What is Sidechain compression?
Sidechain compression is a technique where a compressor on one sound is triggered by a different sound — most commonly ducking the bass every time the kick hits — creating both a cleaner low end and the rhythmic "pumping" feel central to techno and house.
Route the kick to the sidechain input of a compressor placed on the bass (or rumble, pads and atmosphere). Every kick hit pushes the target down by a few dB, then it swells back — the release time shapes the groove: fast release is transparent, slow release pumps audibly. Many producers now use volume-shaper/LFO tools instead of a real compressor for surgical control of the ducking curve. In techno, sidechain is both corrective (kick clarity) and aesthetic (the breathing motion of the whole track).