'Ringing out' a monitor system identifies feedback frequencies with EQ to maximize gain before feedback

‘Ringing out’ is the process of tuning the equalization of a stage monitor system before the performance to suppress resonances that cause feedback. The procedure: gradually increase monitor gain until the system begins to ring (a slight resonance or tone just below full feedback); identify the frequency using an RTA or by ear; apply a narrow EQ cut (graphic or parametric) at that frequency; increase gain until the next feedback frequency appears; repeat. By suppressing multiple feedback peaks, the overall system gain can be increased 6–10 dB above its initial feedback threshold. 1/3-octave graphic EQ is most commonly used because it provides narrow enough cuts to notch feedback frequencies without significantly affecting adjacent program material.

Examples

A monitor engineer slowly raises the gain before soundcheck. At 2 kHz a ring appears — they apply a –6 dB notch at 2 kHz on the graphic EQ. At 800 Hz a ring appears — another notch. After 5 iterations, they have 10 dB more gain available than at the start.

Assessment

Why is equalization performed at the amplifier input (or master insert) rather than on individual input channels during ring-out? What instrument is used to identify the feedback frequency precisely?