Phantom power supply

A phantom power supply is an external unit that was included with some Ibanez guitar (and bass?) models with active EQ circuits, such as the Artist 2700P. It may also have been available as a standalone accessory.

The phantom power unit is plugged into an AC outlet. One standard ¼" instrument cable connects the unit to the amplifier while a second cable connects the unit to the guitar's output jack. This second cable needs to be a stereo (or balanced) cable with an extra conductor and special TRS (tip-ring-sleeve) jacks. The unit transforms AC power to 9V DC power, which is fed via the extra conductor in the balanced cable to the guitar. The TRS jacks offer a third contact to deliver this power to the guitar circuit via the output jack. The guitar signal is fed through the other conductor of the balanced cable to the unit, which passes it directly onto the amplifier.

The advantage of the phantom power unit is that it obviates the need for an onboard power sources (typically a 9V battery) to provide power to the active EQ circuit. This eliminates the possibility of having a battery die mid-performance which would impact the tone of the instrument. It also ensures the circuit is fed with a constant voltage level — the voltage provided by a battery can decrease as the battery is depleted.

The unit was introduced for 1977 along with the Artist 2622 and was later sold with some other models. It works without modification with any active EQ model wired with an LED (e.g. AR500, MC550, AR5000, 2700). Other models from the Artist, Musician and Studio series may need to be rewired to work with the phantom power unit (see wiring diagram below).^[1]