Speck Electronics SSM - Manual (Page 50)

Chapter 4 Operation Section
When used, this switch disconnects the shields (pin 1) from the left and
right balanced XL connectors thereby inducing any piece of gear
interfaced at these points to search out a ground path external to the
Model SSM. This can reduce the chance of ground loops and eliminate
unwanted hums or buzzes.
The operation of the Ground Lift Switch does not affect the program
feed's unbalanced 1/4" jacks.
These unbalanced 1/4" T.S. phone type jacks are available for hooking
up a power amp that would be used for keyboard rack speakers or stage
monitoring system. The signal present at these jacks is adjusted by the
Monitor Master Control on the front panel.
This 1/4" stereo jack is a duplicate of the front panel headphone jack
(see the front panel Master Section) allowing a second set of stereo
headphones to be connected to the SSM.
Although not required, it is recommended that headphones of the same
type and impedance be used when using the front and rear headphone
jacks.
The tip of the stereo jack is the left headphone signal, and the ring of the
jack is the right headphone signal.
This 1/4" jack is similar in operation to the headphone feed but with its
signal level modified to allow interface to a wireless headphone system.
The transmitter feed signal is a mono composite of the left/right
headphone signals and may be updated in the future for stereo operation
when stereo headphone transmitters become available.
The level for the transmitter feed is adjusted with the Headphone Master
Level on the front panel. The use of the Transmitter Feed Jack does not
affect the operation of the front or rear stereo headphone jacks.
13. Monitor Feed Jacks
14. Stereo Headphone Jack
45
12. Program Ground Lift Switch
15. Transmitter Feed Jack