Dating a fender bass
Many professional music industry analysts have heralded the 1950s Fender 4×10 Bassman amps as the greatest guitar amp ever.The first 1954 Fender Tweed 5D6 4×10 circuit generated further Tweed Bassman amplifier development through 1960.Similar preamp changes were also incorporated in the 5F8 Twin Amp at about the same time, but not on other large size Fender amps.During 1958, Fender introduced the model 5F6-A Bassman model.Produced from 1954 until 1960, these models are called the "narrow panel" tweed amps .Fender introduced the model 5D6 "DK" in November 1954 followed by the 5E6 Bassman Amp during early 1955.with a front panel that had a rectangular grill cloth with rounded corners and looked much like a television of that era.
It was designed to generate 26 watts at an 8 ohm impedance load, and offered a cathode-based bias.
The 5E6-A Bassman model was introduced later that year and included some evolutionary improvements.
In July 1957, Fender introduced the model 5F6 Bassman.
No schematic for the 5D6 circuit has ever been found, but Ken Fox and Frank Roy have created a few from originals, and copies are freely available online.
Only 11 of these early 5D6 Bassman examples are known to have survived.