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Topic: Vibrolux Tremolo/Reverb Questions |
Chris Bauer
From:
Nashville, TN USA
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Posted 2 Oct 2016 11:27 am |
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Okay Fender amp mavens...
I got an original SF Vibrolux in a horse trade. I LOVE the sound of it but:
1. The reverb seems to be pretty much all or nothing. So, it's no reverb or 'Grand Canyon' reverb with not much in-between.
2. The tremolo is kinda 'meh'. I usually love Fender trem but this is pretty anemic.
Any idea whether or not these are typical problems for just-past drip edge Vibroluxes and, in either case, what - if anything - I can be doing to fix either or both?
Thanks! |
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Dave Mudgett
From:
Central Pennsylvania and Gallatin, Tennessee
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Posted 2 Oct 2016 12:23 pm
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BF/SF Vibroluxes of all periods, when tuned up, can have good reverb and tremelo. But between build tolerances and components drifting out-of-spec over the years, the actual performance in old (and even new) examples can vary.
On the reverb: first, is the reverb pan plugged in the correct direction? Try reversing and see if it's better or worse. Next I'd suspect the reverb pan, and good replacements are available. If you have (or can beg/borrow) another known-good BF/SF reverb pan (even in a different BF/SF amp), try running this Vibrolux's reverb in/out into that pan and see if that fixes it. Another thing you can try without buying or taking anything apart is to sub the reverb driver and/or recovery tube(s) with known good ones. Beyond that, you're probably down to looking at the reverb driver/recovery circuit itself, including the reverb drive transformer. I suppose the reverb pot could be funky, but I think that would be unusual.
On the tremelo: lots of older BF/SF amps have weak tremelo. Sometimes I have luck subbing the tremelo's 12AX7A with a known good tube. But more often than not, either resistors/capacitors in the tremelo circuit or the "bug" have issues. If capacitors are leaky at all or resistors have gone out of spec, it can definitely affect either the intensity and speed of the tremelo, or both.
Try the simple stuff first. But I've never seen a BF/SF Fender with reverb/tremelo that couldn't be brought back into good shape yet, provided the amp itself wasn't hosed. |
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Ken Fox
From:
Nashville GA USA
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Posted 2 Oct 2016 3:46 pm
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--The reverb seems to be pretty much all or nothing. So, it's no reverb or 'Grand Canyon' reverb with not much in-between.
The tank will not produce any reverb if plugged in backwards, The fact that you are getting reverb at all means it is plugged in the correct way. The reverb return goes from almost nothing to full on. That is likely an issue with the reverb return circuit. The reverb control pot may be bad or possibly not be grounded??
On the tremolo I would suspect a tube first or possibly a weak tremolo bug. The tremolo bug is usually the culprit |
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Chris Bauer
From:
Nashville, TN USA
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Posted 3 Oct 2016 6:15 pm
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| Thanks Dave and Ken! |
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Carl Mesrobian
From:
Salem, Massachusetts, USA
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Posted 4 Oct 2016 4:08 pm
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The first thing I would check is the braided shield on the rca plugs into the back of the amp. See if they are broken off or have become intermittent. See the reverb input reverb output connections below. Note how the braid is starting to fray 
Then I would see if the reverb tank is bad by substituting a known good tank. There are tiny gauge leads to the transducers in the pan that can break from the amp being bounced around. Note the black/white and black/red pairs of wires, and the spring to transducer connections. Those are the weak spots.
https://www.amplifiedparts.com/tech-corner/spring-reverb-tanks-explained-and-compared
Tremolo - probably the bug, or one of the caps in the tremolo circuit
Finally the tech's secret - the chopstick test!! Tapping parts while the amp is on - if aloud pop makes you jump 10 feet, then there's a loose solder joint or bad component.. keep the reverb volume low!
EDIT - great amp, by the way
_________________
--carl
"The better it gets, the fewer of us know it." Ray Brown |
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