Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: jjschessmaster on August 08, 2026, 03:49:41 pm
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https://el34world.com/charts/Schematics/files/Carvin/Carvin_xseries.pdf
Hello! I made some mods to a Carvin X100 combo per this post. https://www.rig-talk.com/forum/threads/carvin-x100b-head-mods.123615/
I ended up doing a switch for removing bypass cathode capacitors on C2 and C36 (first and third gain stages). It makes a lovely clean sound when the drive is low but the output is low. Is there a way to increase the lead output? I have a spare slot on my on-off-on switch that works the C2 to lift cap and two different values. Wonder if I can use that at all to let more signal through in the off position.
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R94 and R34 seem to be parts of attenuators before and after the master volume. Try bypassing or adding a 47K-220K resistor in parallel with either one or both of them, this should increase the overall signal.
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Thanks for the input! I pulled the chassis today to take a stab at it and tried just a 220k and straight jumper over r34. The 220k was subtle and the jumper was more the boost I was looking for. With the jumper with the master at zero made a loud humming? I would have thought with r72 there it would still be ok? Any idea what's going on? Is it because one side of q2 is grounded? I put a 2k2 in there and it reduced some noise but still present. Just trying to learn what's going on in this stage of the circuit.