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Post subject: Crackling noises from reverb unit
Posted: Tue Jan 17, 2017 7:41 am
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Dear members, have a nice 2017!

Yesterday, while rehearsing with my band, suddenly, out of the blue, my Twin Amp (Protube series, from 2002) started making crackling noises. They were loud! I was playing with volume at 2, and the noise were equivalent in decibels to the sound of the guitar played at that time.

Soon I found out that if I turned reverb off, there were no more noise. The amp was hot, and I was in a hurry, so I couldn't wait until it cool off a bit and swap the reverb tubes.

I'm right now at rehearsing room. The amp seems fine, now.

The tubes have couple of months...and the RCA are in good condition.

Yesterday I turned off reverb at the footswitch. I presume if I turned it off at the knob it would go away the same way.

From my experience, reverb units have lots of problems. I'm more and more leaning towards the use of reverb pedals. Unfortunately :(

Can't find out the cause of the problem :(

Have you experienced similar situation before?

Thanks, and best regards.


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Post subject: Re: Crackling noises from reverb unit
Posted: Thu Jan 19, 2017 2:46 am
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2 post for same subject ?

What is you experience to say tubes are good and RCA are good ?

I never heard or see there are many trouble with reverb pan. Like anything , it could hapend.


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Post subject: Re: Crackling noises from reverb unit
Posted: Thu Jan 19, 2017 3:15 am
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Dear stratele52,

Two posts for two diffrent problems.
Crackling noise is one problem. Hum on the circuit is another problem.
It's all written on the posts.

Tubes have 6 months, are Groove Tubes tested and installed by my technician. Same for RCA connectors.
Crackling noise came out of the blue, and only with reverb on.


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Post subject: Re: Crackling noises from reverb unit
Posted: Thu Jan 19, 2017 4:54 am
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Yes 2 different problems, 'cause I read half of this post talk about reverb.

Crackling ;
Tubes.
Or Output tubes bias to hot.
Socket contacts, loose or dirty
bad solder or resistor in power supply


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Post subject: Re: Crackling noises from reverb unit
Posted: Thu Jan 19, 2017 1:42 pm
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I had what sounds like the same problem when I replaced the reverb driver tube in my DRRI. I replaced a perfectly good GT-12AT7 with what turned out to be a faulty NOS JAN Philips 12AT7WC! Supplier replaced faulty tube under warranty and there has been no recurrence of the problem.


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Post subject: Re: Crackling noises from reverb unit
Posted: Sat Jan 21, 2017 9:56 am
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The reverb muting is just beyond the pan. You could have bad pan wires, but under the circumstances, its more likely the reverb driver tube V7, overheated and crapped out.
I thought you said you changed all the tubes?


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Post subject: Re: Crackling noises from reverb unit
Posted: Sat Jan 21, 2017 12:22 pm
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Indeed, I've changed them.


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Post subject: Re: Crackling noises from reverb unit
Posted: Sat Jan 21, 2017 12:40 pm
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Wildstrat wrote:
Indeed, I've changed them.


That doesn't mean the driver tube is not faulty. I bought mine from a reputable supplier but it was faulty straight out of the box. Hence the immediate no questions asked replacement.


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Post subject: Re: Crackling noises from reverb unit
Posted: Sat Jan 21, 2017 12:55 pm
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fifty4 wrote:
Wildstrat wrote:
Indeed, I've changed them.


That doesn't mean the driver tube is not faulty. I bought mine from a reputable supplier but it was faulty straight out of the box. Hence the immediate no questions asked replacement.



+1


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Post subject: Re: Crackling noises from reverb unit
Posted: Sun Jan 22, 2017 8:41 am
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If a new 12AT7 reverb driver tube doesn't fix the problem, try this. If tapping the tube causes the loud static noise, it maybe the jumper on the socket. I've had a couple of new reissued Fender amps and one silverface with this problem. Loud static noise with reverb tube in. No noise with reverb off or driver tube out.

On under side, you'll see that Fender has either folded the socket tangs or inserted a small jumper between pins on this 12AT7, as the two triodes are tied together and act as a single output tube for the reverb. Cold solder = bad contact = noise. Just resolder connection, solves this problem.

You can see a jumper (next to red arrow), on this photo of DRRI.

Image


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Post subject: Re: Crackling noises from reverb unit
Posted: Sun Jan 22, 2017 12:41 pm
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BMW2002ti, not shure if your answer is for this post (crackling) or for the other I have about hum.


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Post subject: Re: Crackling noises from reverb unit
Posted: Sun Jan 22, 2017 1:05 pm
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Loud, static (crackling) noise.


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Post subject: Re: Crackling noises from reverb unit
Posted: Sun Jan 22, 2017 1:58 pm
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Static noise it's a different kind of noise. Crackling is just like loud noise you get from a bad jack plate on a guitar when you attach a jack cable.


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Post subject: Re: Crackling noises from reverb unit
Posted: Sun Jan 22, 2017 2:04 pm
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Oh geez. Whatever...

:lol:


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Post subject: Re: Crackling noises from reverb unit
Posted: Sun Jan 22, 2017 2:11 pm
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BMW2002Ti wrote:
Oh geez. Whatever...

:lol:


Now we know what a veterinarian has to deal with, when his "patient" cannot speak.

:mrgreen:

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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