# Snap crackle pop I have a Super reverb Ri!



## Church-Audio (Sep 27, 2014)

I have a strange one. I have a super reverb ri here that has a strange crackling noise that gets worse with the bright switch engaged and can only be heard when there is a input plugged into the amp.

I have so far 
Changed the plate resistors V1 and V2
Changed the two coupling caps in the V1 and V2
Changed preamp tubes to known good ones. 
I have chopsticked the hell out of the board and I mean the hell out of the board no noise when I do that other than the constant crackling. Not intense crackling just constant. 
I am down to the 4.7k node resistor and the 22 / 500 uf cap that feeds these two tubes. Or possibly the reverb transformer arcing internally. I am going to pull the plate tap and see what happens. I am really out of guesses it does sound like arcing. Turned off the lights can't see anything. If I pull v1 and v2 the amp is dead silent. 

Any other guesses ? The amp puts out a solid 45 watts cleanly.
Biased at 70% no issues solid plate voltage around 450 volts.


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## epis (Feb 25, 2012)

If it's not something else in your shop causing the problem, I would listen to it through another amp, starting from the input stage.


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## Steadfastly (Nov 14, 2008)

Chris: I'm surprised you are asking _us_ for advice. I really have no experience with amps but some with circuit boards so I am wondering could it be a minute crack in the board?


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## Church-Audio (Sep 27, 2014)

Steadfastly said:


> Chris: I'm surprised you are asking _us_ for advice. I really have no experience with amps but some with circuit boards so I am wondering could it be a minute crack in the board?


Why be surprised lol just because I fix Amps for a living does not mean I have encountered every problem and there are lots of really good amp techs on here besides me, I'm not to proud to ask for help


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## Church-Audio (Sep 27, 2014)

epis said:


> If it's not something else in your shop causing the problem, I would listen to it through another amp, starting from the input stage.


Listen to what the tubes?


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## Steadfastly (Nov 14, 2008)

Church-Audio said:


> Why be surprised lol just because I fix Amps for a living does not mean I have encountered every problem and there are lots of really good amp techs on here besides me, _*I'm not to proud to ask for help *_


Humility is a beautiful quality.


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## Church-Audio (Sep 27, 2014)

Steadfastly said:


> Humility is a beautiful quality.


I would never have learned anything about fixing gear without a ton of humility lol. It's hard sometimes every guy or girl out there that fixes gear can relate to that. I know lots of things, but like anyone I get stumped. I hate just guessing and replacing parts for the hell of it. If I'm really lucky, someone has spent the time finding out what this issue is. If not when I do I will share it, so others so they don't have to lose there mind over it  I love that about this place. There are some really smart techs on here, really smar Lots of years of experience. And anyone that does not understand the value of networking and collaboration will find them selves very lonely


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## J-75 (Jul 29, 2010)

DeOxit the pots, maybe?


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## dcole (Oct 8, 2008)

When you say input plugged into the amp are talking about cable and guitar or just cable itself? 

I assume you have tried a different cable/guitar into the amp to eliminate that possibility?

Does the volume of the crackling increase with the volume knob?

Input jacks are all nice and clean? Are they mounted on a circuit board?


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## WCGill (Mar 27, 2009)

Do V1 and V2 share cathode resistors?


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## nonreverb (Sep 19, 2006)

Try this: Put just a phono plug in shorted and see if it still does it.


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## Church-Audio (Sep 27, 2014)

I will do that.


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## epis (Feb 25, 2012)

Church-Audio said:


> Listen to what the tubes?


What I meant was, connecting input of second amp to every stage in your amp starting from the input, so you can isolate the stage with crackling problem.
Usually I make temporary cable with high voltage cap in series to block high DC voltage and 1Meg pot to adjust signal level.


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## jb welder (Sep 14, 2010)

As the bright cap makes it worse, I'm expecting it to be before that.
Both channels?
The weird part is that it goes away with nothing plugged in.
I've recently read of people having noise problems (although different model amps) with caps in the C2 or C7 (treble) positions.


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## jimsz (Apr 17, 2009)

Church-Audio said:


> I have a strange one. I have a super reverb ri here that has a strange crackling noise that gets worse with the bright switch engaged and can only be heard when there is a input plugged into the amp.
> 
> I have so far
> Changed the plate resistors V1 and V2
> ...


I have a similar problem with my SuperReverb. I have chopsticked, resoldered joints, replaced components to no avail. I suspect it's not in the preamp stages, but may be the power tubes that were incorrectly biased.


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## WCGill (Mar 27, 2009)

nonreverb said:


> Try this: Put just a phono plug in shorted and see if it still does it.


Isn't this the same as having nothing plugged in and the shorting jacks closed?


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## nonreverb (Sep 19, 2006)

No...trying to determine if it's the barrel of the input jack itself. Since it goes away with nothing plugged in suggests that it's not necessarily the circuit at all but rather a dirty/corroded jack barrel. bad contact might present itself with just a jack plugged in.
One other thing might be to check solder on the jack itself....long shot but stranger things have happened.



WCGill said:


> Isn't this the same as having nothing plugged in and the shorting jacks closed?


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## WCGill (Mar 27, 2009)

Yes, I had a guy that built amps with old parts because they had "mojo", and replaced input jacks and tube sockets that caused grief but there was nothing physically visible. Old Astron caps too, waste of solder.


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## ampaholic (Sep 19, 2006)

J-75 said:


> DeOxit the pots, maybe?


