V4 addition of adjustable bias pot

[danb435]

Thanks Liquids, very good information. I was a bit confused about the 75K bias resistor, then looked at the early 70's schematic and sure enough there it was. My V4 however is the '76 Magnavox era distortion version, which appears to be a different animal. That said, I still get the gist of the point you were making and it does make a lot of sense, taking into account all of the heat, possible vibration and banging around, that fixed resistors are a wiser and more robust choice. Regarding metal film resistors for bias, are these better because they are more stable under higher temps, quieter than carbon film, or what? I'm sure the blue color has some mythical properties that create a supernal cosmic effect on Halloween, but I'm not sure that's enough to special order them just because...
Thanks again for your sharing your wisdom.