Dating blackface amps
During the different eras the Bassman amp came in many different shapes and configurations.Few other models experienced so many changes in terms of looks and tone.There is not a huge amount of gain in the preamp stages of a Twin Reverb, at least not enough to achieve significant overdrive. One explanation might be to allow the amp’s preamp section to be overdriven by an external gain-boosting device, such as the Electro-Harmonix LPB-1 or the Dallas Rangemaster, both popular in the late ’60s and early ’70s.Turning up the channel volume allowed increased overdrive in the preamp section, with the overall volume of the amp controlled by the newly added master volume. But the engineers at Fender took it a step further, adding the ability to access more gain internally.I just got a ’70s silverface Fender Twin Reverb that needs a little TLC.Surfing the various forums, I’ve learned that this master-volume edition of the Twin is one of the most (unfairly, to me) maligned designs.You can easily identify these 1968 amps by the silver-metal band around the perimeter of the grille cloth.
It was introduced in 1951, primarily targeted for bass guitar players and promoted as a bass amp for the Fender Precision Bass guitar, the first mass-produced electric bass guitar ever.This boost is activated via a master volume control with a push/pull switch. From the most unlikely of places: the reverb drive signal!The reverb drive circuit in most tube-driven reverb amps is actually similar to a small, low-power, single-end output stage.Blackface Twin Reverbs are the most coveted versions of this amp.With their stated power of 85 watts, they are the most powerful Fender amps of the era.