Dating blackface amps
This has the benefit of providing ease of access to the inside while providing a strong top.
Fender stopped using the twill covering in 1960, though the Champ was still covered in twill until 1964.
The original Fender amps were tube-powered and the company also started producing solid-state models in the late 1960s.
They are all very rare today and few have survived.
The first amplifiers made in-house by Fender is the Woodie series, built in 1946 through 1948.
They included the Model 26 Deluxe, the Princeton, and the Professional.
Fender amplifiers began making a name for themselves with the Tweed series, so called because of their cloth covering, which is actually varnished cotton twill (tweed is a coarse woollen fabric, commonly used for jackets, coats and caps; it is often woven in a twill pattern, which is likely the reason for the confusion over naming.) They were produced for more than a decade and are now eminently collectible and praised for their sound quality.
While the majority of the piggybacks were produced in blonde tolex, there are a few examples of the brown tolex Bassman amplifiers.