than the Stratocaster, although it was not widely embraced by jazz musicians. Instead, rock guitarists adopted it for surf rock. The Ventures, The Surfaris, and The Fireballs were prominent Jazzmaster users. One of the Jazzmaster's notable features is the pickup circuit featuring unusual "roller" thumbwheel controls and a slide switch at the upper neck end of the pickguard. The slide switch selects between two different pickup circuits, the "lead" and "rhythm" circuits. When the switch is in the lead position, the guitar's tone is controlled by the conventional tone and volume knobs and the pickup selector switch. When it is in the rhythm position, it selects the neck pickup only with the brightness rolled off slightly due to different values of the potentiometers (50kΩ vs 1MΩ in the lead circuit), and the volume and tone are controlled by the two thumbwheels; the other controls are bypassed. The intention was that this circuit would allow the performer to quickly switch to a "preset" volume and tone setting for rhythm playing. The lead circuit pot values also stray from Fender's usual spec. Up until the introduction of the Jazzmaster, Fender used 250kΩ pots on their guitars. The Jazzmaster's lead circuit uses 1MΩ pots instead, contributing to its unique tonal characteristics. As a concession to its more conservative audience, the Jazzmaster was the first Fender guitar carrying a rosewood fingerboard instead of maple. The fingerboard had "clay dot" position inlays and was glued onto the maple neck. Some early pre-production/prototype examples came with a one-piece maple neck, others with an ebony fingerboard and/or a black painted aluminum pickguard. Longtime Fender associate George Fullerton owned a 1957 Fiesta Red pre-production body coupled with an unusual and experimental fretboard manufactured in 1961 using vulcanised rubber — reportedly one of two ever made. Rosewood became a standard fretboard material on other Fender models around 1959. The walnut 'skunk stripe' which covers the truss-rod channel on the back of one-piece necks, is absent where the truss-rod was installed from the top, and the rosewood fretboard glued on afterwards. CBS era As with many other Fender models, there are significant differences between pre-CBS models and models made after the CBS acquisition of Fender. The changes implemented by CBS after their purchase of Fender were largely universal, and the Jazzmaster was no exception. A one-ply, anodized (aluminum) gold pickguard was stock from 1958 through mid 1959, after which a