Further Details On The Anti Feedback Function; How The Removal Of Feedback Is Achieved; About The Safety Margin - Roland CPM-300 Owner's Manual

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Further Details on the Anti-Feedback Function

The CPM-300's Anti-Feedback function works by applying narrow-band "filters," called "Anti-Feedback Filters," to

the frequencies at which feedback is generated, thus eliminating the feedback by reducing the volume of those fre-

quencies. The CPM-300's Anti-Feedback function features eight separate filters.

With the "Auto Adjust Function," the volume is gradually raised, the intention being to actually cause feedback. It

detects the frequencies where feedback occurs, and after the Anti-Feedback Filter settings are finished, the gain is

returned to the original level. When the Auto Adjust procedure is finished, margin of gain (called the "safety mar-

gin") is maintained, so it keeps working even if conditions change. Six Anti-Feedback Filters are assigned in the

Auto Adjust Function.

The "Dynamic Adjust Function," which operates continuously whenever the Anti-Feedback ON/OFF switch is set

to ON (except when Auto Adjust is in progress). It monitors the sound for feedback during performances, and elim-

inates any feedback that may suddenly occur. Two Anti-Feedback Filters are used with the Dynamic Adjust func-

tion.

The bandwidth of these eight Anti-Feedback Filters is extremely narrow, so they can suppress feedback while hav-

ing very little effect on the sound quality.

At the completion of Auto Adjust, a "safety margin" of approximately 12 dB will have been set up. However, during

the Auto Adjust procedure, the Auto indicator will begin to flash rapidly as soon as a safety margin of 6 dB has

been achieved. This conveniently allows you to stop Auto Adjust while it is in progress, if you believe that a 6 dB

margin is sufficient for your needs.

*Auto Adjust ends when all six Anti-Feedback filters are set, even if the approximately 12 dB for the safety margin

is not attained.

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