first look at the internals

 

Opened the unit up, to survey work to be done.  While in there, I took the opportunity to unplug the "ground polarity" switch (aka death-cap switch).  Amazing that they still had those, in what I'd estimate to be the early 1980s.

The way the speaker baffle is made, it's glued into routed slots, so I think it would be difficult to fully remove (to convert to a 1x12).  So instead, I'll cut most of it away, leaving a lip around the edge, and then attach a second layer of plywood onto that lip.  The speaker will be inset rather than top-mounted as they are now, and I suppose I'll use my usual sandwiched metal grate speaker grille instead of the Peavey plastic-fabric grille.  The current velcro-on grille frame has been rebuilt by somebody, rather inexpertly.  That's part of why there's no Peavey logo.

I'm still not sure if I should call this "Heavey", or "Peavish".  It's so damn heavy that it peeves me, so could go with either...

Looking at the schematic, BTW, there is no way to combine reverb and phaser control into one (SPST) footswitch, except by adding a relay or other complication.  So, I'll just keep the footswitch as-is (after my mods), controlling the channel switching and reverb, not the phaser.

One other mod I think I will make, when I get this amp back to Seattle and begin working on it in earnest: I will separate the two input jacks, so that when both are used, one goes to the norm channel and the other goes to the lead channel.  So two instruments could be supported, such as guitar and bass or guitar and pipe organ.  Peavey should have made it this way in the first place.  The jacks are wired through a three-conductor cable to the PCB, so it seems like they were maybe planning to do this, and the "combined" channel mode further supports this; but then the layout of the PCB connects the jacks together like most Fender-style two-jack front ends.  When only one instrument is plugged in to either jack (high gain or low gain), the jacks will combine through the usual jack-switching path, so that either or both channels can be used.

It's a lot of small changes and mods to make, when honestly I'll probably seldom use the solid-state VTX preamp anyway, once I have my AB763 tube preamp available, but I want everything to be corrected and optimized on this amp, as it will become my primary live performance amp in the near future, if all goes well.