About Acoustic Feedback - Fishman SoloAmp User Manual

About Acoustic Feedback

There are two features provided to help control acoustic feedback, the Phase
switch and the Anti-Feedback notch control.
Feedback usually occurs in the lowest octaves of your instrument. The natural
resonances which produce an instrument's tone also react with amplifi ed sound.
The louder an instrument is amplifi ed, the more it will interact. Feedback occurs
when a note on the instrument resonates in sync with the amplifi ed sound,
reinforcing and building to a sustained howl.
Phase Switch – The Phase switch fl ips the polarity of your instrument
signal from positive to negative, changing its relationship to the sound coming
from the amplifi er. One phase setting usually provides better resistance to
feedback than the other and will vary depending on the instrument and playing
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. When not using the Phase switch for feedback suppression, it is
recommended to leave it in the out (+) position.
The Phase switch also affects the signal polarity to the balanced D.I. and
Monitor outputs, synchronizing the amplifi er with other sound systems in use.
Anti-Feedback - The Anti-Feedback control is a variable frequency notch
fi lter designed to subdue a resonant peak on the instrument which is prone to
feedback. Turning the knob adjusts the center frequency of the fi lter, ranging
from subsonic (off) to 330Hz at full clockwise.
When not being used for feedback, the Anti-Feedback notch can also be used
as a tone control to subdue an unpleasant frequency in a microphone or room.
Play a note which accentuates the offending frequency and turn the control until
the intensity is diminished.
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