Roland CPM-300 Owner's Manual page 14

Eliminating Feedback (Anti-Feedback Function)
Awful, ear-splitting whines and screeching sounds referred to as "feedback" occur when the output from the speak-
ers reenters the microphone, when it is further amplified and then output again, over and over, creating a feedback
loop which results in these unpleasant oscillations in the sound. Feedback crops up readily when the mic volume is
set too high, or when the mic is pointed at or placed too closed to a speaker.
How to Avoid Feedback
The following describes measures you can take to help prevent feedback from becoming a problem.
@Select the proper output level for the particular room or venue.
@Separate mics and speakers as much as possible, and avoid pointing mics in the direction of the speakers
@Set the volume levels of connected instruments at appropriate levels.
In actuality, however, feedback may still occur even though you've observed the preventive measures listed above.
Using the CPM-300's Anti-Feedback Function
The CPM-300's built-in "Anti-Feedback Function" is a function that automatically detects feedback the instant it
begins, after which the Anti-Feedback Filters then eliminate the feedback. The Anti-Feedback Function feature
includes two functions.
@Auto Adjust Function
You can eliminate feedback before your performances by running the Auto Adjust Function during your sound
check or rehearsal.
@Dynamic Adjust Function
This function monitors and instantly cuts unexpected feedback during performances.
Procedure for Operating the Auto Adjust Function
ON/OFF Indicator
ia | ON/OFF Switch
AUTO SET Indicator e
AUTO SET Switch
1.Set up microphones at the positions they will be used, then switch them on.
2.Switch the ON/OFF switch to ON.
3.Ready the mixer by raising the faders on channels to which microphones or other inputs are connected, and the
MASTER fader to appropriate levels.
4.Hold down the AUTO SET switch for at least two seconds.
The AUTO SET indicator flashes, and while feedback is generated, the point at which the feedback starts is automat-
ically detected, and the feedback is eliminated.
5.The setting is fixed when the AUTO SET indicator changes to steady illumination.
When Quitting Auto Adjust Function During the Procedure
Press the AUTO SET switch. The AUTO SET indicator is illuminated, and the Anti-Feedback Filter settings in effect
at that time are stored and retained.
Resetting the Auto Adjust Function from the Beginning
Hold down the AUTO SET switch for at least two seconds. The Anti-Feedback Filter settings in effect up to that time
are cleared, and determination of the point at which the feedback starts is begun again.
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