about the spring reverb...

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 clearly been disturbed among other things, I might have thought that something was wrong with this particular unit, something which could be fixed.  However, looking online, I see a lot of people complaining that the reverb on these VTX amps tends to go into oscillation.  It may be a systemic issue.  So, I think I will try mounting the reverb tank inside some kind of muffling enclosure, like several layers of felt or cloth.

As long as I'm futzing around with the reverb tank, I also think I may try adding a "damper" control.  This is an idea I've wanted to try for a while, with spring reverbs.  If it works, I will probably incorporate it into my "McGrath Stereo" amp as well (with the twin reverb tanks).  The idea is, a knob on the front of the speaker baffle (down low in the corner) rotates a shaft which goes underneath the reverb tank.  When rotated, the shaft progressively brings some kind of damping material (like felt) into contact with the springs.  Somewhat analogous to the "buff stop" on a harpsichord.  It'll be a matter of experimentation to figure out what material to use, and where and how to bring it into contact with the springs.  I've seen people do this with plate reverbs, and I've seen people obtain interesting damped-decay effects with spring reverbs by manually pressing cloth against the springs, so having a knob to do this conveniently seems like it will probably be a useful capability.

(Later...)

Aha, turns out maybe there was something wrong with this reverb.  As I was examining it up close, pursuant to fitting this damper control, I found that one of the four corner springs which suspends the inner chassis inside the metal tank (box), was disconnected.  Probably due to ham-handed fiddling by previous humans: there isn't really a way these springs can disconnect on their own, without much other major damage being evident.  As a result of this, instead of "floating" in the middle of the tank, the chassis was held pinned against one of the guides by the asymmetrical force of the remaining three springs.  This meant that it was much more directly coupled to the outside tank than intended, which was almost certainly responsible for the excessive tendency to feedback.  So I hope to get much better reverb performance, once this amp is put back together.

(I wonder if this issue is behind the other reports of reverb feedback and oscillation.  Maybe Peavey had a batch of these Accutronics reverbs which were poorly assembled.  They're usually pretty good, but who knows, maybe Peavey got a deal on some rejects?  I'm still going with the inept human intervention after the fact theory, though.)