http://www.harmony-central.com/Effects/Data/Boss/CS_3_Compressor_Sustainer-01.html

Eða frekar:

“One popular use of compression is to increase an instrument's sustain. This is technically incorrect since a compressor doesn't change an instruments behavior, and it only operates on an audio signal. The compressor will try to maintain a constant level of output by amplifying the incoming signal to maintain that constant level. For example, after a string on a guitar is plucked, the voltage produced by the pickups gradually dies away. A little compression will keep the instrument's level from changing radically after it's plucked, which is perceived as increased sustain or a ‘smoothing’ of instrument. A release time longer than the instruments decay will preserve the instrument's sound.”

Eða til að þetta skiljist á Íslensku: Hann basicly þjappar hljóðinu og gerir þannig styrksmun á milli fast/laust minni/sama (eftir hvernig þú stillir hann. Svo magnar hann upp hljóðið (sem gerir hann að sustainer líka) eftir að það byrjar að lækka og lætur gítarinn hljóma lengur (sustain) See? Copy paste sucks!