This would have been my suggestion as well. Seems too simple, especially on an amp that might not be that old, but I've been on a lot of wild goose chases that ended up at dirty or crappy pots!


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## gtone (Nov 1, 2009)

I'm no tech at all, and this is probably pretty far out there but I had a similar problem with a BF Bassman that made a similar low level crackling noise, even though it had just been serviced/given a clean bill of health by a reputable tech Stateside. As well, it only happened when a cord was plugged into the input and yeah, due to the nature of the crackling, got worse with the bright switch on.

For me, problem turned out to be RF interference and/or other frequency noise (X-Box also seemed to have some bearing on it) as V1 to V4 all had no shields. Condition improved marginally putting aluminum shields on the tubes, but completely disappeared with those "tube cages" that the TubeStore sells on V1/V3 and standard shields on V2/V4. Seems my amp was working as a receiver with certain cable/guitar combinations plugged in.


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## Church-Audio (Sep 27, 2014)

nonreverb said:


> No...trying to determine if it's the barrel of the input jack itself. Since it goes away with nothing plugged in suggests that it's not necessarily the circuit at all but rather a dirty/corroded jack barrel. bad contact might present itself with just a jack plugged in.
> One other thing might be to check solder on the jack itself....long shot but stranger things have happened.


Give this man a PRIZE!! after all my troubleshooting it was the input jacks them selves. On this amp they are not the open frame jacks they are closed frame newer style jacks. The pcb board is UPSIDE DOWN  in the amp so you cant really play with the jacks like you can on most fender amps. I took out the whole pcb board plugged a cable in a measured resistance between ground and the shield on the cable guess what??? Over 200 ohms when I wiggled the jacks around.. Not from a bad solder joint but from jacks that are out of spec they are cheap chinese hunks of turd that are not truly 1/4 like they should be. The Neutrik connectors I use on all my cables would not mate very well as a matter of fact even switchcraft jacks had the same issue. Was this from long years of use. No the amp is barely 3 years old. So I will replace all jacks and call it a day. If you have this issue again check the fing input jacks for looseness on the barrel if they are loose measure resistance to ground.. Bet you find 100 to 200 ohms. Even after deoxit they did not get much better. And were generally unreliable. The hint here was the bright switch. That is so early in the circuit it had to be in the front end of the amp. But suspecting that I had not one but 4 input jacks go bad would be a stretch for any tech to figure out. It was interference from my bench area as well because when I moved my guitar a certain way it did go away about 80% thats because ground was not able to do its job. And drain off all that nasty stuff away from the signal.


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## WCGill (Mar 27, 2009)

I've put in Switchcraft jacks and hard-wired them to the pcb because the solder mounts had become unusable. I knew they weren't the best but this is the first time I've heard of conductivity issues. Good job!


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## greco (Jul 15, 2007)

Congrats to nonreverb !!!

I will never forget all the time he spent with me in a GC forum thread (years ago) going into detail about resoldering a broken tinsel wire in a speaker. 
I was sweating over the thought of it alone...and it worked fine. The only thing I could do at that time with a soldering iron was burn my fingers...LOL 

I enjoy these types of thread very much.

Cheers

Dave


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## loudtubeamps (Feb 2, 2012)

Over the years I have seen this happening alot due to weaker metal contacts, varied diameters of offshore components etc. My permanent fix (especially on guitars) is to replace with a stereo jack, using the ring and sleeve as a double ground connection.


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## nonreverb (Sep 19, 2006)

Indeed! I've used the stereo jacks myself on occasion. 
Another way to solve the problem at least temporarily, is to take a piece of emery cloth about 2" x 2", roll it up tight and insert it into the barrel of the jack. Once inserted, unfurl the emery cloth inside the jack barrel. It will fit tight up against the wall of the barrel. Continue to twist it as if unfurling so that rubs against the wall of the barrel then remove. You'll be amazed how much shit is stuck to the emery cloth.....a word of caution though, don't use sand paper as it will sand off the coating in the barrel.



loudtubeamps said:


> Over the years I have seen this happening alot due to weaker metal contacts, varied diameters of offshore components etc. My permanent fix (especially on guitars) is to replace with a stereo jack, using the ring and sleeve as a double ground connection.


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## loudtubeamps (Feb 2, 2012)

nonreverb said:


> Indeed! I've used the stereo jacks myself on occasion.
> Another way to solve the problem at least temporarily, is to take a piece of emery cloth about 2" x 2", roll it up tight and insert it into the barrel of the jack. Once inserted, unfurl the emery cloth inside the jack barrel. It will fit tight up against the wall of the barrel. Continue to twist it as if unfurling so that rubs against the wall of the barrel then remove. You'll be amazed how much shit is stuck to the emery cloth.....a word of caution though, don't use sand paper as it will sand off the coating in the barrel.


So that's where my piece of emery cloth about 2" x 2" got to!! Would that be #600? ..............yup, that's mine. When you are finished, can I have it back, please?


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## greco (Jul 15, 2007)

loudtubeamps said:


> So that's where my piece of emery cloth about 2" x 2" got to!! Would that be #600? ..............yup, that's mine. When you are finished, can I have it back, please?


Your post made me think of this (excuse my very warped sense of humour):

*For Want of a Nail*

_For want of a nail the shoe was lost.
__For want of a shoe the horse was lost.
__For want of a horse the rider was lost.
__For want of a rider the message was lost.
__For want of a message the battle was lost.
__For want of a battle the kingdom was lost.
__And all for the want of a horseshoe nail.
_
​
I think I have some 2"x 2" 600 emery if you need it.

Cheers

Dave


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