M-Audio Octane User Manual page 7

and rumbling. Pressing and locking the Lo-Cut Switch in the IN position will insert a high-pass filter which will attenuate frequencies
below 80Hz at a rate of -12dB per octave.
When using a stereo (two microphone) configuration, it is not uncommon for the two channels to have phase-cancellation problems.
Phase Inversion Switches (Ch 2, 4, 6, 8)
This can often be corrected by reversing the phase of one of the two microphones.
NOTE: The best way to hear the effect of phase reversal is to listen to a stereo source, such as an acoustic guitar being
recorded with two microphones. Pan the channels hard left and hard right, and listen as you press the even-numbered
channel's Phase switch. You should hear the stereo sound "open up," and become more wide and "solid" sounding in one
position or the other.
Condenser microphones need to receive a DC voltage (generally +48V) from an external source in order to generate an output signal.
Phantom Power Switches
While some condenser mics come with their own power supplies or internal batteries, the majority require phantom power to be
supplied from the preamp or mixing console.
Pressing and locking the Phan 1-4 or Phan 5-8 switches to the IN position will activate phantom power, supplying +48VDC to the
associated group of four input channels. Always make certain to connect your microphone before turning on phantom power.
Conversely, make certain to turn OFF phantom power before disconnecting your microphone.
Most dynamic microphones are unaffected by phantom power, however some (primarily older) ribbon microphones can be damaged by
it. Do not use phantom power with unbalanced microphones. When in doubt, check with the manufacturer of the microphone in question.
NOTE: When using channels 7 and 8 in M-S Matrix mode, connect your Mid (Cardioid) microphone to channel 7 and your Side
M-S Matrix
(Figure-8) mic to channel 8.
Pressing and locking the M-S Matrix switch in the IN position engages the M-S matrix encoding circuitry on channels 7 and 8. The Width
control regulates the relative balance of the Mid and Side signals. Turn it fully counter-clockwise for minimum Side signal (less apparent
width), or fully clockwise for maximum Side signal (more apparent width).
A word about M-S Matrixing: The M-S (Mid-Side) miking technique was created by renowned inventor Alan Dower Blumlein, credited as
the originator of stereophonic recording. While the more commonly-used X-Y miking techniques involve placing two microphones in a
coincident pattern (usually aimed approximately 45 degrees left and right of the intended source), M-S miking aims one microphone
directly at the source, using a cardioid pickup pattern; the second microphone is aimed sideways using a bi-directional figure-eight
pickup pattern. The M-S matrix encoder then sums the Mid and Side signals (M+S), sending it to the left channel, and subtracts the
signals (M-S), sending it to the right channel. By adjusting the relative balance of Mid and Side signals (with Octane, this is accomplished
with the Width control), the optimal stereo image can be created. A major advantage of M-S miking is mono compatibility, in that there
is less potential for phase cancellation when the stereo signal is summed to mono, which is a risk with X-Y technique.
The illustration below shows the pickup patterns of two microphones arranged in M-S stereo placement.
M
+S
-S
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