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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Wow! Great! You could avoid remounting in a separate enclosure... that looks so cool!
The first thing in pa-guitar amp job is to check if the pa works as it was intended to work. First repair the pa then convert it to guitar amp. Sorry, no schematics. Could you tell us what tubes are inside?
The first thing in pa-guitar amp job is to check if the pa works as it was intended to work. First repair the pa then convert it to guitar amp. Sorry, no schematics. Could you tell us what tubes are inside?
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.
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.
majorarmspeed said:5U4, 6L6, 6L6, 6N7, 6J5, 6SJ7, 6SJ7.
YOU ARE A LUKY MAN! those tubes are very useful in a guitar amp... especially the 6L6 outputs...
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...
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...
Take a look at the Stromberg AU32 and AU33 schematics on my web page - this on is similar, though it doesn't quite match either one...
My Stromberg page
My Stromberg page
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