TC-Helicon Play Acoustic - Reference Manual - Manual (Page 58)

Guitar FX button/section
Play Acoustic – Reference manual (2014-07-16) 56
Guitar Anti-Feedback page (7/7)
In live environments, the open body style of
acoustic guitars is especially prone to feedback
from nearby sound sources such as stage moni-
tors or PA speakers. To assist you with feedback
management, there are some controls to ad-
dress the most common feedback culprits.
Phase Invert parameter
Use the Phase Invert parameter to invert the
phase of the guitar signal by 180°.
This can help prevent feedback when playing
your acoustic guitar close to a stage monitor or
other speaker. When you experience feedback,
this should be the first setting to try.
Low Cut Filter parameter
Acoustic guitars can be prone to resonance, es-
pecially in the low frequency range. If you are
having trouble with “rumbling” or low frequency
feedback, use the Low Cut Filter parameter to
roll off low end frequency from your guitar signal.
Notch Filter section
This very narrow band equalizer can help “hone
in” on feedback-causing frequencies and reduce
their gain.
Notch Gain parameter
Use the Gain parameter to set the gain for the
note/frequency range you have selected with the
Freq parameter. Use negative values (e.g. -8) to
reduce troublesome frequencies.
If you are unsure which frequency is causing the
feedback, it can be useful to use positive values
(8 for example) to boost the feedback you are
hearing. This allows you to highlight problematic
frequency ranges more easily. Then, you can re-
duce the Gain setting for this frequency range
using a negative value.
Notch Freq parameter
Use the Freq parameter to set the frequency of
the notch filter. For this parameter, we show both
the frequency in Hz and the relative note (A# for
example). The frequency parameter can be ad-
justed in 25 Cent increments from note to note.
Often, you can determine the note that’s feed-
ing back by simply playing a chord and “feeling”
which string vibrates unusually under your finger.
After you have selected that particular string/
note using the Freq parameter, you can use the
Gain parameter to reduce feedback for that note.
Simple steps for
feedback reduction
► Set the Phase Invert parameter to “On”. If this
doesn’t eliminate the feedback, try the follow-
ing steps.
► Change the Gain parameter to a high positive
setting such as 8 or more.
► Use the Freq parameter to “sweep” through
frequencies until the feedback gets “a lot
worse” as you move past it with the Freq con-
trol.
► Once you have found the troublesome fre-
quency, change the Gain parameter to a nega-
tive setting until the feedback disappears.
► Lastly, if you still get feedback, turn your guitar
level down in the Mix section described next.