Built a Diamond Drive and a Plexi Plus and put them into a 1590BB for a dual British amp-in-a-box pedal.
I had very high hopes, and the Plexi Plus lived up to them, the Vox sounds fantastic, but I’m a tad disappointed that the Diamond Drive can’t be dialed back much at all. It DOES sound like a cranked Vox, but it’s like it’s on 9.7 on the gain when all the way down, and 10 when cranked. I want to check out the schematic and see where I can change a couple of components to give some “less gain” while retaining the ability to get the “more gain” stuff, too.
That said, the tones from both of these circuits are fantastic and definitely sounds like the two amps they’re designed to emulate. The Plexi uses the SMD J201s from the shop here, and they were pretty easy to set up with legs and socket.
Also, I set the bias as described in the build docs, then tried to tweak by ear, and it goes into cutoff before it cleans up very much, so that was my first thought as well. I need to double check my resistor values, but I think I got them all correct. Also, I used the “standard” value for the pots, not the one recommended for “more distortion”.