Metropoulos Forum

Hi All,

I recently converted my beloved Bandmaster Reverb into a Vibroclone. The amp has always had a little issue with the reverb feedbacking at high levels. The feedback starts 6 or 7 up to 10 on the reverb control. I've replaced the tank already. When I got it it had a TAD 9AB3C1B which I changed to a TAD 4AB3C1B. Unfortunately it has the issue with both tanks. It did it as a head, and it still does it now as a combo (hasn't gotten any worse in the vibroverb cab). If I remove the tank from the combo, the feedback goes away, when I put it back in, it comes back. The amp already has the 2000pf cap installed at the jacks to reduce feedback and noise. I've tried various positions of the tank inside the cab, I've messed with how tightly the tank is screwed down and I've wrapped it with various materials, added rubber washers under the screws, added weather stripping on the tank itself etc.. nothing seems to solve the issue. Does anyone have any ideas what I should be trying next?

Thanks!

Problem sorted! For anyone wondering, this last batch of tanks from TAD seems to have this issue apparently... Both my TAD tanks seem to do this but my Accutronics and whatever is in my Super Reverb (not sure, too lazy to check ) are problem free! I now have a new Accutronics tank on the way!

I think this is the reason that Fender use to place their tanks in vinyl bags which were laid in the bottom of the cabinet and not attached with screws. I am not certain that they used this method on every amp over the years but many I have had used this method. Mounting the tank with screws will increase the chance of feedback caused by the cabinet's vibration. I have also read that some techs have used CA glue to secure the transducer inside of the reverb tank to prevent vibration and feedback. Glad to hear that a different tank solved your issue.