FOH / Mons Mixing / Monitor Feedback Control: Mic Technique, Polarity & Wedge Placement

Monitor Feedback Control Mic, Polarity & Placement

Three practical tools for fighting monitor feedback that sit alongside ringing out the system: how a directional mic is actually held on stage, when flipping polarity helps, and how a pair of wedges should be placed relative to each other. Reference: SRH-MON-FEEDBACK-01.

Key facts: covering a handheld mic's rear vents or cupping the grille collapses its directional pattern and makes feedback worse, not better; try a polarity flip at the monitor speaker before ever touching the mic's polarity; and a pair of wedges belongs close together with their rear corners touching and splayed outward — never aimed to cross paths out in front of the performer.

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Handling Directional Mics on Stage

Keep the mic's rejection side — usually the rear of a cardioid capsule — pointed at the nearest wedge. That's the entire reason a directional mic buys extra gain before feedback in the first place. Don't let a hand or grip cover the small ports/vents near the rear of the capsule or down in the handle — blocking them collapses the mic's polar pattern back toward omnidirectional and quietly kills the feedback rejection you were relying on. Watch for performers "eating" the mic — cupping a hand fully over the grille or swallowing the head does the same damage as covering the vents, even though it looks like a stylistic choice rather than a technical mistake. Brief performers tactfully on correct mic-holding technique before showtime — it's a habit worth correcting early rather than fighting feedback from it all night.

Flipping Polarity to Fight Feedback

Treat a polarity flip as an extra tool once ringing out and good mic technique aren't buying enough headroom on their own. Flip polarity at the monitor speaker or output first — via a console polarity switch, or by swapping the two wires at the amp/speaker end — rather than at the mic. Avoid flipping polarity at the mic itself where you can help it: it can skew the stereo image on a stereo mix, break mono compatibility for any recording or broadcast feed, and complicate blending that mic with others later. Understand why it helps: flipping polarity puts the reinforced (monitor) wavefront out of step with the direct sound arriving at the mic, so the two partially cancel instead of stacking up toward feedback. After any polarity change, sanity-check mono compatibility by soloing/cueing the affected inputs together — if the combined signal noticeably drops in level rather than staying solid, something in the chain is out of phase.

Placing a Pair of Monitor Wedges

A single wedge is straightforward: aim it so the performer actually stands inside its coverage, keep it close given how loud things get onstage, and lean on the manufacturer's dispersion data for the high frequencies that matter most for intelligibility — then fine-tune the aim by ear against recorded music. It also helps to keep the wedge sitting in the mic's rejection zone rather than its hot side, since that's free extra gain before feedback for no added cost.

Two wedges for one roaming vocalist is where it's easy to get wrong. The instinctive layout — one wedge on each side of the performer's range, angled inward so their coverage patterns cross out in front — actually works against you: where those two patterns overlap, the two speakers interfere with each other and create comb filtering, which shows up as an uneven, holey frequency response and a lower ceiling before feedback. The better layout is to push the pair close together with their rear corners touching, then splay them outward to cover the performer's full range. That keeps each wedge covering its own zone cleanly instead of fighting the other one in the middle, which gives smoother coverage and noticeably more headroom before things ring.

Source: Davis, Gary D. & Jones, Ralph. The Sound Reinforcement Handbook, 2nd ed. (Hal Leonard/Yamaha). Sections 11.11.1, 11.11.2 & 11.11.4, pp.186-187, 189. Rewritten in Ryan's own words from the source material.