Allen ADC reverb issues

[julianjsoh]

Hi everyone,

The built-in reverb in our church's ADC5300 has begun being a bit cranky. Every now and then, when the reverb tab is engaged, a strange noise that sounds like microphone feedback that has a lot of echo to it at the tail end sounds. It sounds like the reverberated (tail end) of the organ's sound when the reverb is working normally, just that this noise is occurring above the actual sound of the organ. The organ still sounds, but with this strange noise going on above it. Once the reverb tab is turned off, it goes away at once. Is the reverb unit about to die? Any thoughts on a fix?

The second thing is that on this organ, the reverb tab does not stay on when changing between pistons. So I have to program the reverb stop into each piston's registration, otherwise it gets cancelled. Is this normal behaviour?

Thanks,
Julian

[jbird604]

Not sure what's going on with the noises in the reverb. I'd start with a very thorough cleanup of all the cables and connectors associated with the ADR, including the power cables that feed it. Also, the various mini-pots you can see through the holes in the face plate. In other words, extreme version of the routine maintenance that I always recommend on ADC organs.

As to the capture issue, normally the Reverb tab is set to "not on capture" and it doesn't respond in any way to the combination action. You can stop it from responding by removing the red push-on wiring connector on the back of the tab. This will remove the magnet-driving voltage from the tab, and thus it will not be able to go up or down except as you set it manually. So you can leave it on all the time if you wish and the cancel won't cancel it, nor will any other piston.

(I "think" the push-on connector is red. Anyway, it's the larger of the connectors if there are two, the one that has the fairly thick wires on it.)

[Hamman]

From a pure audio engineer standpoint, what you described as your ADC reverb issue sounds if though, somehow, wet (reverb output) signal is being fed right back into the input of the reverb unit....causing oscillation

[radagast]

Hi everyone,

The built-in reverb in our church's ADC5300 has begun being a bit cranky. Every now and then, when the reverb tab is engaged, a strange noise that sounds like microphone feedback that has a lot of echo to it at the tail end sounds. It sounds like the reverberated (tail end) of the organ's sound when the reverb is working normally, just that this noise is occurring above the actual sound of the organ. The organ still sounds, but with this strange noise going on above it. Once the reverb tab is turned off, it goes away at once. Is the reverb unit about to die? Any thoughts on a fix?

The second thing is that on this organ, the reverb tab does not stay on when changing between pistons. So I have to program the reverb stop into each piston's registration, otherwise it gets cancelled. Is this normal behaviour?

Thanks,
Julian

Is this digital reverb, or a mechanical spring type?

[AllenAnalog]

The standard reverb unit for the ADC-5300 was the ADR-4 electronic unit. It has an associated USRM mixer board. Both devices have switches and trimpots. As suggested by John, exercising the pots and switches (noting their original position before doing so) and cleaning all of the RCA cable connections to these two units might solve the problem unless there is an electronics failure or a switch failure with the reverb tab.

[Eric Mack]

As suggested by John, exercising the pots and switches (noting their original position before doing so) and cleaning all of the RCA cable connections to these two units might solve the problem unless there is an electronics failure or a switch failure with the reverb tab.

Do you recommend a DEOXIT type product be used on the pots and RCA connectors? They sell product for this purpose.