Hardware & signal path
Insert
An insert breaks a channel’s signal path so an external processor sits inside it — the whole signal goes out, through the device, and back. A send copies the signal; an insert replaces it.
In practice
A send copies the signal, an insert replaces it. Reverb wants a send; a compressor wants an insert.
Most DJ mixers offer sends and not inserts, which is why external processing in a booth is usually limited to effects rather than dynamics. Where an insert exists it is normally a single jack carrying both directions, so it needs a Y-cable rather than an ordinary lead — a detail that catches people out at exactly the moment they are trying to patch something in during a changeover.
Replaces
What an insert does
Copies
What a send does
Y-cable
What an insert jack needs
Where these come from: Standard mixer signal-path conventions — conventional design, not catalog figures. For what we can measure, see the copying version.
Why it matters
The distinction from a send is the whole reason both exist. Reverb and delay want a send, because you want the original signal plus some effect. A compressor or a filter wants an insert, because you want the processed signal instead of the original, not alongside it.
Getting it wrong produces a specific and confusing result: a compressor on a send gives you the uncompressed signal with a compressed copy layered on top, which sounds worse than either and defeats the point of the processor entirely.
Frequently asked
What is the difference between an insert and a send?+
A send copies the signal so you hear the original plus an effect; an insert replaces it so you hear only the processed version. Reverb wants a send, a compressor wants an insert.
Do DJ mixers have inserts?+
Most do not, which is why external processing in a booth is usually effects rather than dynamics. Where one exists it is often a single jack needing a Y-cable.
What happens if I put a compressor on a send?+
You get the uncompressed signal with a compressed copy on top, which sounds worse than either alone and defeats the purpose of the compressor.
Related terms
Send and return
A send takes a copy of a signal to an external effect; the return brings the processed version back into the mix. The original keeps playing, so the effect is added alongside rather than replacing it.
Signal chain
The signal chain is the ordered path a sound takes from file to room: player, mixer channel, master, amplifier, speaker. Each stage has its own level and can only pass on what the last one delivered.
Volume
Volume is how much of a signal leaves a stage — the fader. Gain is how much arrives at it. Every beginner conflates them, and the confusion produces a mix that is either quiet or distorted with no way back.
Compressor
A compressor reduces the level of anything above a threshold, narrowing the gap between the loud and quiet parts. The result can then be turned up as a whole, which is how records get their density.
Explore: LUFS meter · Send and return · Signal chain · All DJ terms