PSB Speakers PSB SubSeries 500 Guide D'utilisation page 11

Adjustable Rubber Leveler and Adjustable Spike Installation
Screw the supplied levelers or spikes into the threaded inserts located in
the base, bottom or in the four feet attached to the bottom of the
subwoofer. Speaker spikes are for carpet use. Threaded rubber isolation
levelers are for shelf or hard floor use.
a) Carpet Use
Screw a spike with a lock nut attached into the insert located in the
base, bottom or in each of the four feet attached to the bottom of the
subwoofer. Locate the subwoofer, adjust to the desired height
(higher for thicker carpet) by turning the spikes and tightening the
lock nuts.
b) Hard Floor or Shelf Use
Screw a threaded rubber isolation bumper with a lock nut attached
into the insert located in the base, bottom or in each of the four feet
attached to the bottom of the subwoofer. Locate the subwoofer,
adjust to the desired height by turning the rubber isolation bumpers
and tightening the lock nuts.
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