Compression Trainer

Threshold

"When does the compressor start working?" Below the threshold, audio passes through unchanged. Above it, the compressor reduces the level. Lower thresholds mean more of the signal gets compressed.

Ratio

"How much does it compress?" At 2:1, a signal 10 dB above threshold comes out only 5 dB above. At 4:1, it comes out 2.5 dB above. Higher ratios mean more aggressive compression. Above 10:1 is essentially limiting.

Attack

"What happens to the transient?" Fast attack catches the initial hit and smooths it out. Slow attack lets the transient punch through, then compresses the sustain. On a snare drum: fast attack kills the crack, slow attack preserves it.

Release

"How does it let go?" Fast release recovers quickly between hits, which can pump the level up audibly between transients. Slow release holds the gain reduction, creating a smoother but potentially "sat on" feel. Time the release to the music: the meter should return to zero just before the next downbeat.

Knee

"How does compression engage?" Hard knee (0 dB): compression snaps on at the threshold. The compressor is either working or it isn't. Soft knee (>10 dB): compression eases in gradually around the threshold, producing a more transparent, musical character. The difference is subtle and most audible on dynamic material like vocals or acoustic guitar.

Makeup Gain

"Compensating for what you lost." Compression reduces loud peaks, which lowers the overall level. Makeup gain brings it back up. Always level-match when comparing compressed vs. uncompressed, or your ears will prefer whichever is louder.