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In article writes:

Here's a bit of a trap for young players, or those who assume phantom = 48
volts. The old warhorse Shure FP42 four mics input field mixer (its been
around a long time !) actually has a published spec of 30 volts phantom
power, not 48...

The Shure Pro Master mixer provided 12V for phantom power, so they
make the SM81 mic (roughly contemporary) so that it would work on 12V.
The Mackie PPM series of powered mixers provide 15V for phantom power
(it's just tapped off the IC power supply positive rail).

Read the specs!

One spec that's rarely published is the total amount of current
available from the phantom supply. It doesn't seem like it should be a
big deal, and it isn't if there's a real power supply for the mics,
but often this is a place where manufacturers save money. Nowadays
with common and inexpensive condenser mics, it's not unusual for a
mixer to have nearly a "full house" of mic power, but half a dozen
years ago, some mixers derived phantom power using a voltage
multiplier, or a low current winding on the power transformer. They
were betting that only about 1/4 of the channels would need power, so
instead of having enough current for a reasonably greedy mic on every
channel, they limited the current available. Plug in too many
condenser mics and the voltage to all of them drops, sometimes to the
point where a mic no longer works properly.

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