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Post subject: 1972 Deluxe Reverb, "reverb"?
Posted: Wed Oct 06, 2010 5:33 pm
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Anybody have experience with the reverb section on a 1972 Silverface DR? I just picked one up and it sounds great, but the reverb seems to have an underlying decaying pulsing sound, especially when played at low volume. At medium stage volume you don't notice it as much, but when messing in the studio, it doesn't sound clean and smooth. The best way to describe it is reverb with a background decaying quick pulse, not really clicking but it reminds me of what might be called a reverb click.

I have a bunch of other amps with reverb and I work on vintage gear and have never encountered this issue. Just wondering if it is inherent in the SF DR circuit, or if I need to do some doctoring.

Thanks..


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Post subject: Re: 1972 Deluxe Reverb, "reverb"?
Posted: Wed Oct 06, 2010 7:05 pm
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BarN wrote:
Anybody have experience with the reverb section on a 1972 Silverface DR? I just picked one up and it sounds great, but the reverb seems to have an underlying decaying pulsing sound, especially when played at low volume. At medium stage volume you don't notice it as much, but when messing in the studio, it doesn't sound clean and smooth. The best way to describe it is reverb with a background decaying quick pulse, not really clicking but it reminds me of what might be called a reverb click.

I have a bunch of other amps with reverb and I work on vintage gear and have never encountered this issue. Just wondering if it is inherent in the SF DR circuit, or if I need to do some doctoring.

Thanks..


Have you tried replacing the reverb tube?


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Post subject:
Posted: Wed Oct 06, 2010 7:54 pm
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All tubes are new, I am wondering if I need to go through the reverb circuit and replace caps or resistors.


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Posted: Wed Oct 06, 2010 8:54 pm
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That's a new one on me, and I've been around these amps a while. Sounds like you've been around the block too. So this isn't a flat out oscillation, but you're losing the reverb effect in a pulsing fashion, right ? And you're losing the entire signal slowly only when the reverb section is engaged,right ? I guess you've already tried another tank. I'd go with a votage check to make sure the trans is OK, then on to the caps and resistors, like you said. Yeah, with the tank, trans, and tubes out of the equation, I'm going for a leaking coupling cap or a bum bias cap. Art

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Post subject:
Posted: Wed Oct 06, 2010 11:56 pm
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I usually change the bypass caps on the 12AT7 reverb input and 12AX7 recovery tube to 25 mfd/50 VDC. Coupling caps to 12AT7 and to "reverb" pot maybe leaky. Good luck!


http://www.ampwares.com/schematics/delu ... _ab763.pdf


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Post subject:
Posted: Thu Oct 07, 2010 5:50 am
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Thanks for the ideas. I haven't replaced the tank, but I dismantled and checked it out, ran it though another amp's reverb circuit and it checked out OK. I will focus on the caps and the voltages first.

Thanks


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