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Post subject: Re: Super Reverb Reissue, THUMP.
Posted: Sun Aug 10, 2014 7:17 am
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The thump (and the tone, yuck!) only got worse when i changed the rectifier. That being without biasing.


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Post subject: Re: Super Reverb Reissue, THUMP.
Posted: Sun Aug 10, 2014 7:22 am
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Maybe, check the main PSU electrolytic caps. Look for pimples on the side, signs of distortion or bulges on the barrel of each cap, and leakage.

Be sure amp is off and unplugged. Drain any stored voltage from the main caps before opening the doghouse. Do you know how to do this safely?

Changing the rectifier should not have made too big of a difference, provided the replacement was correct type and strong testing.


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Post subject: Re: Super Reverb Reissue, THUMP.
Posted: Sun Aug 10, 2014 7:33 am
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BMW2002Ti wrote:
Be sure amp is off and unplugged. Drain any stored voltage from the main caps before opening the doghouse. Do you know how to do this safely?


Absolutely.

I remember that my very old Fender 75 did exactly this, now when i have relaxed a bit after all that heavy lifting. It also had the thump on the high notes. And i have confirmed that it was not the speaker that caused the thump when i still had the amp.

That Fender 75, died, after i had discovered that it had a thump sound. It sounded like it shutted off when i was practicing with my band and it didnt make a sound for several months after that. I tried everything i could at the time, so i brought it to a Docto-, ahem. Amp tech. He didnt want to touch it because it was so severely very very modified. It has been gutted and is going to be built into something that's a little more.. Simple.


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Post subject: Re: Super Reverb Reissue, THUMP.
Posted: Sun Aug 10, 2014 7:36 am
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Nice close-up photos of the caps under the doghouse would be nice.

Good luck!


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Post subject: Re: Super Reverb Reissue, THUMP.
Posted: Sun Aug 10, 2014 7:49 am
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Feelyfeels wrote:
Nooo-nono.

That's just how they look like.. You know.. The outside!

Mines are all good. No pimples, no bulges, no black spots no nothing.

If you look at the top left cap, that's how exactly how mine looks.


OK... do you have a capacitor tester? Say one that came with a Fluke or some such DVM? If you do, test the first two main filter caps. I believe they are C31 and C32 in the SRRI. If they test ok, prolly rule-out filter caps.

Sure sounds like filter cap or perhaps noisy tubes. How many hours on those 6L6GC's?


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Post subject: Re: Super Reverb Reissue, THUMP.
Posted: Sun Aug 10, 2014 8:05 am
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https://www.youtube.com/watch?v=eVcIc3DmOtM

Here's the caps.
Tubes is GT tubes. I have not bothered replacing them because they're Winged C:s with a Groove Tube logo on them. They came stock in the amp.


Last edited by Feelyfeels on Sun Aug 10, 2014 9:05 am, edited 1 time in total.

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Post subject: Re: Super Reverb Reissue, THUMP.
Posted: Sun Aug 10, 2014 8:30 am
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Resitance tested them since my meter does not have a capacitance mode.
They are all working good!..


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Post subject: Re: Super Reverb Reissue, THUMP.
Posted: Sun Aug 10, 2014 8:57 am
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You Tube link says it's private. I can't see.


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Post subject: Re: Super Reverb Reissue, THUMP.
Posted: Sun Aug 10, 2014 9:05 am
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https://www.youtube.com/watch?v=eVcIc3DmOtM


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Post subject: Re: Super Reverb Reissue, THUMP.
Posted: Sun Aug 10, 2014 9:11 am
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Thanks, for link. Well, the caps look ok. Have you tried new 6L6GC's?


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Post subject: Re: Super Reverb Reissue, THUMP.
Posted: Sun Aug 10, 2014 9:23 am
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Will go ahead and go that. Borrowed my bias probe and i just got it back.

BTW, will those caps take a SS rectifier? 2 350v and 3 500v?


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Post subject: Re: Super Reverb Reissue, THUMP.
Posted: Sun Aug 10, 2014 9:49 am
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The power tube swap didnt do anything


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Post subject: Re: Super Reverb Reissue, THUMP.
Posted: Sun Aug 10, 2014 10:01 am
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For speaker test you can use any impedance, no problem if you dońt play many many hour .

IC caps are illinois , often use anywhere , low end quality.


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Post subject: Re: Super Reverb Reissue, THUMP.
Posted: Sun Aug 10, 2014 10:14 am
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Tested with a EV12L and it massively reduced the thump. It's there, but very vague.


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Post subject: Re: Super Reverb Reissue, THUMP.
Posted: Sun Aug 10, 2014 10:23 am
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Feelyfeels wrote:
BTW, will those caps take a SS rectifier? 2 350v and 3 500v?



Not sure what you mean by this. A cap doesn't care if the source is tube or solid-state rectified. As long as the voltage is within the nominal working range.


Think that it may help posting an audio clip of the offending noise.


Thanks!


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