Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: mrjomo on November 25, 2025, 06:28:18 pm
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My friend is a “Custom” Vibrolux Reverb. It has been modded to with Fromel kit. Schematic will be attached. Couple mods I will change back; another I will mod the mod.
Issue is that reverb return is INSANELY hot (by my boring taste).
1) The pot goes from nothing to way-too-much in the space of 5 degrees of rotation. It just gets louder from there. 1 item is that the pot has a linear taper. Maybe this has something to do with it, but I fail to believe that it explains it all.
2) I just replaced the tank from (i assume) stock to a MOD tank. It’s supposed to be spec’ed as a replacement… I was a moron and fried the old one.
3) It just seems to me that there is a whole ton more gain in the reverb send >> Return than is needed; certainly more than I want.
I can readily imagine knocking the reverb signal down by 12dB. At that point, there might be some useful control with the knob.
Part of the Fromel mod scheme was to separate the two channels such that only Bright feeds the reverb. I don’t recall how “it sounded” before I did that. That was a while ago.
I usually use a Strymon Flint for its reverb and tremolo. It just seems to me that this thing still should work…
I welcome yer wisdom. Thank.
JoMo
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Fender reverb is Fender reverb. Most of it is more than you need when the amp is being played quietly. But it’s designed to be good at gigging volumes - i.e., in situations where people acquire Fender Reverb amps for gigging. Peeps who buy Fender reverb amps expect this. If you mess with it, some later owner is going to want to undo the mods you make. So maybe sell the amp unmolested as it will have higher resale value this way. And get another amp with less intense reverb. YMMV
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ah, yes. so sensible. i’ll keep having a nice time with the Flint.
thanks!!
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The modification to R26 is significantly increasing the reverb drive even over traditional Fender reverb levels. I'd be inclined to snip out C14 if you're going to leave that value in place. This way the drive behaves more like the later Silverface amps with a lower value cathode resistor and no bypass cap.
I'd also look at an audio taper. I buy the snap in pots for the reissue amps and have changed all of mine to audio reverb level pots. Customers request this as well after trying my amps out. It's a safe modification because all the the reverb level is still accessible--you just get better control over the lower end of the range.
Finally R32 is a good place to experiment. Lowering this will increase the dry signal and attenuate the reverb signal a bit. I'd try that last if the other two tweaks don't get you there.