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Hoffman Amps Forum image Author Topic: Help with Stomberg C AU 34  (Read 3294 times)

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Offline Gvkinney2002

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Help with Stomberg C AU 34
« on: September 27, 2019, 07:25:31 am »
Want to reddtore/modify a SC au 34 for harmonica.  Any suggestions ...?

Offline EL34

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Re: Help with Stomberg C AU 34
« Reply #1 on: September 27, 2019, 07:31:20 am »
This was posted in the wrong board
Moving it

Offline Tony Bones

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Re: Help with Stomberg C AU 34
« Reply #2 on: September 28, 2019, 05:24:52 pm »
Want to reddtore/modify a SC au 34 for harmonica.  Any suggestions ...?

Start by finding a schematic and posting it (or a link to it) here.

Offline PRR

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Re: Help with Stomberg C AU 34
« Reply #3 on: September 28, 2019, 07:12:16 pm »
Catalog blurb.

Offline sluckey

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Re: Help with Stomberg C AU 34
« Reply #4 on: September 28, 2019, 08:37:16 pm »
Lots of info on the net, including schematics. Cheap Sam's Photofact info. Take a look. Fix your spell checker though!  :icon_biggrin:
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline DummyLoad

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Re: Help with Stomberg C AU 34
« Reply #5 on: September 28, 2019, 09:55:48 pm »
.




Offline DummyLoad

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Re: Help with Stomberg C AU 34
« Reply #6 on: September 28, 2019, 10:35:03 pm »
.

Offline PRR

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Re: Help with Stomberg C AU 34
« Reply #7 on: September 29, 2019, 11:28:34 am »
I think it is a fine guitar-amp as-is. 6SJ7 is an excellent audio tube. 6SF7 is direct ancestor of 12AX7. Of course 6L6 is king. 6SN7 is no slouch.

DL's mods make sense. I'm looking at R23 C13. The intent is to "tame" the output stage, but there's a mild bass-boost in here. Short C13. Try a larger R23 until it gets some growl. This will also interact strongly with speaker bass resonance, so you want to try various speakers.

Hmmm... drawing shows 6SN7 but voltage chart shows 6N7. These are moderately similar but not identical, and very different pinout and should have different ratio at R20 R17.

I say fix what's broke and then fiddle a few connections and values. It's not begging for a rip-out.

 


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