Gate / Expander

A gate is the opposite of a compressor. Where a compressor reduces signal above a threshold, a gate reduces signal below a threshold. When the input drops too quiet, the gate either turns it down by a fixed amount or silences it entirely.

An expander is a softer-knee gate. Instead of an on/off switch, it reduces level proportionally — quieter signals get reduced more gradually.

When to Use Them

Drum bleed. A close-mic on a snare picks up the kick, hi-hat, and toms too. A gate on the snare track silences it between hits, leaving only the snare itself.

Dialogue cleanup. Background noise (room hum, fans, traffic) sits at a low level between sentences. A gate or expander pulls it down without affecting the dialogue.

Removing low-level noise. Hiss, hum, breath sounds — anything that lives below the level of useful audio.

Key Controls

• Threshold — the level below which the gate kicks in.
• Range / Reduction — how much the gate attenuates signal below threshold (often −80 dB for full silence, or −20 dB for partial).
• Attack — how fast the gate opens when signal exceeds threshold.
• Hold — how long the gate stays open after the signal drops below threshold.
• Release — how fast the gate closes once hold time expires.

Setting Up a Drum Gate

A snare gate is the textbook use case:

1. Threshold just above the loudest hi-hat bleed in the snare mic — typically −30 to −40 dB.
2. Attack as fast as possible (sub-millisecond).
3. Hold long enough to let the snare's body through (50–100 ms).
4. Release to let the gate close gradually rather than chopping the tail (100–200 ms).
5. Range to whatever sounds natural. Full silence often sounds artificial — try −20 dB and see how it sits.

Side-Chain Triggering

Some gates let you key the gate from a different signal than the one being processed. This is useful for:

• Triggering a synth pad from a drum hit. Pad audio in, kick drum on the side-chain, threshold above the rest of the kit.
• Cleaning up overlapping mics. Drum room mic gated by the kick mic — only opens on kick hits.
• Effects gating. Reverb tail gated by the dry vocal — reverb only audible when the singer isn't.

Expander vs Gate

A gate is binary: open or closed. An expander is a ratio-based reducer below threshold (e.g., 4:1 expansion means a signal 1 dB below threshold gets reduced by 4 dB). The transition is smoother and almost always sounds more natural.

For dialogue cleanup or subtle drum tightening, an expander is usually the better choice. For hard snare-bleed elimination, a gate's harder action wins.

Common Mistakes

Threshold too high. The gate cuts off the natural decay of the source. Snares lose their tail, vocals get clipped at the start of words.

Attack too slow. The first transient of every drum hit is missed by the gate, making everything sound soft.

No release. A hard cut at the end of every hit creates an unnatural chop. Set release long enough to let the natural tail through.

Gating in the master chain. Gates are for individual tracks, not the whole mix. Gating the master cuts off ambience and reverb tails everyone has worked to build.

Plugin Recommendations

Further Reading

• FabFilter Pro-G Official Page