The Steel Guitar Forum

Can anyone tell me what makes the vibrato happen in the Fender Vibro-Champs? My Super Reverbs have a pulsating light but the VC does not. My VC has lost almost all of the intensity and it's not the 12AX7 tube. I've changed that out to no avail.

Thanks in advance for any advice.

Field Guide tells me that the VC is a bias trem as opposed to the Super's opto-trem so there's why you see the light thing in the Super and not the VC. The quick first answer with an opto is to replace the 'roach'. Unfortunately I have no idea what's the simple answer for your type. So with 2 bux and my answer you can go buy yourself a cup of joe. Sorry.

Vibro Champ is definitely a bias-modulation tremelo circuit. Same for the Princeton/Princeton-Reverb.

Usually when I've seen one of these tremelos go south, it's either the tube, a resistor which has drifted in value, or a capacitor which has drifted or is leaking charge. This tremelo circuit is very simple and the diagram readily available - one needs to check voltages & component values, check for capacitor leakage, and replace any problem parts.

But you should only do this if you know what you're doing. You can kill both yourself and the amp if you don't, no joking. This isn't a big job for a qualified tech to do, but don't "fool around" in there yourself if you aren't savvy with tube electronics.

I prefer the bias modulation tremelo on Fender amps to the larger-amp blackface/silverface version with the optical element. I used to have a speaker-tap line-out on various Vibro Champs and Princetons to drive other amps. I should really do this to my current one.