Drum triggers. What they are, and how they work.

A drum trigger is a microphone. Nothing more. It picks up the sound of the drum and sends the audio to the source. The source usually is an audio to midi converter either in the box or outside of the box, but that doesn't have to always be the case. The audio from a kick trigger, for example, can be sent to a side chain to trigger a ducking of the bass guitar. The audio from a tom trigger can be used to open a gate that adds a splash of extra reverb. They are merely microphones, and what you do with them is up to you.

To demonstrate this, I'll show you this video from Room Sound in which an SM57 was used to mic up a practice pad. The audio from the practice pad was converted into midi at some point in the signal chain, and that midi was used to trigger the Room Sound library. In this example, the SM57 was used as the drum trigger.



This is how applications like Slate Digital's "Trigger" work. They take the audio source, and apply a gate to it. When the transients open the gate, that tells "Trigger" to play the sample of the drum you've chosen. Depending on the intensity of the transient, "Trigger'" can decipher what the intended velocity would've been of the drum hit and play a sample that matches what the drum would've sounded like at that velocity.

A drum module, like my Roland TD-5, is nothing more than an audio-to-midi converter. If I were to plug in a bass guitar to the kick drum port on the TD-5, then smack the strings, it would generate an audio transient that would trigger a kick drum sound to be played in the drum module. The source of the audio transient doesn't have to be a trigger, it can be anything that can generate an audio transient and send that transient to an audio-to-midi converter of some kind. With this in mind, one could record a 5 piece drum kit with 5 mics to capture the kick, snare, and 3 toms. That audio could be routed out of the DAW into the respective input of the drum module, which would then treat the audio as a drum trigger and use the intensity of the transients to trigger velocity accurate drum samples from within the module. One could then record the midi output of the drum module, and use that midi profile to trigger a drum virtual instrument in their DAW such as Room Sound or Drum Forge.

Drum triggers are a pretty simple concept, but there's a lot of confusion about what they are and how they work. The important thing to remember is that they merely transmit an audio signal, which is exactly what your microphones are already doing. They may have different typical applications, but they are nothing more than microphones. Knowing this, try to find some creative new ways to use drum triggers or incorporate them into your productions!