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Agree, it must be the "good" one 
Voltages now make sense, specially around V1b.
I guess they wanted "just a little more gain" in the dirt channel but without using an extra valve, so they modded V1b gain stage into a "starved plate" design: as large a plate resistor as can be, accept huge voltage drop across it so low plate voltage, problem is that stage is anemic, dull, all for very little extra gain.
I suggest you turn *that* gain stage into a normal one: 100k plate, 1k5 cathode, bypassed with .47 or 1uF electrolytic.
Ditch the cathode diode of course.
In any case that channel is a fraud: being a gain block followed by clipping diodes (W005+1N4007) , it´s not more than a glorified distortion pedal.
Going any further would mean ripping entire sections, full rebuilds, way beyond the call of duty.
Try turning the starved plate stage into a regular one, it should improve sound, not sure about that channel "lower volume at the same setting" but it might improve that too.
I don´t suggest pulling the clipping diodes, because switching here is done by very weak transistors inside the chip, which is just a transistor array, faintly remember they stand 20V or so.
Clipping diodes keep peaks at 2.1V ; without them you could easily have 30 or 40V RMS, not good.
Ok, try it and post results.
Good luck.
Voltages now make sense, specially around V1b.
I guess they wanted "just a little more gain" in the dirt channel but without using an extra valve, so they modded V1b gain stage into a "starved plate" design: as large a plate resistor as can be, accept huge voltage drop across it so low plate voltage, problem is that stage is anemic, dull, all for very little extra gain.
I suggest you turn *that* gain stage into a normal one: 100k plate, 1k5 cathode, bypassed with .47 or 1uF electrolytic.
Ditch the cathode diode of course.
In any case that channel is a fraud: being a gain block followed by clipping diodes (W005+1N4007) , it´s not more than a glorified distortion pedal.
Going any further would mean ripping entire sections, full rebuilds, way beyond the call of duty.
Try turning the starved plate stage into a regular one, it should improve sound, not sure about that channel "lower volume at the same setting" but it might improve that too.
I don´t suggest pulling the clipping diodes, because switching here is done by very weak transistors inside the chip, which is just a transistor array, faintly remember they stand 20V or so.
Clipping diodes keep peaks at 2.1V ; without them you could easily have 30 or 40V RMS, not good.
Ok, try it and post results.
Good luck.
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