The original Bassman was solid, powerful and loud. Guitar expert George Gruhn, quoted in noted guitar historian/author Tom Wheeler’s The Soul of Tone: Celebrating 60 Years of Fender Amps, notes that with its advent, Leo Fender “made the first amp that was worth calling a bass amp.”
As is so often the case with Fender amps in the first decades of the company’s existence, evolution proceeded rapidly. Fender was phasing out the TV-front style by summer 1952 in favor of the wide-panel design, and the Bassman was no exception. Restyled with a wide-panel front, the 1953 version (model 5B6) was otherwise essentially the same amp as its TV-front predecessor. At that time, Fender still touted it as a bass-only amp—“It is not a hashed-over guitar amplifier, but an instrument that has been designed for the reproduction of bass and bass only,” the catalog read
A growing number of musicians, however, were finding that the Bassman made a fine guitar and harmonica amp, too. Fender heeded this and soon stopped billing the amp as a bass-only model. And if guitarists were impressed by the tone and power of the short-lived wide-panel 5B6 model of 1953-1955, they were about to have their minds blown by the amp’s next iteration.
To replace the wide-panel style, Fender started building its “narrow-panel” tweed cabinets, which featured less cabinet and more grille in front, in late 1954 for the 1955 model year. In the meantime, back in Fullerton, Calif., Leo Fender and his staff were hearing complaints that model 5B6 couldn’t sufficiently handle low frequencies and that its single 15” speaker tended to blow.