The SB55 was the first of Yamaha's basses to offer more conventional body shaping, featuring a distinctive 'hook' at the end of the horns which would become something of a trademark.
Along with the J-Type pickups and associated circuitry, the SB55 had a bound neck with a typically Jazz-like slim profile. It offered a clear and clean sound too, which was even noticeable when played acoustically thanks to that Nato body.
There was also a deluxe version offered during this same time span, the SB75, which featured a bound ebony fingerboard with chevron block inlays. These basses were certainly a turning point for the company and along with the top model of the SB series, the SB1200S, they preceded the instrument that would finally see Yamaha recognised as a serious bass guitar manufacturer, the mighty BB.