• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Stromberg-Carlson project

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I just picked up a Stromberg-Carlson Model 20 PA amp for conversion into a guitar amp. It' sfrom the forties; two huge white chickenhead knobs on the front. Where do I start? WHo has schematics? Will human sacrifice be necessary to get it running? Thanks.
 

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I do indeed have the amp; I bought it on FleaBay and it was delivered yesterday, but posting the auction pic was quick and easy.

And it's pretty rough. A cap can is physically disintegrating, the wires out of the octal connectors have been cut, and it looks like it's been sitting for about thirty years. That's the bad news. The good news is that there don't seem to be any major corrosion issues, the cloth covering on the wires is intact and not fragile, and the solder connections look solid. And, it looks cooler than anything I've owned in my 47 years.

More bad news: no schematic on the bottom cover, because there is no bottom cover.

Lots of work before it comes within ten feet of live electricity, but I'm psyched.
 
Well, 6N7 and 6J5 are just triodes. To me they look much similar to 12AU7 or 12AT7, just with increased ratings. 6SJ7 are small signal pentodes, they could be useful. Normally in a guitar amp you would use them as triodes, to stay away from microphonics and noise, other than blocking distortion. But if you have few gainstages I would use the pentode mode... people says that pentodes have interesting overdrive characteristics...

In any case you're luky! Here the only tube thing I could found is an old stereo hi-fi amp that's too well made to convert it to a guitar amp. It's a El84 pp... just rebuilding it...

Keep posting! Especially when you have photos and traced some thing of schematics...
 
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