MIDI cable, 7-Pin delivers power to the MIDI foot controller via pins 6 and 7 ideal for use with Rocktron preamps, amplifiers or effect devices with "phantom power" out Length: 900 cm. Carries A/C power to your footcontroller. Plug either end of the 7-Pin MIDI cable into a MIDI input jack and the other end into the output of your MIDI footcontroller. Plug your footcontroller's A/C adaptor into the receptacle on the back of your preamp, amplifier or effects unit marked "phantom power". (Pins 6 and 7 of the MIDI cable will transfer power to your foot controller).