dbx DriveRack User Manual page 17

DriveRack
• Press the <NEXT PG> button and the display will read:
• Once the gain level of the mixer has been turned down, press the <NEXT PG> but-
ton and the display will read:
• You will now use the <DATA> wheel to select the number of fixed filters. This will
range from values 0-12. The total number of filters will stay at 12, and the number of
live filters will be = Total Num Filters – Num Fixed. Live and Fixed filter types differ
in that FIXED mode filters are automatically assigned to a frequency creating feedback,
thus remaining at that frequency until cleared by the user. In LIVE mode, live filters
automatically detect and remove feedback frequencies in the presence of audio (music
or speech). When all of the live filters have been used, they begin to round robin.
Essentially this means that the first filter set is replaced where a new feedback is detect-
ed and notched out. This mode is useful because feedback frequencies may change
as the microphone is moved, and/or as the characteristics of the venue change.
The Fixed/Live filter usage will be indicated at the bottom of each page of the feed-
back elimination effect. 'F' indicates an available fixed filter, and 'L' indicates an avail-
able live filter. A blocked out F or L indicates a filter that is set, or in use. Once the
desired number has been selected, press the <NEXT PG> and the display will read:
• These types pertain to the Q, sensitivity, and algorithm type. The filter is established
by using the formula: Q= Freq divided by Bandwidth. This means that a higher Q
will produce a filter that is more narrow. Values are: Speech (Bandwidth = 1/5
octave and Q=7.25) Music Low (Narrow notch filter, Bandwidth = 1/10 octave and
Q=14.5), Music Medium (Very Narrow notch filter, Bandwidth = 1/20 octave and
Q=29) Music High (Ultra Narrow notch filter, Bandwidth = 1/80 octave and Q=116).
To guarantee that feedback is suppressed at lower frequencies, the AFS may place
wider notch filters at these lower frequencies (below 700 Hz). Once the desired fixed
®
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PA
DriveRack PA WIZARD
System Setup
Auto EQ WIZARD
AFS WIZARD
AFS
Please turn down the
mixer gain. Press
NEXT PG when done.
AFS
Select Number of
fixed filters. > 6
F F F F F F L L L L L L
AFS
Select fixed type
> Speech
Getting Started
DriveRack™ PA User Manual
Section 1
9