The automatic feedback controller shall be a single channel digital signal processor with nine 1/10- or 1/5-octave filters (selectable). It may be used on the whole mix, on sub-groups, or on selected insert points. The unit shall automatically sense feedback and determine its pitch, then assign a digital notch filter to the resonating frequency to automatically eliminate the feedback. The product shall use two types of user-selectable notch filters: «fixed» or «dynamic.» The fixed filters shall remain set on the initial feedback frequencies, while the dynamic filters shall be automatically reassigned new frequencies as feedback occurs during the program. The feedback controller shall include the following: an active/bypass button and LED indicator, which allow the user to set the unit to control feedback (active mode) or take the unit out of the signal path so it has no effect on the program (bypass mode); a clip level adjust, which controls system gain; clip LEDs, which indicate clip level and also indicate threshold level when enabling the selectable noise gate; a reset switch so all filters may be re-configured; a «lock fixed» button and LED indicator, which allows the user to lock fixed filters created during system set-up and to limit the total number of active filters; a row of filter stage activity LEDs to indicate active filters; and a two-position rocker-type power switch. Also provided is a jumper on the engine board for selecting 1/5- or 1/10-octave filters. The unit shall also be provided with an external power supply and 1/4″ TRS and XLR balanced and unbalanced input and output. The following performance criteria shall be met: Nine independent digital notch filters con-trolled automatically from 51Hz to 17,000Hz. Filter width: 1/10 or 1/5 octave (selectable), con-stant Q. Filter depth: DSP controlled, variable to -50dB. Resolution: 1/20 octave or better. Time required to find and eliminate feedback: 0.4 sec-onds, typical @ 1KHz. Total number of combined filters active: user selectable, from 1 to 9. Number of dynamic vs. fixed filters: user selectable. Last configuration stored in memory.
