Phantom Power Calculator

Calculate 48V phantom power current draw, resistor values, and voltage delivered to condenser microphones through various cable lengths.

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Visualization

How It Works

Phantom power (P48) supplies 48V DC through two matched 6.81kΩ resistors on pins 2 and 3 of an XLR. The mic draws current (typically 2-10 mA), causing voltage drop: V_mic = 48 - I×(2R + R_cable). IEC 61938 requires 44-52V at the mic. Dynamic mics are unharmed because phantom appears as common-mode on the balanced pair (equal voltage on both signal pins). Long cable runs with high-current mics can drop voltage below spec — use heavier gauge cable or a local phantom supply.