proper reverb tank installation

[scole]

im building a princeton reverb, im wondering how to install the rev tamk, does need a bag? should it have a cover on the bottom?

[Enzo]

First, there is a drive end and a pickup end. The pickup end is marked OUTPUT. That end should be mounted as far from the power transofrmer as possible.

The whole point of covering the bottom and bagging the pan is to reduce the acoustic feedback potential. The sound from teh speaker can vibrate the springs, which in turn are fed back into the amp. It is possible the pan can then feed back. It will be a low note.

A cardboard cover over the bottom of the pan helps, and then bagging it helps more.

Even when not covered, there are considerations on mounting.

They usually come with soft squishy grommets in the mounting holes..Screws through those holes should never be cranked down tight. The vibration in the cab would then be transmitted to the frame of the reverb pan. The screws should be turned in only enough to stay put. The pan should float on the grommets.

Another trick is to take a strip of adhesive backed weather stripping or other rubber strip and stick a length of it running down the top of the pan. This prevents the wide area of sheet metal that is the pan top from vibrating. CAr makers do this inside large body panels on cars to reduce "sheet metal" noise.

[tubeswell]

FWIW I am interested in this topic at the mo' (cos I too am working on a project involving reverb) and I came across this on google - courtesy of someone who has built a stand-alone reverb thingy. I thought it was interesting. I'm not sure whether this way of mounting the pan it would make the pan more prone to external bumps and vibrations tho'.

I see from looking at the Fender '63 (re-issue) Reverb Manual (also attached) that the pan in these was similarly mounted (see page 6 - under the items spring anchors and spring extensions). I wonder if this method adds to the boingyness? ;-)

Having said that, Enzo's idea of door rubber weather seal strips sounds alot simpler.

[Enzo]

The Fender tube reverb mounts the pan in mid-air hangong from four strong springs. it works but would be a pain to duplicate in my mind.

The rubber weatherstrip I used is not for mounting, though one could use strips of foam as mounting cushions instead of grommets. What I refer to is the wide flat top surface of the pan. it can resonate acoustically. Sticking a long stripe of rubber or foam stripping down the centerline of it will dampen such vibration.

There is no speaker in the stand alone reverb, so many of the acoustic considerations are moot. As to boingyness, I would hope we were not moving the unit around while we were playing.

The whole thing boils down to keeping the vibration from the speaker and cab from conducting into the spring unit.

[txstrat]

Would the vibration of the speaker(s) interfere so much?
I mean, when you play and have the reverb on and the speakers vibrate so much that it interferes in the tank, I would assume the loudness of the amp would be so high you wouldn't notice the interference. Cause the signal of the reverb gets higher too with the loudness.
Just a thought.
I built two amps so far with a reverb and fixed the tank on the bottom. I have not noticed any problems yet, but I haven't thought about it either. Maybe I should listen closer. What would the difference be like?

Matt

[scole]

i was thinking of a false bottom using 1/4 ply to hide the can in the bottom of the amp. also keeping the springs free of dust is probably very important as well.

[txstrat]

Keeping the dust away is a good idea.
I might would reconsider the double bottom thing. Cause you'd always have to remove it if anything goes wrong. I screwed the tank down to the bottom, cut a piece of my tolex to the right size for the tank and covered it srewing the tolex down with 4 short screws.
You barely notice the tank when looking inside the amps back.

[Enzo]

The speakers don't interfere with the pan so much, it is just that the pan can pick up the speaker vibration like a microphone to some extent. It is not always a problem, of course. I don't think putting it is a sealed chamber is necessary, the traditional bag works well enough. And in many cases, the reverb is fine just exposed.

Set the pan in the bottom all by itself and play the amp. if the reverb doesn;'t feed back at higher settings , then it is fine as is. If you turn the amp up to stage levels and crank the reverb up, and you start to get this woooooo building up, then the pan is feeding back, and you deal with it.