I originally done the Pentode / Triode mod and while it reduces the power down to 3 Watts, that's still too loud for evening bedroom use. Normally, the Pentode mod would warm the sound a little, but the Marshall mod already gives it warmth anyway, so that mod was there just for the sake of it.
I wanted a power reduction method that was simple effective, cheap and one click. So I made a resistor network in place of a master volume. This allows a massive drop in output power while giving full gain. So at midnight when the kids are in bed, you can have those Hendrix /Page tones at a few hundred mill-watts
In conjunction with the two gain stages, you can up that to evening use and TV use ( three different quiet volume levels on full chat )
Not quite. It dumps signal to ground prior to the EL84. It's different on the Epi because there is no tonestack. The GA5 has the Marshall tonestack, plus it can be switched in & out, so R15 and R5 values are not the same and are changed according to the mode.
On the Epi you can sling a 500k pot in place of R5 and put the wiper on R15 for a crude(ish ) MV control.
I don't understand how you then get the full EL84 drive if you reduce the signal going in?
Surely that's just a master volume and not an attenuator?