Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: zfiles1701 on July 11, 2011, 09:09:06 am
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Converted channel one into a plexi type channel (it bypasses the reverb/trem). Used one tube so no CF. Went from input gain stage, to vol, directly to tone stack, then to second gain stage, to the PI. That simple. Voltages checked good, installed tubes, voltage good with tubes, and did a sound check. Some high pitched squeel when cranked, but not that bad. Is it safe to put a 12ax7 in the PI instead of the 12at7 to get more gain? And, should I use the 220k/.01uf input to the PI that the other channel uses? (used a .047 cap with no resistor) What I am after is making a distortion channel in the AB763. Understand it will not be a plexi or marshall-just want something with more crunch and bass. Anyone else do something like this? Thanks
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Do Channel one into channel two. Plug into channel one for high gain... Plug into channel two for fender clean. Simple?!
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Use the bright switch as a tone stack lift.Then you get lots of gain.
Did you use 220k plate resistors?
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Used 100k plate resistors like stock marshall and fender. Took it for a test run cranked. Input tube was microphonic, swaped and that prob gone (squeel). Sounded pretty much where I wanted it to-much more crunch than fender channel and pretty hot anywhere from 4-10 on the volume with humbucker of course. But beyond 7, when not strumming got motor boating (more tweeking reqd). :help:
Did not want to just boost the fender channel because that channel cuts the bass too much. Reverb works better when not overwhelmed with too much lows (from what I have read here). So I used channel one bypassing reverb. Do not want to bypass the tone stack (few amps I built sound marshally when the plexi tone stack is there), wired it up to resistors instead of pots at full tilt except for the treble pot. (will try tone stack after 2nd gain stage too)
Basic and border line dumb question: Which channel on the hoffman stock plexi is the bass channel-I don't know which plexi channel I built (go ahead LOL). :help:
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Which channel on the hoffman stock plexi is the bass channel
Refer to the layout... V1A (pins 1,2,3) is the bass or dark channel.