grounded on the chassis floor with a bolt, and I no...

The lead dress in these Fenders is really bad. If you shorten the leads going from the board to all the preamp tubes, you'll probably take between 1 and 2 feet of wire out of the amp. The boost circuit injects signal from the reverb transformer output back into the signal flow. Thus, even if the boo...

Last night I got the tremolo completely squared away by restoring the connections to normal. I cured the ticking by gathering up all the leads to the trem tube and moving them away from V4. I zip tied them up to the filament leads. Now the tremolo works and sounds great. Folks like Gerald Weber who ...

I agree. In the few amps that used bias-vary trem, the intensity pot lead was the source of the bias voltage. I'm going to restore the thing to normal tonight. With so many years/owners in them, you just never know what you're going to find in an old Fender like this. For example, the trem wasn't af...

A client brought in a late 70s (pull boost) DR that he got cheap because it sounded horrible. It had been hot rodded in a really bad way, after someone else, presumably years before, had blackfaced it. Anyway, the tremolo circuit had been oddly modified at some point. If you look at the picture, you...

You may be way ahead of me on this, but in case you're not, you might want to make a couple of these gadgets to inject and/or tap a signal from different internal points on the amp. 1/4 plug & shielded cable (sacrifice an old instrument cable) at one end. On the other end, solder an insulated clip l...

It had whatever the stock Bassman 100 PT is. I can't check on it now, because the amp is at a studio as a loaner until I make the same amp out of a Bantam Bass 50 that the studio has. I was hoping to sell my amp when I took it to them. I had no idea he had two Bantam Bass chassis on a shelf. One of ...

If the tremolo is weak or doesn't work, here's my troubleshooting plan: 1. Swap out the tremolo tube for a known good 12AX7 with good gain. 2. If weak, put fresh bypass cap on the cathode of the first oscillator triode. If not working at all, replace the three caps in the oscillator circuit. They ar...

While I will stipulate that Gerald Weber holds on tight to some odd notions, his books are work getting, particularly for reference material for Fenders. The Valve Wizard site is great: http://www.valvewizard.co.uk/ I would also check out the The Ultimate Tone books, though they can be pricey. The o...

Would a 1N4937 do the job? I can get them from CEDist, but not the ones you mentioned.

Just for hoots, here are some pics of a 56 Harvard that came in for service. The only thing wrong with it was a completely trashed speaker.

Through my early 70s Greenback, the thing kills! Even though original, the caps still have a strong reservoir. Great amp.

I use the velcro strips on instrument cables. Under the board I wanted to get things up and out of the way so they are less likely to get hung up on something. As for the verbs, yep, i dig it. I had the Blue Sky first, then succumbed to Strymon's siren song after I got the Timeline & Mobius. The Blu...

I work on a lot of old (50s & 60s) amps. It's amazing how well some of those old filters still work. I've got a 59/60 tweed Harvard that has a really strong filter set--all original, and no leaky signal caps. My rules are: 1. Filters: Replace if failed, hummy or leaking goop 2. Signal caps: clean po...

OK, so maybe I'm the last guy on earth to think of this trick, but in case I'm not, I figured I'd share it. I use the big PedalTrain board. The square section tubes make sort of a grid like arrangement. I had the idea of putting velcro on the sides of the tubes so that I can use small lengths of vel...

I use the 100k RN65 resistors almost all the time on plates in builds and repairs. They are certainly quieter than old CC resistors. Both the RN65 and PRP are great for amps. I have a studio client who will get an amp and bring it to me to make quieter. My check list is basically: 1. Shorten grid le...