Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: DummyLoad on May 03, 2012, 01:40:04 am
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customer gave me a water damaged magnavox console - not pretty on the bottom - looks like it got wet and the veneer and plywood are separating. 12" speaker was rotted and the tweeter was fried - the cone is seized.
not much there to begin with, a mono ditch-digger with about 8-10W output with 2 cathode-biased 6V6GT in push-pull, 12AX7 paraphase inverter and single 6AV6 pre-amp stage. plugging a guitar into it after bypassing input EQ network was not WOW, just ho-hum, adding a 10uF cathode bypass to what is now V2 helped but still not WOW...
needed another gain stage: i gutted the phono connector and added another 7pin socket in it's hole for another 6AV6 gain stage and that became the first gain stage. hacked out the EQ network and moved the volume pot between V1 and V2. now we have a fairly fender-ish front-end with a funky tone-stack. some may recognize the james treble, but the bass is odd. i traced the circuit several times to be sure, and i believe the tone-stack is presented proper in the schematic.
replaced the 12" with a jensen 12". i scrapped the tweeter and cross-over network.
damn thing rocks!! separating veneer and plywood is buzzing a bit so need to spend some time with elmer and his clamp buddies.
--DL
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DL, thanks. Always fun to read about your projects.
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> recognize the james treble
I think you have the labels switched. The "Treble" gives fixed mid-hi loss and adjustable Bass loss. The "Bass" gives more or less treble-cut.
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> recognize the james treble
I think you have the labels switched. The "Treble" gives fixed mid-hi loss and adjustable Bass loss. The "Bass" gives more or less treble-cut.
they are. too much wine. ;)