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A friend has just bought a hand wired/made boutique amp(expensive)and the reverb does not work, he phoned thinking it was because of the securing screws, and the builder told him the tank should not be screwed tight to the cabinet (4 screws) as it causes problems, there are only 2 diagonally in his and not tight. members views please

If the reverb tank has got holes at the four corners for mounting screws (which is normal) then using only two sounds wrong. As Dave R. says, it should have rubber mounts (rubber grommets, in fact). In this way the screws are held firmly into the wood of the cabinet but the reverb is suspended on the rubber grommets, giving some immunity to cabinet vibration from the loudspeaker.

If the reverb isn't working, then the owner can do some simple faultfinding with the aid of a screwdriver. First, use the screwdriver to undo the mounting screws and turn the unit over. Now switch on the amp. This is quite safe - there are no dangerous voltages in a reverb unit.

Inside there will be a spring (or springs) connected to transducers at either end - one transducer twists the springs and makes them vibrate, the other picks up the vibrations. Turn up the amp's reverb control and tap the springs gently with the screwdriver . Do you hear the characteristic 'boing and clatter' of a shaken reverb spring? If you do, then there is a fault in the 'send' circuitry, or the 'send' transducer is faulty. If you don't (or the sound is very, very faint), then the pickup transducer or its circuit is faulty.

Either way, the owner has every right to go back to the builder and ask to have it fixed (and to have the reverb mounted with four screws, all with rubber grommets).

Ray

The reverb tank should at the very least be mounted with screws passing through rubber grommets in the tank and in my opinion 4 screws would not be a problem. Alternatively these mounts provide a decent degree of isolation from cabinet borne vibration: - http://www.maplin.co.uk/anti-vibration- ... unts-43552

The wires that go internally from the RCA/phono sockets on the tank to the transducers sometimes come adrift and the delicate fine wires of the actual transducer coil can easily be broken in which case a replacement reverb tank would be needed (quite easily available eg from Allparts).

But as Ray says, with a newly built amp, it should be working

Thanks to all, will pass on views/advice, builder sending new tank

I had to buy a new one from' Acoustitronics'

Accutronics - You can get them on Ebay but Allparts have quite keen pricing

http://www.allparts.uk.com/online-shop/ ... 5_495.html

The earliest spring reverbs were, I believe, fitted in Hammond organs to give a 'big hall' sound to what was being sold as a parlour instrument. Would it have been Leo, that great innovator, who first put a Hammond spring in a guitar amplifier?

The Hammond spring became the basis of the Accutronics company.

In the mid-fifties, Joe Meek made his own spring reverb using an electric fire element, then wrapped the whole box in layers of tape so no-one could steal his 'secret'. Nowadays, he could have his choice of 15 models for a modest sum!

Ray

RogerCook wrote:

I had to buy a new one from' Acoustitronics'

Accutronics - You can get them on Ebay but Allparts have quite keen pricing

http://www.allparts.uk.com/online-shop/ ... 5_495.html

Anyone wanting a reverb tank buy a MOD from amplified parts USA £20 inc p/p to UK, much better/cheaper than a Accutronics

Hi,

I have several of the Hammond units here - they are "The Mutts Nuts"

But are valve driven, and recovered..

I seem to remember that Fender were the first amps to feature "Hammond Reverb"


It took quite a few years for other makers to clone these tanks, the most famous one being Accutronics.

Actually the reverb spring unit is mounted on 4 springs anyway so even bolting the outer carrier direct to the cab
should not cause problems..

The earlier reverb unit used by Hammond was this one:-



Used in Hammond PR20 and 40 tone cabinets, the 3 springs give a full rich reverb, but if the cab is knocked they make a hell of a noise...

The PR40 is a 3 channel amp using 6 EL84's givin an overall power of 40 watts.