What is phantom power? How is it provided to the XLR input?
Phantom power is DC voltage sent down the microphone cable to power the preamplifier of a condenser mic capsule – sometimes through a power module. The power module attached to the microphone unit converts the 9 – 52VDC into a small bias voltage that the microphone capsule needs to operate. A balanced mic cable has three conductors; Pin 1 is ground, Pin 2 is audio positive, and Pin 3 is audio negative. Most microphones produce a positive voltage on Pin 2 when sound pressure is applied to the diaphragm. Phantom power is 9 – 52VDC applied across Pin 1 and Pin 2 – and at the same time applied across Pin 1 and Pin 3. The term ‘phantom power’ was assigned because if you take a measurement across the two audio lines – Pin 2 and Pin 3 – you find 0 Volts DC. The voltage does not affect the mic signal.
