Boss DD-8 Reference Manual page 7

Footswitch connections
Refer to the diagrams for details on the appropriate cables to use and the setting of the polarity switch.
* When connecting a footswitch, you must turn off the power before connecting or disconnecting cables. Failure to observe this
precaution will cause malfunctions.
Connect to TEMPO/EXP jack
Connecting one FS-5U unit
1/4" phone type ,
1/4" phone type
FS-5U POLARITY switch
Connect to TEMPO/EXP jack
Connecting two FS-5U units
Stereo 1/4" phone type ,
1/4" phone type × 2
RING TIP
FS-6 MODE/POLARITY switch
Connect to TEMPO/EXP jack
Connecting one FS-6 unit
Stereo 1/4" phone type ,
Stereo 1/4" phone type
A&B
Connections
Connect to TEMPO/EXP jack
Connecting one FS-7 unit
Stereo 1/4" phone type ,
Stereo 1/4" phone type
A&B
FS-7 MODE/POLARITY switch
7