Compression & Glue
Compressor (Peak/RMS/Expand, knee, lookahead), Glue Compressor on buses, Multiband Dynamics upward and downward, parallel and serial compression, limiter-as-compressor, and ratio/attack/release tables per source and genre.
Compression is automated gain riding with a reaction time measured in milliseconds. That's all it is, and it's why the three timing numbers (attack, release, and the hidden one: detector type) matter more than ratio. Live 12 ships three compressors that behave differently on purpose: Compressor is a clean, feed-forward, surgical tool with Peak/RMS/Expand modes; Glue Compressor is a feedback-topology bus compressor modelled on the SSL that smooths rather than grabs; Multiband Dynamics is three compressors/expanders with upward and downward action per band. This page is about choosing between them and setting the times by ear and by tempo.
Concept
A compressor measures level (the detector), compares it to a threshold, and turns the gain down by an amount set by the ratio, with the attack and release governing how fast the gain moves. Every audible characteristic falls out of that:
- Attack decides what happens to the transient. 0.01–1 ms clamps the transient (flatter, denser, duller). 10–30 ms lets the transient through and compresses the body: this increases perceived punch because the ratio of peak to sustain goes up.
- Release decides what happens to the tail and the groove. Short releases (20–60 ms) add density and distortion on low notes (the gain modulates within the waveform cycle: at 50 Hz one cycle is 20 ms). Long releases (300 ms+) make the compressor act like a slow level control.
- Detector: Peak responds to instantaneous level, RMS to average energy over a window; RMS hears more like the ear and lets transients through a feed-forward design on its own.
- Knee widens the region around the threshold where ratio ramps in gradually. A soft knee (6–12 dB) compresses a bit before the threshold and makes the onset of gain reduction inaudible.
- Lookahead delays the audio path so the detector sees the transient before it arrives. It gives a 0 ms-effective attack with no overshoot, at the cost of latency.
Techniques
Compressor modes: Peak, RMS, Expand
Compressor's three modes are three different devices. Peak for drums and anything with fast transients where you need predictable control. RMS for vocals, bass, buses, where average loudness is what you're levelling. Expand turns it into an expander or an upward compressor depending on ratio and threshold.
| Parameter | Value | Why |
|---|---|---|
| Peak mode | Drums, percussive synths | Reacts to each hit instantaneously; the attack is actually the attack |
| RMS mode | Bass, vocals, pads, buses | Averages over a window, transients pass, gain changes follow energy |
| Expand mode, ratio < 1 shown as 1:x, above threshold | Upward expansion | Boosts peaks: restore transients to an over-compressed loop |
| Expand mode, below threshold | Downward expansion | Soft gate: quiets room tone and reverb tails without chopping |
| Knee | 0 dB (drums) to 12 dB (vocals, bus) | Hard knee is audible as a grab; soft knee compresses earlier but gentler |
| Lookahead | 0 / 1 / 10 ms | 10 ms = full transient control for limiting-style tasks, adds 10 ms latency |
| Dry/Wet | 100% (serial) or 30–60% (parallel inline) | Compressor has a dry/wet; parallel without a rack |
Glue Compressor as a bus compressor
Glue is for making several sources sound like one. Stepped attack (0.01–30 ms) and release (0.1–1.2 s, plus Auto), ratios 2/4/10, a Range control that caps reduction, Soft Clip, and a Makeup gain. The feedback detector means it reacts to its own output, which rounds the onset of gain reduction and makes 1–3 dB of reduction sound like nothing happened except that the bus got tighter.
| Bus | Ratio | Attack | Release | GR | Note |
|---|---|---|---|---|---|
| Drum bus | 4 | 3–10 ms | 0.1–0.2 s | 2–5 dB | Attack lets kick/snare through, release pumps with the groove |
| Mix bus | 2 | 10–30 ms | Auto or 0.4 s | 1–3 dB | Only the loudest moments move the meter |
| Synth/chord bus | 4 | 1–3 ms | 0.2–0.4 s | 3–6 dB | Evens out stabs with different velocities |
| Vocal bus | 4 or 10 | 1 ms | Auto | 2–4 dB | After a serial Compressor on the vocal itself |
Multiband Dynamics: upward and downward per band
Three bands, each with an Above and a Below threshold. Above with a ratio greater than 1 is downward compression; Above with a ratio below 1 (shown e.g. 1 : 2) is upward expansion; Below with a ratio above 1 is downward expansion (gate); Below with a ratio below 1 is upward compression, which lifts quiet detail without touching peaks. The Amount knob scales the whole effect so you can dial it in and back off.
