Yamaha MTX3 Owner's Manual page 12

Controls and Connectors
5. Plug the Euroblock plug into the [GPI] con-
nector or [INPUT]/[OUTPUT] connector of
the MTX3.
NOTE
When connecting unbalanced cables to the [INPUT]
connector, use a jumper wire to connect the "-" and "G"
of the Euroblock.
12
MTX3 Owner's Manual
+ –
G