At some point in 2020/21, I must have thought that it would be a great idea to build a high-gain amp without a master volume, or perhaps make it more versatile with a simple two-wire post phase inverter volume control. Turns out I was very wrong.

I wired everything up for a first test, and it immediately became clear that I can’t test this amp at home. It is ferociously loud – ridiculously, absolutely scary. On the plus side, the layout itself seems to be working. From what I can tell, it has little to no hum, and the noise is probably low too. However, without the master volume, it sounds like my vacuum cleaner…

Anyhow, here’s a glamour shot of the cable lacing:

The two-wire master volume still gives me too much output to reasonably test this amp in my apartment, so I experimented with some quick master volume hacks, but to no avail. Maybe at some point, I’ll test other PPIMV variants, but right now I don’t have any dual gang 250kA pots lying around, and it somehow feels wrong to go that route (it would also make the faceplate labeling look silly). So the next step will be making an attenuator (a quick Google search led me to J. Hewitt’s M2 attenuator, parts are ordered) to hopefully be able to test and tweak this monster of an amp.