Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Carlsoti on June 11, 2024, 09:51:56 am
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I recently found an old Qual-Kit 2200 HiFi chassis hiding under my sofa. It's got 2ea 12AX7s, 2ea 6V6s, 1ea octal rectifier spot. Originally, I think I was shooting for a no B.S. 6G2 copy, but now I'm thinking of using a SS trem osc and repurposing that triode for switchable additional gain.
There are a few other mods I'd like to add, as well, including adjustable bias, a pre-PI MV(Will be needed with another triode out front), a 3-way NFB/NO-NFB/No-NFB+ cathode bypass switch, and moving the tone control to something more like the Vox cut control. My strat has PTB, so I feel that the late-stage tone-cut will work better for me.
Is there a variation of the TON that will allow it to work more-or-less as the stock trem circuit does in addition to an adjustable bias, or am I getting too greedy?
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Is there a variation of the TON that will allow it to work more-or-less as the stock trem circuit does in addition to an adjustable bias, or am I getting too greedy?
I've never seen such. The TON is not designed to operate as a bias vary tremolo like the 6G2. It's a shunt attenuator like the AB763 amps.
If you want the stock trem AND adjustable bias just copy Hoffman's Princeton Reverb circuit. It's just a simple mod to get adjustable bias..
https://el34world.com/Hoffman/files/Hoffman_PrincetonReverb.pdf
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I have just realized that I had gotten my wires crossed searching for answers. The TON is a tube based circuit that others have modified with a MOSFET in place of the triode. I'll have to do a bit more digging. Thank you, Steve.
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I started down the same path you are thinking about, SS 6G2 trem.
I got the actual MOSFET LFO to work well, but burned up a few of the MOSFET followers, trying to get the bias-vary type running.
Then I took a left turn & decided to try the MOSFET Trem-O-Nator, for which there was already a schematic. (attached below)
Had it working but other things came up, so fooling with that got shelved for now.
I have several more SS trem schematics in the folder (I did not design them) if you want to check them out.
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These might also be of interest. 2Deaf did several of the schematics I have gathered.
Keep us posted if you get to fooling with these or find a good combination of circuits.
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This is what Hoffman's PR circuit would look like with a LND150 oscillator. Should work without any changes. :dontknow:
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This is what Hoffman's PR circuit would look like with a LND150 oscillator. Should work without any changes. :dontknow:
Cool, I will have to try that out when I get back to that project. Thanks!