Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: jim on June 12, 2012, 09:53:31 pm
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I have a DR modified with the London Power pre-amp. I play out with it continually and it sounds great.
But now, I put these new hot pickups in my Les Paul for a more modern rock tone and the drive channel is now too bright, not actually brittle, but fat except with an icepick upper edge. I have tried all my most tired NOS 12AX7's and none of these warm it up. I can use my guitar tone control with success but I don't like doing it this way. The hemp cone Tone Tubby does not help this situation at all but I don't want to change it. I want to roll off the extreme upper edge of the drive channel. Not a big change. My DR, off course, has no mid control but the drive mids is a fixed 8K resistor. I would appreciate some help. Thanks, Jim
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This is not amp related but how close is your pickups adjusted to the strings. I would try changing pickup height to see if that helps. If you were happy with the amp before, your using the same guitar, it has to be the new pickups. Plate
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This is not amp related but how close is your pickups adjusted to the strings. I would try changing pickup height to see if that helps. If you were happy with the amp before, your using the same guitar, it has to be the new pickups. Plate
That may change the perceived "output" of his p'ups or the feel of the amp. It would def do the trick, though.
If you don't feel like digging into the circuit, you could always try a JJ ECC83 - will take the edge right off. But then again, you did throw up a schematic and probably have your iron all warmed up. :icon_biggrin:
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up the value of C9 and/or C11 as much as 1uf. You could also add a plate bypass cap to the 2nd or 3rd stage.
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I have already moved my bridge pickup away from the strings and it wasn't enough. But I just realized I could just change the tone cap on the bridge pickup maybe from .022 to .047 and I still get to use my iron. My amp drive channel can still use a little more thump and the next time I open it I will experiment with those cathode bypass caps. Thanks for the help. Jim
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Remove C11, then C9.
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These bypass mods are the ones I like to do and are very channel specific. One snip, listen, resolder or remove or adjust and move on. Easy. I'll try it. thanks, Jim
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I clipped C11 and not much happened but when I clipped C9 it mellowed perfectly. Suddenly the treble pot could swept a useful and reasonable range with any guitar. We all know how to adjust tone but to quantify the change.....Thank you, PRR. For fun I jumpered in a 1mf cap across position C9 and the tone was thumpy, scooped, and dark...for a short time I was Adam Jones of "TOOL." This design could be a jumping off point for metal mashers only adding a few mods and a cooler bias. I left C9 off because it sounded more warm and creamy without a bypass cap of any value and that is what I want. Jim
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> clipped C11 and not much happened
It's an ultra-high boost. If you want less icepick, you want to lose it. I suspected that was not enough; C9 is another high-boost.
10+uFd at C11 will bring up everything (bass through treble) if you need more gain. You probably don't.