The Fender Bass VI was a short scaled (30 ") six string bass. Available from 1961 until 1975. The factory tuning was simply one octave lower than typical six string guitar tuning. Notable users include the Beatles (widely used in the studio, not just by Paul), Jack Bruce of Cream, and Eric Haydock of The Hollies.
The following description is taken from the 1969 Fender Lovin' Care catalog
Built with both the guitarist and bassist in mind, the Fender Bass VI is tuned one octave below the standard guitar. Numerous tone combinations are made possible with three adjustable full-range pickups. The circuit incorporates three on-off switches, one for each pickup, plus a tone modification switch enabling the player to select the pickups individually or in any combination. In addition, a tone control permits further modifications of any selected position. Chord structures and fingering are identical to the guitar, thus, both guitarist and bassists will find the instrument easy to play and adapt to their present orchestrations and instrumentation.
Among other outstanding features of this instrument are the 'floating tremolo' action ..smooth and positive return to pitch and a 'Trem-Lock' permitting simultaneous string change. The Fender Mute and reinforced fast action neck with trim and inlaid position markers are additional features employed. Micro bridges are individually adjustable for perfect string length and a master bridge adjustable for height. Comfortable playing over long periods is achieved with the 'off-set' waist design. In addition to Shaded Sunburst, the Bass VI comes in selected custom finishes.