Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: mresistor on December 20, 2017, 12:15:50 pm
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I've looked in the Schematics section and cannot find a 6G7 schematic or layout for a Brownface Bandmaster with 6 preamp tubes. Yet when I search the internet I can find pictures of the amp in question.
If there were two variations of the 6G7 where is the schematic for the one with 6 small bottles? What was the extra bottle used for and how was it incorporated into the circuit?
Only thing I can figure is it is like a 6G8 Twin with only 2 power tubes and it has an extra amplification node off the vibrato. Looking at that circuit the vibrato portion is really funky.
Does anyone know the history of this Bandmaster and why there is not a separate designation for the two different circuits.
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Interesting - wasn't aware of any 6-pretube browns that didn't have the 'A' designation (unless is an early 'A' model that has a transitional tube chart or something?)
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6G7 has a two tube vibrato circuit and only requires five little tubes. 6G7A has a three tube vibrato circuit and requires six little tubes. Both schematic/layout files are in Hoffman's schematic library.
If you see a 6G7 with six little tubes it's probably really an early 6G7A and Fender just slapped an old tube chart on it, either intentionally or accidentally. Fender did stuff like that quite a bit.
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Aha thank you I see it now.
It would be logical that the 6G7 came first. However that doesn't seem to be the case.