The L6-S Custom, like the Gibson Ripper bass was equipped with the newly developed "Q System". Contemporary L6-S advertising describes it as follows:
...two incredibly hot Super Humbucking pickups wired for series, parallel or single performance ...a six-position tone selector ...plus volume, treble and mid-range controls. The result is a texturizing, tone-tailoring capability second to none.
We haven't heard a more powerful pickup than the new design Super Humbuckings on the L6-S. The notes are extra loud, with enough sustain to live on when others die. And six different sound settings let you deliver any music style from country "chicken pickin'" to the most abstract jazz riffs.
THIS SIX POSITION CONTROL regulates the choice and blend of coils in the new design Gibson Super Humbucking Pickups. Each position will offer unique tonal values when combined with the midrange and tone controls.
Position 1 Both pickups, in series, in phase (wiring in series results in a bit more high end bite).
Position 2 Activates the front pickup only.
Position 3 Activates both pickups in a parallel, in phase configuration.
Position 4 Activates both pickups, parallel out of phase for a "dirty" type tonality.
Position 5 Activates the back pickup only for the maximum in treble response.
Position 6 Activates both pickups in series out of phase.
MASTER VOLUME CONTROL The master volume control regulates the signal output of both pickups.
MIDRANGE CONTROL To add midrange response, turn the control clockwise. Position 10 will offer maximum midrange response.
TONE CONTROL The tone control regulates the treble and bass tonalities. Position 10 will offer maximum treble response. Position 0 will offer minimum response.