Dating a marshall amp

Although the envelope was classically glass, power tubes often use ceramic and metal.Some things are very obvious such as non-original or reconed speakers, non-original transformers, replaced pots, re-tweed, re-tolex, re-grill, etc.and these changes are often disclosed and of a non-malicious nature.Clearly Fender wasn’t afraid to use incorrect parts when they were in a bind. The 5G12 Concert is the earliest version from very late 1959 and early 1960 so the existence of a tweed example, while extremely rare, is certainly plausible since Fender was making lots of tweed amps during the same time period.It’s unknown if the tweed covering was a mistake (“Oops, I thought this was a 4x10 Bassman cabinet that I was covering”) or intentional, perhaps as a special order.However, tubes are still used in several specialized applications such as guitar amplifiers (also called a valve amp outside the U.