Fishman AURA SPECTRUM DI User Manual page 13

Front Panel Controls (cont'd)
Anti-Feedback Footswitch
Use this search-and-destroy anti-feedback fi lter in addition to the phase
switch to control feedback during a performance. Aura Spectrum's
automatic anti-feedback fi lter can apply up to three separate notch
fi lters, which are essentially very precise tone controls that reduce only
a small piece of the audio band. When activated, the fi lter determines
where the offending resonances are and only reduces the frequencies on
which they are centered.
While the control is very effective, it's best if you spend
anti-feedback
some time while setting up before a performance and catch any issues
before you begin to play. With some practice, you'll fi nd you can also use
it to "fi x" any resonant notes that may stand out in a particular venue.
Using the automatic anti-feedback
1. Press and hold
anti-feedback
display will fl ash a " " to indicate it is searching for the fi rst feedback.
1
2. Turn up your volume , then either dampen the strings while tapping
the body or play the troublesome note until the feedback begins. The
fi lter will automatically identify and eliminate the feedback. The "
the display will light solid as will the "
3. At this point, you may continue to turn up your
to catch up to two more problematic resonances. Each is indicated via a
fl ashing " " or " " during the search, turning to solid lit numerals when
2 3
the resonance has been identifi ed.
4. You may tap the
anti-feedback
search. The circuit will hold the offending frequenc(ies) in memory until
you repeat the process again.
You may also turn the fi lter on or off at any time by tapping the foot-
switch. When enabled, the "
A-F
and the number of fi lters being applied will be briefl y displayed.
control:
footswitch for 2 seconds. The tuner
" indicator.
A-F
as in step 2
volume
footswitch at any time to cancel the
" lights to indicate the fi lters are active
24
About Phase and Anti-Feedback
There are two features provided to help control acoustic feedback, the
phase switch and the
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.
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.
The phase switch also affects the signal polarity to the balanced XLR
D.I. and 1/4 inch outputs, synchronizing the amplifi er with other sound
systems in use.
" in
1
In certain playing environments the phase switch may not have an
audible impact.
The
anti-feedback
ter designed to subdue a resonant peak on the instrument which is prone
to feedback. Check out page 24 for more exact details of its operation.
control.
anti-feedback
control is an automatic variable frequency notch fi l-
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