Dating fender twin reverb
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.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.
Either way, this under-whelming overdrive tone—together with the master volume and other post-1967 circuit changes—is why your amp is, in your words, maligned.
Remember, your amp is newer than the newest component.
For example, if you find pots from late ‘64 and transformers from early ’65, you can be pretty sure your amp is a 1965.
Some players actually prefer these models, however, because they tend to compress more easily than any other Twin.
According to the dates on Fender schematics, these “improvements” only lasted for a year.