8
Front Panel Controls
Notch & Phase
These controls work to suppress two adjacent
ranges of acoustic feedback. We use guitar
as an example, but the Notch lter and Phase
switch are compatible with all acoustic instru-
ments.
The notch control is a variable frequency notch
lter designed to subdue a resonant peak on
the instrument which is prone to feedback.
Turning the control adjusts the center frequency
of the lter, ranging from 45Hz to 1kHz at full
clockwise. Turn the control to “dial out” the of-
fending frequency.
The in/out switch can be used to bypass the
notch lter altogether.
The phase switch ips the polarity of your instrument signal from posi-
tive to negative, changing its relationship to the sound coming from the
ampli er. One phase setting usually provides better resistance to feed-
back than the other and will vary depending on the instrument and play-
ing environment. Another approach to determining optimal phase is the
selection which sounds or feels most natural when playing.
In certain playing environments the Phase switch may not have an audible
impact.
Lower Feedback
Range
notch
phase
Upper Feedback
Range
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