dbx DriveRack VENU360 Loudspeaker Management System - Manual (Page 66)

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• CLEAR
Selecting this option then pressing the SELECT wheel triggers the clear function, which removes set AFS filters. The
clear function allows you to either clear only the Live filters or all AFS filters so you can ring out the system for a new
venue. The CLEAR MODE parameter selects which filters will be cleared when performing the clear function.
WARNING! If AFS is turned on and filters are set (in use), be careful when clearing AFS filters, as all filters will
be immediately removed from the signal path and sudden feedback could occur. It is recommended that you lower
your mixer output levels before clearing AFS filters.
• MODE [FIXED, LIVE]
This parameter determines whether the AFS algorithm will set Live or Fixed filters. Select the FIXED mode option to
initially ring out the system for optimal gain before feedback using the Fixed filters. Fixed filters are “static” and will
remain set until you manually clear them.
Once you have rung out the system with the Fixed filters, set the mode to LIVE to further protect the system from
feedback during the performance using the Live filters. In Live mode, AFS uses logic to determine what is feedback
and what is not. The enhanced AFS algorithm in the VENU360 can better distinguish between program material and
feedback, dramatically lowering the probability of false Live filters being set on feedback-like music content.
Live filters are “dynamic” and will update as feedback conditions change. When all of the Live filters have been set, they
will begin to round robin – meaning that if all Live filters have been set and new feedback occurs, the first Live filter set
will be released then re-set at the new feedback frequency location. The Live filters can be set to release after a period
of time by enabling the LIVE LIFT option and adjusting the LIFT AFTER parameter. Note that when you run the AFS
Wizard, AFS will automatically switch between Fixed and Live mode operation behind the scenes.
• TYPE [SPEECH, SPEECH/MUSIC, MUSIC]
This parameter sets the width and sensitivity of the AFS filters. The available options are:
SPEECH (Constant bandwidth of 11 Hz below 76 Hz, constant Q of 7 at or above 76 Hz)
This option is optimized for speech sound reinforcement, where wider notch filters are less noticeable. Select this
option when using the sound reinforcement system for speech only. With this option selected, notch filters will be
wider, but will provide the fastest, most solid protection against feedback.
SPEECH/MUSIC (Constant bandwidth of 9 Hz below 260 Hz, constant Q of 29 at or above 260 Hz)
This option is optimized for live music or speech sound reinforcement and provides the best all-around protection. It
will provide the best combination of fast feedback suppression and precision, using filters slightly narrower and less
audible than the SPEECH setting, but slightly faster than the MUSIC setting. If you’re not sure which setting to use,
select this option.
MUSIC (Constant bandwidth of 8 Hz below 927 Hz, constant Q of 116 at or above 927 Hz)
This option is optimized for live music sound reinforcement and offers the highest level of sonic quality. When this
option is selected, the AFS algorithm will zero in on the offending feedback frequency, while leaving the surrounding
frequencies unscathed. With this option selected, the AFS filters will take slightly longer to set than when using the
SPEECH/MUSIC setting, although the difference in time will be quite negligible.
NOTE: To guarantee that feedback is suppressed using the minimum number of filters possible, AFS may
automatically widen filters. For example, if you had selected the MUSIC setting and an adjacent frequency is feeding
back, AFS will detect both frequencies, and if they are in close enough proximity, will set a single, wider filter rather
than two narrow filters. Using a single, wider filter rather than two narrow filters will not alter the sonic quality and will
ensure that the maximum number of filters will always be available for use. Automatically adjusted filter widths will
never be any wider than the SPEECH setting.