Epson EMP-7500/5500 Owner's Manual page 39

2. Connect the cable's 3.5 mm stereo mini-plug to the
projector's Audio Out jack.
3. Connect the other end of the cable to the external speaker
or PA system.Ensure you to connect the red RCA plug to
the right channel and the white RCA plug to the left
channel.
RCA/3.5 mm cable
Connecting to an External Speaker or PA System 19