peavey heritage vtx mods

OK, done (I think) with this reverb damper and the associated changes to the amp cabinet.   I made a video, demonstrating the operation of the damper mechanism, including the first audio test: I hooked the reverb output up to a stereo amp, and manually bumped the springs with my finger to create a reverb sound.  With damper off and damper on, there's a clear difference in tone and decay time: pretty much right along the lines of what I was hoping for -- at least as far as I can tell from this primitive test. https://youtu.be/n60kjWGzs7A

I was going to have the reverb damper control panel located two plywood layers deep, but this would have necessitated cutting a nicely-shaped oval hole in the original baffle to line up with the oval in the new baffle.  This would have been difficult since the old baffle is not removeable, so given the protruding edges of the cabinet sides, it wouldn't be possible to get my power jigsaw in there to do the cut.  I would've had to use some kind of small hand scroll saw, which I don't have so first I'd have to go tool shopping...  And anyway, I didn't really like the knob being that far back inside a "tunnel" of plywood layers.  So I realized, I could just cut out a larger square-side notch in the old baffle, as seen, and then mount the panel at the level of the back of the new baffle, so going through an oval hole in only one layer of plywood.  Looks better, and easier to implement. As you can see here, the reverb base mounts with the control panel protrudin...

In order to facilitate installing this new reverb damper mechanism, I will mount the reverb tank on a plywood base.  (This will cause the tank to protrude higher into the space behind the speaker; I hope it doesn't interfere with the speaker, I haven't carefully tested this!  If it doesn't all fit properly, I'll just have to start making changes...)   ...As you can see, I've used a cannibalized 6mm pot body for the control shaft, so that I can attach the same type of knob that the rest of the control panel will have.  I'll cut a hole in the speaker baffle to expose this reverb damper panel.  With my usual laser-printed label and epoxy finish, it should look pretty decent! The knob travels through about 180 degrees; ccw is damper-off,  cw is damper-on.  The bent wire rises up and contacts the springs, when the reverb tank is in place.  The wire will be covered with felt -- at least, that's what I'll try first.

When I tested the spring reverb, back in San Diego, it was roughly functional, but performance was terrible.  When turned up at all, it would start to go into acoustic feedback.  It was necessary to keep it pretty low, to get any usable reverb sound at all.  This is not what I want; if I'm using reverb, I want an overwhelming wash of wet sound!  If I'm going for a subtle edge of reverb, then in live situations, I'll just as well turn it all the way off for a tighter sound.  In recordings, of course I'll be using digital reverb in the mix.  I'm no special fan of spring reverb, I hate the "twangy" or "drippy" sound, I'm no surf-rocker or rockabilly player.  I use spring reverb if it's all that is available, and the more it sounds like plate reverb, the more I like it.  But if I'm using it at all, then I want a lot of it. Since it's obvious that less-than-careful people have been inside this amp before me, and the reverb tank had cle...

  The parts listed under "cathode bias" are to be soldered to the VTX power tube board.  Everything else mounts within the extension chassis.  Most components mount on two circuit boards, as seen in my drawings; a few components mount directly to the back of pots. The stars next to some component values are my non-specific indication that these components should be "up-rated". For capacitors, the voltage rating should be higher than the +HV rail of the circuit in question.  In this amp, with its relatively high +525V rail, the starred capacitors should have voltage ratings of 630V or higher.  Unmarked capacitors should generally be rated at 50V. For resistors, the star means that the wattage rating should be higher.  Unless marked otherwise, in this amp, I am using 2W for starred resistors.  Unmarked resistors are 1/4W.  The up-rated resistors should be mounted a few mm above the board, and similarly separated from any other components, for proper...

  (Updated drawings, minor corrections.) (More corrections:  Electrolytics are 22uF @ 50V, not 25uF.  Decoupling caps are 22nF @ 630V, not 20nF.  In cathode circuit of phase inverter, it's a 5.6k resistor, not 5.8k.  Also, note that in my actual layout of the two circuit boards, I have placed all of the HV power supply components (2 x 10uF electrolytics and 2 x 10k @ 2W resistors) in one group at the right end of board #1.  Finally, there is an additional 100k LED resistor next to the two shown, on the left end of board #1, and there is a 10M LED resistor next to the HV supply components on the right end of board #1.  These are for the RGB pilot LED (red = +15V, blue = HV).) (Still more corrections:  The two 220k resistors associated with the phase inverter, need to be grounded at the node where they connect together.  And the two 0.1uF caps connected to these resistors need to be rated for high voltage (630V being my standard throughout the ...