- Set crossovers: 120–200 Hz and 2–4 kHz are the usual splits. Solo each band to check what lives in it.
- Low band: downward compression (Above, ratio 2–4:1) with attack 10–20 ms and the global release long enough for the lowest note.
- Mid band: upward compression (Below threshold at −30 dB, ratio displayed below 1) to pull up room, decay and ghost notes. 2–4 dB is plenty.
- High band: fast downward compression to tame hat spikes, or expansion to add air.
- Use the Time control to scale attack/release across all bands and the per-band solo to hear each.
Parallel (New York) compression
Crush a copy, mix it under the original. The dry keeps transients; the crushed copy brings up body and room. The sum is louder and more exciting than either, with none of the dulling of serial heavy compression.
- Audio Effect Rack on the drum bus, two chains. Chain 1 empty (or a Utility). Chain 2: Compressor, Peak, ratio 10:1 or ∞, threshold very low, attack fastest, release 50–100 ms. Aim for 15–20 dB of reduction: it should sound ridiculous solo.
- High-pass the crush chain at 60–100 Hz so the sub doesn't get pumped, and maybe a shelf for air.
- Bring the crush chain up from −inf until the drums sound bigger, then back off 2 dB. Usually −12 to −6 dB.
- Map the chain volume to a macro: this becomes your "density" control for the drop.
Serial compression: two light stages beat one heavy one
Two compressors each doing 3 dB sound far more natural than one doing 6 dB, because each stage's attack and release can be specialised: a fast Peak stage catches the spikes, a slow RMS or Glue stage levels the phrase.
| Stage | Job | Typical |
|---|---|---|
| 1: Peak, fast | Catch plosives, string noise, 808 attack spikes | High ratio, fast attack, fast release, only 1–3 dB |
| 2: RMS, slow | Level the performance | Low ratio, slow attack, musical release, 3–5 dB |
| 3: Glue, bus | Blend with other sources | Ratio 2, Auto release, 1–2 dB |
Limiter as a compressor
Live's Limiter is a lookahead brickwall with a Release that can be set to Auto or 0.01 ms to over a second. With a slow release and a ceiling a few dB into the signal, it behaves as a very fast, very clean compressor with infinite ratio. On a kick or 808 this gives a dense, flat-topped tone without the waveshaper colour of clipping.
| Parameter | Value | Why |
|---|---|---|
| Gain | +3 to +9 dB | How hard you're pushing into the ceiling = the amount of "compression" |
| Release | 100–400 ms (not Auto) | Auto is tuned for transparency; a fixed slow release gives the compressor-like pump |
| Lookahead | 1.5–3 ms | Longer lookahead = softer, more compressor-like onset |
| Stereo link | L/R independent for mono sources, linked for buses | Unlinked limiting on stereo material shifts the image |
Transient-aware settings per source
Set attack by what you want to happen to the first 10 ms, release by the tempo and the lowest frequency. The envelopes below show the two basic shapes: the "let it through" compressor that increases punch and the "clamp it" compressor that increases density.
| Source | Mode | Ratio | Attack | Release | GR | Goal |
|---|---|---|---|---|---|---|
| Kick | Peak | 4:1 | 10–30 ms | 80–150 ms | 3–6 dB | More click, controlled tail |
| Snare / clap | Peak | 4–6:1 | 5–15 ms | 60–120 ms | 4–8 dB | Crack through, body evened |
| Hats / tops | Peak | 3:1 | 0.5–2 ms | 30–60 ms | 2–4 dB | Tame spikes, or skip entirely |
| Sub bass | RMS | 3:1 | 30 ms | 150–300 ms | 2–4 dB | Level notes, never pump |
| Reese / mid bass | RMS | 4:1 | 10 ms | 100 ms | 4–6 dB | Constant harmonic density |
| Vocal | RMS | 3–4:1 | 5–20 ms | Auto / 150 ms | 3–6 dB | Intelligibility, not thickness |
| Pad | RMS | 2:1 | 30 ms | 500 ms+ | 2–3 dB | Almost invisible leveling |
| Pluck / stab | Peak | 4:1 | 3–8 ms | Tempo (1/16) | 4–8 dB | Even velocities, keep snap |
| Sampled break | Peak | 6:1 | 1–5 ms | 40–80 ms | 6–12 dB | Classic smashed break; parallel if too much |
Drum bus vs mix bus: different goals, different compressors
The drum bus wants energy: a Glue at 4:1 doing 3–5 dB with a release that pumps on the beat, maybe Drum Buss with Drive after it. The mix bus wants cohesion with no audible movement: Glue at 2:1, 1–2 dB, Auto release, Range capped, and the knowledge that the limiter later will do the actual loudness work.
