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Owner's Manual
11
About Acoustic Feedback
Feedback usually occurs in the lowest octave of your instrument, gen-
erally with two notes about a half step apart. The lower type of feedback
(cavity resonance) starts when the sound pressure coming out of the
speakers excites the resonant air chamber inside your instrument. We
have found that it is effective to tune out an instrument’s cavity reso
-
nance feedback with the Anti-Feedback (notch filter) in the Loudbox
100. For acoustic guitar this occurs at G# on the low E-string, or at
about 100Hz. Turn the Anti-Feedback knob to about 11 o’clock to dial
out this resonance. Note that the circuit can be effectively defeated by
moving the dial to the OFF (7 o’clock) 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 sound pressure coming off the
speakers excites the resonant frequency of the soundboard of your
instrument. 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.
Phantom Power FAQs
Q: I have heard 24V phantom power can damage some audio devices. True?
A: Yes, phantom power can damage the following:
1. An unbalanced dynamic mic that has been modified for XLR.
2. A balanced line-level device that is not designed to accept phantom power (ex: some effects processors).
Contact the manufacturer to confirm compatibility.
3. Some older balanced wireless receivers can be damaged by phantom power. Consult the manufacturer of the
wireless unit for compatibility.
4. An instrument preamp or stompbox with an unbalanced output that is modified for XLR.
Important Note: Turn off phantom power if you plug any of the above into the XLR input.
Q: Which devices are safe with 24V phantom power?
A: All the following can be used safely with phantom power:
1. All balanced condenser microphones.
2. All balanced dynamic microphones.
3. Many new wireless units. Check with the manufacturer for compatibility.
4. A preamp/DI designed for phantom-power operation, such as the Fishman Pro-EQ Platinum.
Lower
Feedback Range
(E to G#)
Upper
Feedback Range
(A and above)
OFF
Anti
Feedback
Phase