4
Rev 2.0, 8/1/94
microphone, eliminating the need for external power supplies or
internal batteries. Because the voltage is applied equally to both
sides of a floating balanced circuit, no current flows through the
microphone's transformer, or through the microphone element
itself.
It is often said that the sound of some dynamic microphones is
affected by phantom power, and that ribbon mics cannot be
plugged into an input that is phantom powered. For the most
part these are myths that grew out of difficulties that occured as
a result of some other problem in the mic circuit:
1. When XLR connectors are mated there is no guarantee that
both pins 2 and 3 will make contact at exactly the same time.
It is possible that a damaging current could flow through the
mic for a brief moment under these conditions. However,
this is a connector problem, not a problem with the mic itself,
or phantom power in general.
2. In the past, it was common practice to ground the center tap
of the mic’s output transformer. This is a NO-NO in phantom
powered systems. The solution: locate the center tap and cut
the connection between it and pin 1 of the XLR connector.
3. If the mic's output transformer has developed leakage, the
microphone may become noisy when phantom power is
turned on. Crackling, sputtering or even humming noises
may occur. The leakage, not the power, is the problem. The
solutions are:
A. Turn off the phantom power
B. Put a 1:1 transformer between the mic and the input.
C. Get the mic repaired.
The dominant remote powering system in use today is the
phantom power system which is
compatible
with both
condenser and non-condenser microphones (dynamics, ribbons,
etc.). If your microphone's data sheet says that it is phantom
powered, the SX202 can power it
1
.
The technical requirements for operation and/or compatibility
are:
1
The DIN specification (DIN 45 596) covering phantom
powering specifies the phantom powering voltage as an
open-circuit measurement. If you attempt to measure the
phantom voltage,
make sure that you do so with the
microphone disconnected.
