Roland GK-2B Owner's Manual page 7

Names of Things and What They Do
(6) Select switch
This switch selects the sound that is output
from the connected GK-compatible device.
In the "BASS" position, the normal pickup
sound of the bass will be output. In the "MIX"
position, the normal pickup sound of the bass
and the sound of the GK-compatible device will
be mixed and output. In the "GK" position, the
sound of the GK-compatible device will be
output. For details, refer to the owner's manual
for your GK-compatible device.
(7) S1 switch
(8) S2 switch
The functions of the S1/S2 switches differ
depending on the GK-compatible device you
are using. For details, refer to the owner's
manual for your GK-compatible device.
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