A great trick for cleaning up drums has always been to insert a gate on the toms, kick, or snare. All too often gating is not enough to prevent a constant bleed of noise into these microphones from cymbals, hi hats, and the other drums. How about we set the gates to be triggered by the physical act of the drum stick striking the drum head instead of them being triggered sonically by the microphone.
The way we do this is by placing a small motion sensor on the drum head called a trigger. These are usually used for electronic drums but here we have a new purpose for them. When a drum head is struck the trigger sends a small electronic pulse down a wire. That electronic pulse is sent into the “key insert” or “side chain” input of the gate unit.
Many compressors and gates have a “side chain” or “key” input. The side chain is used to activate compression or gating from an outside source. Often used for “ducking” in film mixing, a compressor can be placed on a music track, but triggered by a voice over. By doing this the music can remain at a fairly loud level when there is no one speaking, but as soon as the voice is introduced to the mix the compressor will automatically compress the music allowing the voice to be heard more clearly.
But in our case we are taking an electronic pulse from a trigger and telling the gate to open and allow the microphone to be heard.
So here is the skinny.
1. Mic up the drum you will be gating and plug the microphone into a channel on your mixing console.
2. Place a trigger on the drum that you wish to gate.
3. Send that trigger signal to the “side chain” or “key” input on the gate unit.
4. Insert the gate into the mixing console channel that your drum microphone is in.
5. Set the gate threshold to a place where it is opening the way you like it.
With this kind of gating you could be launching cannons next to your microphones and the gates would not be opening, until you tap the drum.
Some time in the future I'll have a tutorial on how to make some triggers out of Radio Shack parts.........
