Whistling sound from hardware reverb

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Whistling sound from hardware reverb

Post by wearashirt »

Hi guys,

What does a whistling sound from a hardware reverb mean? I saw in some forum that his hardware compressor (on the other hand) has whistling. So I thought it may have a common culprit.

I was recently handed an old hardware reverb (A.R.T.). The most of the finish has peeled off, but the board inside looks A-okay. It has a custom PSU and new BR2325 battery.

However, there's a whistling sound when the output is turned up. My workaround is is to max the input and minimize the output, and the overall gain is able to hover way above the whistling sound. Also, my mix console is able to phase-out hums and hisses. I can hear it audibly when I hit PFL on the effects return channel.

Any clues would be great, so I can bring it to the repair shop!
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Re: Whistling sound from hardware reverb

Post by Wonks »

If you can record some of the noise and upload to say Soundcloud and give us a link, that would help.

It could well be a ground loop issue, which taking it to be repaired won't solve. But without an example of the sound, it's very hard to say.
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Re: Whistling sound from hardware reverb

Post by Hugh Robjohns »

wearashirt wrote:However, there's a whistling sound when the output is turned up.


The usual cause for a whistling sound is some form of oscillation. Either the output is getting back into the input through inappropriate signal routing (either external to the unit, or internal) -- known as a howl round -- or the electronics have become unstable due to a fault and are self-oscillating
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Re: Whistling sound from hardware reverb

Post by James Perrett »

It may be worth saying that old budget hardware reverbs were never known for being quiet though they were normally hissy rather than whistling.
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Re: Whistling sound from hardware reverb

Post by Arpangel »

Check that you haven’t inadvertently turned up any aux sends on the effects return channel, especially the one that your reverb is on, as Hugh said, outputs back to inputs, can cause oscillations, check your routing.
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