FDP Forum / Twin Reverb crackling noise issues/ 7 messages in thread.

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kronrod



USA / San Jose

Dec 12th, 2016 01:38 AM        

Hello,<br /> <br /> I have a Twin Reverb amp and the issue I'm having is with loud crackling sound that it makes quite frequently. This is mostly with the Reverb turned on. <br /> <br /> This is not a consistent issue, and it can work for hours w/out issues and then it starts again.<br /> <br /> I had a local shop re-tube it an set bias, but still have not solved.<br /> <br /> Did anyone have issues like mine - what can this be?<br /> <br /> https://goo.gl/photos/QY68WhBV6WeSRTHh9<br /> https://goo.gl/photos/g5cS2AfYvUy6DNqAA<br /> <br /> Thank you!<br /> Kirill



Hammond101

Contributing Member
**********

So. Cal. USA

Dec 12th, 2016 09:41 AM        

Black face circuits sound this way when the grid/plate resistors begin to fail on the preamp tubes. I change the slope resistors also when I do these.<br /> <br /> Could be other things but check resistance with a DVOM. You can read these in circuit. If testing hot for DC voltage use caution and keep one hand in your pocket!<br /> <br /> I just copied your urls. It's a Twin Amp, not a Twin Reverb. The above still applies however with the channel switching and other goodies they have in this amp you could have a bad relay or switch causing this as well. Many more possibilities with the Twin Amp compared to the TR.



kronrod



USA / San Jose

Dec 15th, 2016 01:28 PM        

Great- thank you, Hammond101!<br /> <br /> Will try making these enhancements.<br /> <br /> Kirill



ABN



Spain

Jan 16th, 2017 05:48 AM        

Hello kronrod,<br /> <br /> Any update on this?<br /> I started to have the same issue on my Twin Amp.<br /> <br /> Thanks.



Steve Dallman

Contributing Member
**********

Merrill, Wisconsin

Age is just a number...mine is big
Jan 18th, 2017 06:28 AM        

I just chased such a crackling noise in my 65 Princeton Reverb. <br /> <br /> It was a broken ground on the brass strip, under the controls. This is common and I actually feel a little foolish not finding it sooner. 15 years ago, it would have been the first place I'd look.



ABN



Spain

Jan 23rd, 2017 03:13 PM        

Here is a video:<br /> https://youtu.be/uwI5NvADJoQ



pdf64



UK

Jan 24th, 2017 02:27 AM        

That's interesting - it seems as if the noise is being 'reverbed'.<br /> So the noisy circuit is likely in/prior to the driver stage, rather than the recovery stage.<br /> <br /> Can the noise be detected in the background with the reverb turned to minimum, eg with presence turned to max?<br /> Does switching the fx loop in/out affect the noise? Turn send and return level controls to max.<br /> Is the noise affected by which power mode the amp is set to?<br /> Does the noise stop if the amp is operated without a tube (12AT7) in V7?



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