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Impulse creation

An easy way of impulse creation for convolution

What's convolution and impulse responses all about?

With a process called convolution you can "sample" the sound of an environment. This is done by sending an impulse into the environment and recording the result. By deconvolving this result, an impulse response (IR) is created. Using a convolver, IRs can be applied to any input material. When using a very special impulse called Dirac impulse (a single maximum spike), no deconvolving is necessary—this is an easy, but mostly not the best way for impulse creation!
The whole process can be used for real spaces and effect units as well.

What kind of FX can be captured?

Here we're talking only about some time invariant FX like Reverb and Delay. Dynamics, Pitch Shifter and modulation FX in general won't work. That means you can capture something, but when applied, the result sounds different than the original.

How do I create impulse responses?

  • Create a Dirac impulse. You can download (5 kb) which contains Dirac impulses in different wav formats. For convenience, file length is always half a second.
  • On the gear you want to capture, set predelay to 0 and dry/wet to 100 percent wet. Both parameters can be changed later when applying the IR.
  • Using the highest quality you have (digital connection), send the impulse to the gear to capture and record the result. Take care that there's no distortion on input and output.
  • You may normalize the IR and delete all silence at end and beginning. You can use Silence Remover to batch process many files at once.
  • Save, done, next impulse :)

What convolver supports which wav file format?

  • Samplitude 7: 16, 32 bit
  • Acoustic Mirror: 16, 24, 32 bit
  • SIR: 16, 24, 32 bit
  • There are many other convolution reverbs out there that I didn't test.

Links, a home for impulse responses
SIR, the freeware Super Impulse Reverb VST plugin for PC
Samplitude, the sequencer with build-in realtime convolution reverb and full latency compensation