Find the core

Begin with a source that carries the identity of the impact. Add a lower layer for body and a short, brighter source for the attack. Keep the fourth layer for debris, resonance or space.

Make the layers agree

Adjust pitch, gain and timing while listening to the combined result. Use peak alignment when the layers should arrive together, and audition it against their natural timing.

Create a family of hits

Keep the core layer stable while varying texture and detail. Capture several results and compare them at similar loudness before choosing the final set.