1969 Gibson Les Paul bass owners manual
page 3 - control descriptions
Guitars and Parts for Sale
Whilst this bass had a very fine, but traditional construction, thanks to the inventiveness of Les Paul it was electrically very innovative; there was nothing quite like it in a passive guitar in 1969. "Low impedance pickups offer a new concept in tonal response. The frequency response, tonalities and range of harmonics will exceed that of any electric bass on the market to date."
There was a huge tonal palette to draw from, mainly due to the unique construction and wiring of the pickups. This allowed the selection of all or part of the coils of each pickup to be used, for a cooler or hotter outout, and for the pickups to be wired out of phase. Again this was a brand new sound for 1969 - "Place the phase switch in 'out' position and experience a new and exciting sound".