4. Phantom Power
Condenser microphones, active DI boxes, etc., require a power supply. If this cannot or should not be done via a battery or an additional power connection, so-called phantom power provides the option of voltage supply via the balanced signal cable.
The significance and advantage of phantom power (compared to the many earlier, non-standardized power supplies used by manufacturers) include the fact that symmetrically connected devices that do not require a power supply cannot be damaged by it because both signal-carrying conductors have the same potential (usually +48V) and therefore no potential difference. While dynamic microphones are not affected by activated phantom power, it can even destroy ribbon microphones! So, if you intend to use condenser microphones and ribbon microphones simultaneously, make sure that phantom power can be individually switched on for each channel (often, there is only one switch for all channels at once).
In the case of unbalanced line connections, it is advisable to turn off phantom power since, in this situation, only XLR Pin 2 carries +48V, while bridged XLR pins 1 and 3 are short-circuited. Not all connected devices can handle a direct current-carrying conductor. In rare cases, this can also lead to damage.
If the mixer being used does not have switchable phantom power for each channel, it is recommended to operate unbalanced signals (e.g., from a CD player, effects units, keyboards, etc.) via line inputs or to use a DI box in between.
