block diagram

Issues continue, with the v-mid circuit and also with the fx loop.  Seems like stuff is breaking, right and left!  It had seemed originally that the fx loop was working properly, after I straightened out some circuit errors.  But I hadn't actually tested it comprehensively, beyond setting the gain level to be near unity.  Just now, when I was trying to use it as part of the regime for testing the new v-mid circuit, it malfunctioned badly.  When volume was up near max, it broke into obnoxious squealing.  Was it doing that before, and I just hadn't tested it?  Or is this due to the chassis being out of the box, with a bunch of test wires going every which way?  I need to track down the problem, obviously.  I'm not certain that I actually have the chassis securely tied to ground, so that'll be one thing to examine early on.

But anyway.  I've been feeling increasingly hampered by not having an oscilloscope, for this kind of debugging.  My old analogue scope is in San Diego.  I've tried to use "headless" PC scopes, but the cheap one I ordered a while back was non-working junk and I returned it.  So now, I finally bit the bullet and ordered a cheap Chinese standalone digital scope, with built-in LCD display.  Claims to be 100MHz and 400V, so that should serve my needs just fine if it actually works.

While I wait for this to arrive, basically at a standstill as regards progress, I took the opportunity to code up a nice PostScript block diagram of the amp, for inclusion with the owner's manual: