Audio, from zero Boring Solutions
Level 0 · Lesson 0.4

Getting a mic loud enough without the squeal

After this you can bring a mic up loud and clear in the room without it ringing or squealing.

First Sunday at the Board 7 min read

The hook

The pastor clips on the lav, walks to center stage, and starts talking. You can barely hear him in the back, so you reach for the one knob you remember and push it up.

For a second it's better. Then the room finds a note and holds it. A thin, rising squeal climbs over the sermon, every head turns toward the booth, and your hand freezes on the board.

You didn't break anything. You just hit feedback, and there's a calm order of moves that keeps it from happening. Once you know the order, a loud mic stops being a gamble.

Video coming soon

The lesson

Two controls set how loud a mic gets, and they do different jobs. Get them in the right order and the squeal mostly takes care of itself.

The gain (some boards call it trim) sets how hard the mic's own signal hits the channel. It's the first knob in the chain. The fader is the long slider that sets how much of that channel goes out to the room.

Here's the safe order, every time:

  1. Fader to unity first. That's the 0 mark — on most boards it sits about three-quarters up the slider's travel. This is the fader's honest, natural spot. Park it there before you touch anything else.
  2. Bring the gain up while they talk. Ask the person to speak at their normal level, the way they'll actually deliver. Slowly raise the gain until the channel meter is sitting healthy. You want it living in the green with the loudest words tickling yellow, not pinned at the top, not buried at the bottom.
  3. Now use the fader for room volume. The channel is set. If it needs to be louder in the seats, push the fader up from 0. Go only as far as it stays clean.

That's it. Gain sets the channel's strength. Fader sets how much the room hears. Most "too quiet" problems are a gain that was never set, not a fader that wasn't pushed far enough.

When a mic does start to ring, you don't need to diagnose it in the moment. Pull the fader down. Bringing that channel down breaks the loop instantly and quietly. Once it's calm, set it back up more carefully, or leave a little more room under it.

A few habits keep you well clear of the edge:

  • Mic close to the mouth. This is the biggest lever you have. Close means more voice for less gain.
  • Point speakers away from open mics. A main speaker firing back into a mic is feedback waiting to happen. Mics should be behind or to the side of where the PA throws.
  • Don't chase a quiet talker with gain. Move the mic, coach the person, but don't keep cranking.
  • Trust the bloom. The moment it starts to ring, fader down. You can always bring it back.

A small EQ cut on the exact note that rings will buy you more level later, and you'll learn that in Level 4. For a first Sunday you don't need it. The order of operations and a close mic will carry you.

Go deeperoptional

A feedback loop squeals when two things are true at once: the sound arriving back at the mic is as loud as the sound that started it (loop gain reaches 1), and it comes back in phase so the round trips stack up instead of cancelling. Miss either condition and it can't run away. That's why it always locks onto a specific frequency: it's whichever note the room, the speakers, and the mic conspire to keep both loud and in phase.

The practical version of this is gain-before-feedback, the headroom between your working level and the point where the room takes off. A well-set system can usually be pushed to within about 6 dB of feedback before you hear ringing. Everything in this lesson is about widening that margin so your normal mix sits comfortably inside it.

Proximity is the cheapest margin you can buy, and the reason is the inverse-square law: sound pressure roughly halves with each doubling of distance, so halving the mic-to-mouth distance is worth about +6 dB of voice with no extra gain. A mic at two inches versus four inches is a real, free 6 dB of signal that the speakers never get. That's gain-before-feedback you didn't have to fight the room for.

Remember

  • Two controls, two jobs: gain sets the channel's strength, the fader sets how loud the room hears it.
  • Set them in order: fader to 0, gain up while they talk until the meter's healthy, then fader for room volume.
  • Feedback is a loop: the mic hears the speakers, and it runs away on one note.
  • Pull the fader to kill a ring. Instant, quiet, undoable.
  • Get the mic close before you reach for more gain. Distance is free level.

Your turn

  • On a real mic, set the fader to 0, then bring the gain up while someone talks normally until the meter sits in the green tickling yellow.
  • Push the fader up slowly until you hear the first hint of a ring, then back it off until it's clean. That spot is your ceiling for this mic today.
  • Have the talker hold the mic close, then a foot away, and watch how much gain each needs.
  • Practice the kill move once on purpose: when it rings, pull the fader down without panic.