1979 Bandmaster Reverb question

I think I remember reading that there the bias adjustment was one of the differences in the blackface-silverface development. If so, you can find details on changing it on any of the online Vibroclone guides (how to convert a sf BMR to a bf VibroVerb).

 

The BMR's with those controls are probably the late 70s ultralinear 70 watt versions. They are not easily blackfaced because of the different power supply (SS rectifier, higher voltages) and UL output section.

Those amps are pretty good amps in their own right. They're not going to sound as organic as a BF or early SF, but if you like a tight, responsive, loud and clean tube amp, they're the ticket.

Jef

 

The balance pot can be rewired to be a "true bias" pot by a tech. This is highly recommended.

All you'll need then is a bias probe similar to a Bias Rite www.webervst.com and you'll be all set. No scopes or signal generators required.