A ducker gives even keyed rebalancing where a keyed compressor over-reduces loud notes

Keyed (side-chain) compression dips backing instruments in response to a lead, but it reduces most on the loudest lead notes and least on the quiet notes that most need help. A ducker — which opens when a gate would close — instead applies the same reduction for all key notes, which the author finds a better keyed rebalancing tool. Lacking a ducker, invert the polarity of a gated parallel send keyed from the lead to cancel the backing when the lead is present.

Examples

Ducking guitars from the lead vocal keeps a constant dip whenever the vocal plays, unlike keyed compression that barely ducks under the quietest, most vulnerable vocal notes.

Assessment

Explain why a ducker is preferred over keyed compression for rebalancing, and the polarity-inverted parallel-gate workaround.