Hardware & signal path
Feedback
Feedback is a loop: a microphone hears a speaker playing what the microphone just heard, and the loop builds until one frequency dominates and howls. It needs an open mic and a speaker the mic can hear.
In practice
Feedback needs an open mic and a speaker it can hear. Remove either one and it stops immediately.
When it starts, drop the mic gain rather than the master — the master takes the music down with it and the loop is still armed. Then move: a step out of the monitor’s cone is often enough. If a booth howls reliably at one pitch, cut narrowly there on the mic channel rather than broadly everywhere, and you keep the intelligibility you would otherwise lose. Never point a microphone at a monitor to check whether it is on.
Mic gain
The control that stops it
One step
Out of the monitor’s throw
Narrow cut
The fix for a room that rings
Where these come from: Standard feedback control practice from live sound — established technique, not catalog figures. For what we can measure, see setting the mic in the first place.
Why it matters
In a DJ booth it is almost always the microphone and almost always avoidable, because the two ingredients are both under your control. Gain down when the mic is not in use, and stand out of the monitor’s throw when it is, and it simply does not happen.
The frequency it picks is not random — it is wherever the room, the mic and the speaker together have the most gain, which is why the same booth howls at the same pitch every time. Knowing that turns a panic into a single EQ move.
Frequently asked
How do I stop feedback quickly?+
Pull the microphone gain down, not the master. The master reduces the music too and leaves the loop ready to start again the moment the level comes back.
Why does it always howl at the same pitch?+
Because the loop starts wherever the room, the microphone and the speaker together have the most gain, and that combination does not change between sets in the same booth.
Can a DJ setup feed back without a microphone?+
Rarely — the usual culprits are a mic or a turntable cartridge picking up bass through the plinth, which is a related loop and is fixed by isolating the deck rather than by EQ.
Related terms
Mic input
A mic input takes the very low signal a microphone produces and amplifies it to line level, with its own gain, usually its own two-band EQ, and on club mixers a talkover control that ducks the music while someone speaks.
Booth monitor
The booth monitor is the speaker pointed at the DJ, fed from its own output with its own level control. It is separate from the master, so turning it up changes what you hear and nothing the room hears.
DJ booth
The DJ booth is the space the equipment sits in: the table, the monitor, the power, and where all of it sits relative to the floor. It is part of the instrument, because it decides what you can hear.
Club sound system
A club sound system is the whole chain after the mixer: processor, amplifiers, subwoofers, main speakers and often delay or fill speakers, tuned together for one room by an engineer who is not in the booth.
Explore: Frequency detector · Mic input · Booth monitor · All DJ terms