PreSonus Acousti-Q - Manual (Page 8)

6
2 CONTROLS & OPERATION
Phase
The phase of the signal from the mic may be reversed to change it’s sound. The
inverted phase results in a signal that sounds more wooden and hollow. This
sound is much like the sound of single coil pick-up electric guitars such as the
Fender® Stratocaster™. It can be especially effective for rhythm guitar.
2.1.2 NOTCH FILTER
The ACOUSTI-Q has been outtted with a Notch
lter for controlling feedback without greatly altering
the instrument’s sound. A Notch lter affects a very
narrow frequency bandwidth with minimal overlap into
adjacent frequencies. This is why a Notch lter can
virtually eliminate a feedback problem while retaining
an instrument’s original sound. The dual concentric control for the Notch lter
has an inner knob that selects the frequency to be ltered and an outer knob
to select how much the selected frequency is boosted or how much the selected
frequency is reduced.
Frequency
The Frequency control (inner knob) of the Notch lter’s dual concentric control
is labeled FREQ. The frequencies governed by this control are graduated
incrementally from 92Hz (inner knob rotated completely counter-clockwise) to
494Hz (inner knob turned completely clockwise). These frequencies are effec-
tive at controlling feedback because they correspond to the speed of the vibra-
tions of specic musical notes (ex. 92Hz=F#) that may resonate (feedback)
inside an acoustic instrument such as a guitar. The shape of the instrument,
the density of the material from which it was manufactured, as well as the
volume that the instrument’s signal is being amplied and reverberates inside
the instrument all play a role in why an amplied acoustic instrument may
feedback.
Level
The Level control is the outer knob of the Notch lter’s dual concentric control.
Notice that the markings for this control have a zero (0) at the twelve o’clock
(straight up and down) position. With the outer knob set at this position,
the Notch lter has no effect on the signal. Rotating the control fully counter
clockwise reduces (cuts) the frequency that has been selected by twelve dB
(12dB). Bringing the knob back to the top or twelve o’clock position adds back
the selected frequency until it is completely restored at the twelve o’clock (0)
293
92 494
0
-12 +12
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