47
the DC power is applied common-mode. The
audio travels via pins 2 and 3, the power trav-
els between pins 2 and 3 simultaneously, and
pin 1 is the ground for both audio and power.
Microphones that do not require power simply
ignore the DC present between pin 2/pin 3 and
pin 1. If you measure with a voltmeter between
pin 2 and pin 3, you will read 0 Volts DC. This
is what your dynamic microphone sees. Measur-
ing between pin 2 and pin 1, or between pin 3
and pin 1, you will read the phantom power
voltage, usually 48V, without a microphone
connected. The dynamic microphone, as well as
your balanced mixer input, ignores this voltage.
Lately, the term phantom power has been
perverted to refer to any remote powering
system. In the strict sense of the DIN standard,
this is not true. Furthermore, microphones or
transducers that claim to use this system are
not compatible with the DIN standard and will
almost certainly be damaged if connected into
such a system. Fortunately, these systems use
tip-ring-sleeve phone plugs or miniature XLR
connectors and they are usually associated with
instrument pickup applications
2
.
Phantom powering is defined in DIN standard
45 596 or IEC standard 268–15A. Your Mackie
Designs mixer conforms to this standard.
What works?
To be compatible in a phantom powered
system, a device (microphone, preamp with a
microphone-style output, or direct box) must
have a balanced and floating, low-impedance
output. This includes all microphones commonly
used for sound reinforcement and recording,
such as the Shure
®
SM58, SM57, Electro-
Voice
®
RE-15, RE-16, RE-20, ND series,
Beyer
®
M160, M500, AKG
®
D224, D12, D112,
and
many
others.
If you are fortunate enough to own any tube
condenser microphones, such as the AKG
®
C12,
Neumann
®
U47 or U67, these microphones
may be connected in a phantom powered system
and will operate without regard to the presence
or absence of phantom power. They will always
require their external power supply (which
must be plugged in and turned on).
What doesn’t work?
The list is short:
1.
Microphones with unbalanced outputs.
2.
Microphones with grounded center-tapped
outputs. Many old ribbon microphones were
supplied connected this way. Have a techni-
cian lift the ground from the center tap.
3.
High-impedance microphones.
4.
Microphones that exhibit leakage
between pin 2 or pin 3 and pin 1. These
microphones will sputter and crackle
when phantom power is applied and will
work fine when you turn off the phantom
power. Get the microphone repaired.
2
There is another remote powering system called A-B or
T-system powering. It uses pins 2 and 3 to carry both power and
audio. It is not compatible with dynamic microphones or phantom-
powered microphones.
Worry about your other microphones as long
as their output is balanced and floating.
Connect microphones or devices that do not
conform to the DIN 45 596 standard.
Don’t connect A-B or T-system microphones
(another remote powering system) without
suitable adaptors.
PHANTOM POWER DO & DON’T CHART
DO
DON’T
If you are plugging in a condenser microphone,
do verify that your microphone can be
phantom powered.
Ensure that the microphone’s output is low
impedance, balanced and floating. This is
especially important for vintage ribbon
microphones like the RCA 44BX and 77DX.
Mute the sound system when turning the
phantom power on or off, or when connect-
ing or disconnecting microphones. If you
forget, the resulting loud, nasty POP may be
your last.
