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08-05-2025, 09:52 PM
Hello Mr. Makinrose
Since your concern is primarily regarding the reverb driver tube, might I suggest we look just at that?
The original Reverb unit with the 6W6 or 6V6 uses a 1k-ohm for bias, with +24V indicated on the schematic. Simple Ohm's Law says there is 24mA through the tube.
On the later reverb circuits using a 12AT7 with its triodes wired in parallel, has 2,200-ohms for bias and shows just +8.4V. This works out to 3.8mA which is one-sixth of the 6V6 current.
Overall, I do not believe that the difference of approximately 18mA will be significant to neither the load on the power transformer nor to the overall output power or perceived loudness of the amp based on the notion that both the Super Reverb and Bandmaster Reverb are 40W amplifiers.
We have no way of knowing what the actual specifications are for the original Fender transformers - at least for the power transformers - but we can make educated guesses.
My guess is that you have nothing to worry about.
Oh, you mention the OT as being 6k6. At 80W peak output 220mA is needed, which on a DC-basis would be 155mA.
Cheerio
Since your concern is primarily regarding the reverb driver tube, might I suggest we look just at that?
The original Reverb unit with the 6W6 or 6V6 uses a 1k-ohm for bias, with +24V indicated on the schematic. Simple Ohm's Law says there is 24mA through the tube.
On the later reverb circuits using a 12AT7 with its triodes wired in parallel, has 2,200-ohms for bias and shows just +8.4V. This works out to 3.8mA which is one-sixth of the 6V6 current.
Overall, I do not believe that the difference of approximately 18mA will be significant to neither the load on the power transformer nor to the overall output power or perceived loudness of the amp based on the notion that both the Super Reverb and Bandmaster Reverb are 40W amplifiers.
We have no way of knowing what the actual specifications are for the original Fender transformers - at least for the power transformers - but we can make educated guesses.
My guess is that you have nothing to worry about.
Oh, you mention the OT as being 6k6. At 80W peak output 220mA is needed, which on a DC-basis would be 155mA.
Cheerio
