kick_the_reverb
Joined: Feb 26, 2006
Posts: 1337
Escondido, CA
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Posted on May 25 2006 09:05 AM
Hi amp experts,
I got a question regarding intermittent clicks from my Fender Twin Reverb that I started noticing last night.
Last night, in the process of changing my signal chain I noticed I lost definition in the low end, so I tried a bunch of things (while listening carefuly), and then I started noticing those annoying clicks from my amp.
I isolated it to the amp itself, as even when nothing was plugged into it, it was making the clicks.
I'm probably going to try and tap some tubes to see if it's a microphonic tube, but I'm wondering if anyone had a similar experience and was able to find the source of the problem.
Thanks for any input (and yes, I know that amp bulletin boards are a better place to ask this, but I'm giving this a trial first )
Ran
— The Scimitars
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RevWillis
Joined: Apr 25, 2006
Posts: 83
SLC, UT
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Posted on May 25 2006 10:22 AM
Doesn't sound like a microphonic tube. Maybe a bad capacitor. Try swapping the preamp tubes. Also check both inputs. Or does the amp do the clicking with no input? Does the volume control make the clicking louder or softer?
This can be a difficult problem to nail down. Just have to be patient and work through lots of preliminaries to help locate the problem.
Seems like I had this problem with a Twin. Resoldered a connection to a cap and it went away. But that was just one instance.
Rev.
— www.revwillis.com
www.willisclow.com
www.slajo.com
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kick_the_reverb
Joined: Feb 26, 2006
Posts: 1337
Escondido, CA
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Posted on May 25 2006 10:50 AM
Thanks Rev!
It comes from both inputs and also when there's no input, and I think the volume changes it. It doesn't make the clicking when in standby mode (obviously).
Of cousre this all comes as I don't have the time and money to take it to a pro...
Ran
— The Scimitars
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dp
Joined: Feb 26, 2006
Posts: 3546
mojave desert, california
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Posted on May 25 2006 11:15 AM
the "loss of low end definition" symptom does sound like a bad cap connection /solder joint...
you wrote that the volume control seems to effect the problem, do the tone controls have any effect that you can discern?
you might be able to narrow down the problem further, it might be in a specific tone circuit...
I'd save up a little $$$ for a visit to the Amp Dr...
-dp
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MikeG
Joined: Mar 29, 2006
Posts: 309
Springfield, Oregon
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Posted on May 25 2006 03:01 PM
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kick_the_reverb
Joined: Feb 26, 2006
Posts: 1337
Escondido, CA
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Posted on May 25 2006 03:26 PM
The amp is from 1969, but the it was last serviced around 2004, where it was gone through and retubed(and a few years before that it was rebuilt to Blackface specs).
Thanks for the input,
Ran
— The Scimitars
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RevWillis
Joined: Apr 25, 2006
Posts: 83
SLC, UT
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Posted on May 26 2006 12:25 PM
If the volume control affects the clicking, then I suspect something in the first (preamp) tube. Try replacing it, even with a used tube (is it a 7025 or a 12AX7... either will do).
The volume control is between the first and second sections of the tube (the tube has two sections, or two stages of amplification).
May also be something from the 400 volt power supply to that tube.
Other than tube substitution, not much you can do without taking it to a shop, or driving to Utah!
Rev.
— www.revwillis.com
www.willisclow.com
www.slajo.com
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kick_the_reverb
Joined: Feb 26, 2006
Posts: 1337
Escondido, CA
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Posted on May 26 2006 03:08 PM
Thanks Rev (for the advice and the offer to fix it in Utah  ),
I took it to the shop last afternoon, might be fixed in a week or two (it better, we might have a gig then!).
I figured that since this amp should be in top notch for the Madeira show, I better get it fixed now.
I'll let you guys know what was it (assuming the problem gets solved), so it will stay here for future reference.
Ran
— The Scimitars
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WindanseaBeachBoy
Joined: Feb 26, 2006
Posts: 133
La Playa, Mexico
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Posted on May 31 2006 10:25 AM
Ran, I have heard of this happening because one of the electronic components is touching the mounting board. You might want to look at the board and see if any of the parts (caps, etc.) is in contact with the eyelet board.
It would be an easy fix, it that is the case...
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JakeDobner
Joined: Feb 26, 2006
Posts: 12159
Seattle
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Posted on May 31 2006 12:10 PM
My reverb unit gave me that problem once, it was because an RCA cable was slightly loose.
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dp
Joined: Feb 26, 2006
Posts: 3546
mojave desert, california
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Posted on Jun 04 2006 12:00 PM
I just got my Bassman back from the Amp Doctor; it was in for a similar "odd noise" diagnosis...
When I would play lower register full barre chords (like Bmin or Dmin or F), the amp would produce weird snap,crackle and pop noises...but, not every time...and sometimes it would snap and crackle and pop just sitting there.
It turns out that the 6L6 power tube sockets were loose: new power tubes were recently installed. The tech-dude tightened up the sockets, and the intermitant snap cracle and pop noises are gone.
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kick_the_reverb
Joined: Feb 26, 2006
Posts: 1337
Escondido, CA
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Posted on Jun 15 2006 08:27 AM
So, the problem was:
Noises - loose wires on the board, close to where the tremolo circuit is.
The loss of low end was due to the bias drifting.
The tech went over and replaced some older components that looked suspicious, and also fixed the reverb pan.
I played it at rehearsal last night and it sounded good. Good to have the reverb as a backup, too.
It was $90.
Ran
— The Scimitars
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