Use parametric EQ on mic groups for feedback control — bypass filters until needed at soundcheck

The recommended method for managing vocal microphone feedback at live sound events is to insert parametric EQ filters on a dedicated vocal group bus, then bypass those filters until soundcheck reveals where feedback actually occurs. Parametric EQ allows targeting the exact feedback frequency with arbitrary bandwidth (Q), unlike a GEQ. During soundcheck, if gain-before-feedback is insufficient, the filters are enabled one by one until stability is achieved. Keeping the filters bypassed until needed preserves the frequency response of the vocal signal for most of the show, and avoids the spectral damage of always-on GEQ notches. The approach also accounts for the fact that mic and speaker positions may shift between soundcheck and performance.

Examples

Engineer sends all vocal mics to a ‘Vocals’ group. During line check, no filters are active. During soundcheck at show volume with monitors on, feedback appears at 3.1kHz — a parametric notch is set: freq=3.1kHz, Q=8, gain=-6dB, and enabled. The narrow notch handles the feedback without affecting the broader 2–4kHz region of the vocal.

Assessment

Compare the graphic-EQ feedback-notching method to the parametric-EQ-on-group method on three dimensions: frequency accuracy, collateral spectral damage, and adaptability to changing mic positions.