The circuit change and the cosmetic change didn’t happen at the same time some 1967 and early 1968 Bandmasters still possessed the AB763 circuitry. It is referred to at times as the “silverface” circuit, referring to the brushed aluminum control plate used from 1968 to 1974. The AA568 version (introduced May, 1968) was met with popular dislike by Fender’s customers. Later “silverface” amps retrofitted to this circuitry are described as having been “blackfaced,” a reference to the black faceplate used on these amps during much of this era. Some 1964 blackface Showmen were still covered in blonde Tolex rather than the usual black. The complex brownface “harmonic vibrato”, however, was replaced by a simpler electro-optic oscillator. The AA763 (July 1963) and improved AB763 (March 1964) (“blackface”) circuit is arguably considered the “best” circuit version produced for this amp by collectors and aficionados. The new model was covered in Tolex rather than “tweed ” still a combo in brown Tolex for 1960, and then a blonde-covered head-and-cab piggyback 1961-63. The 6G7 and revised 7-A circuit used the long-tail pair phase inverter introduced with the 1957 Bassman, used a solid-state rather than a tube rectifier, and also included a vibrato that is heralded as Fender’s best by many enthusiasts. “Blonde” aficionados feel this circuit has superior tonal characteristics when overdriven, to the AB763 circuit. The circuit was used from 1960 until July 1963 when the “AB763” circuit was introduced. The 6G(n) (“brownface”) circuit was used in several Fender amplifiers, including the Bandmaster. Phase inverter changed to cathodyne (concertina) type. Negative feedback and filter choke added, and the output section given fixed (grid) rather than cathode bias. the 6SC7, to nine-pin mini-tubes of the 12A(n)7 family, as well as the introduction of the floating-paraphase inverter.
The D-series circuits represented Fender’s shift from octal preamp tubes, e.g. Like the other larger Fender amps, the Bandmaster used cathode-biased 6L6G output tubes, a 6SC7 paraphase inverter, and two more 6SC7s in the preamp with a 5U4 rectifier.
#AB763 BANDMASTER PRO#
The first Bandmaster was in all respects almost identical to the Fender Pro, a dual-6L6 26-watt amp with a 1×15 speaker, with one difference: separate treble and bass controls, where the Pro like all other Fender amps to that time only had a single “Tone” knob. In the 2000s, vintage Bandmaster amps remain in use by blues, Americana and rock and roll bands.Ībove: Fender Bandmaster, silverface, 1968 “drip-edge” with AB763 circuit Beginning in 1960, Bandmaster amps were equipped with a vibrato effect. Some early models had both a microphone input and instrument inputs. It was introduced in 1953 and discontinued in 1974. The Fender Bandmaster was a musical instrument amplifier made by Fender. The "universal" changes do seem to be the oscillator circuit, cathode resistor change from 56K to 100K, and the addition of the 1500-ohm grid stopper resistors.Above: Fender Bandmaster, model 5G7, early 1960 The Bandmasters also saw no change in tone stack cap values between the AA763 and AB763 circuits. And for other models, the tone stack did not change from. 033 cap would yield slightly more midrange, but I don’t think it would be very noticeable.įor some models like the blackface Concert, there was no change in phase-inverter resistor values, and no changes in tone stack cap values (fascinating!). The only major difference in tone between the two circuits would be attributable to the different tone caps (.033 vs.047). The most important difference is the addition of the grid stoppers (safety first!).
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