About Acoustic Feedback; Power Switch - Fishman Loudbox Owner's Manual

Phase
Use the phase switch in conjunction with the Anti Feedback filter to
eliminate acoustic feedback

About Acoustic Feedback

Feedback usually occurs in the lowest octave of your instrument, generally around two notes
about a half step apart. Like blowing air across a bottle, the lower type of feedback (cavity
resonance) starts when the resonant air chamber inside your instrument is excited by the sound
pressure coming out of the speakers. We have found that it is effective to tune out an
instrument's cavity resonance feedback with the Anti Feedback (notch filter) in the Loudbox. For
acoustic guitar this occurs at G# on the low E-string, or at about 100Hz. Turn the Anti Feedback
knob to about 11:00 to dial out this resonance. Note that the circuit can be effectively defeated
by moving the dial to the OFF (7:00) position.
The higher range of feedback (top resonance) usually starts about a half or whole step above
cavity resonance of the instrument. Top resonance feedback happens when the resonant
frequency of the soundboard of your instrument is excited by the sound pressure coming off the
speakers. For acoustic guitar this occurs at A and above on the low E-string. Push the Phase
switch in and out until you find the position that subdues top resonance feedback.
Reverb
This is a classic spring style reverb that we have meticulously voiced
for acoustic instruments.
Mute
Silences the speaker and the XLR output for tuning or during breaks.
Engage the mute switch when you change instruments to avoid loud
electronic "pops". The LED next to the mute switch lights when the
mute is engaged.

Power Switch

Lower the Volume or engage the mute switch before you turn on the
amp to avoid surprise beginnings. Flip the power switch up and it
will light, indicating the amp is on.
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