| Aspect | Drum bus | Mix bus |
|---|---|---|
| Device | Glue or Compressor Peak | Glue only (or none) |
| Ratio | 4 | 2 |
| Attack | 3–10 ms | 10–30 ms |
| Release | 0.1–0.2 s (tempo) | Auto, or 0.3–0.6 s |
| GR | 3–6 dB | 1–2 dB |
| Sidechain EQ | HP 60 Hz so the kick doesn't drive everything | HP 100 Hz: bass shouldn't drive the mix bus |
| Soft Clip | Yes | Rarely |
Internal sidechain EQ: compress what you hear, not what the meter sees
Each of Live's compressors has a sidechain EQ that works even without an external key. High-passing the detector at 80–150 Hz stops the sub from driving the gain, so the compressor levels the mids and highs and the low end stays steady. A bell boost in the detector at 2–5 kHz makes the compressor react more to harshness (a de-esser-lite on a vocal, a hat-tamer on a drum loop).
| Detector EQ | Use |
|---|---|
| HP 80–150 Hz | Bass, drum bus, mix bus: sub stops pumping the mids |
| Bell +6 dB at 3–6 kHz, Q 1 | Vocals: compressor grabs sibilance and harsh consonants harder |
| LP 200 Hz | Kick-only trigger on a mixed drum loop |
| Bell −12 dB at kick fundamental | Drum bus compressor ignores the kick, levels snare and hats |
Compression macros for performance
For a live set, the compression you reach for in a drop is a macro: one knob that lowers the threshold of a Compressor while raising its output and raising the NY chain. Map all three with ranges that cross-fade sensibly, then use Macro Variations to store "verse", "build", "drop" states.
Settings per source / genre
| Genre | Drum bus | Bass | Mix bus | Character |
|---|---|---|---|---|
| Deep house | Glue 4, 10 ms, 0.2 s, 2–3 dB | RMS 3:1, 30 ms, 200 ms | Glue 2, 30 ms, Auto, 1 dB | Round, no visible movement |
| Tech house | Glue 4, 3 ms, 0.1 s, 4–5 dB + Drum Buss | Peak 4:1, 10 ms, 100 ms | Glue 2, 10 ms, 0.3 s, 2 dB | Tight, punchy, dry |
| Techno (hard) | Compressor Peak 6:1, 1 ms, 60 ms, 6–10 dB + NY | Limiter as comp | Glue 4, 1 ms, 0.1 s, 3 dB, Soft Clip | Dense, pumping, saturated |
| Dubstep / 140 | Glue 4, 10 ms, 0.2 s + parallel | Multiband: low 3:1 slow, mid 4:1 fast | Glue 2, Auto, 1–2 dB | Big drums, controlled growls |
| DnB / jungle | Peak 6:1, 3 ms, 50 ms, 6 dB on breaks + NY heavy | RMS 4:1 on reese, Limiter on sub | Glue 2, 10 ms, 0.2 s | Smashed breaks, surgical sub |
| Trap / drill | Light: Glue 2, 3 dB | 808: Limiter + Saturator, no compressor | Glue 2, Auto, 1 dB | 808 untouched, hats dry |
| Lo-fi / boom bap | Peak 8:1, 1 ms, 40 ms, 8–12 dB (serial, on the loop) | RMS 4:1, 20 ms | Glue 4, 1 ms, 0.1 s, 4 dB | Everything audibly squashed; that's the point |
| Ambient | None or Glue 2, 1 dB | None | Glue 2, 30 ms, 1.2 s, 1 dB | Dynamics preserved |
| Dub techno | Glue 4, 10 ms, 0.4 s, 3 dB | RMS 3:1, 30 ms | Glue 2, Auto, 2 dB + Multiband upward on mids | Chords breathe with the kick |
Common mistakes
- Fast attack on everything. You clamp the transients and then wonder why the mix has no punch. Start at 10 ms and go faster only with a reason.
- Release faster than the lowest frequency's period. 20 ms release on a 40 Hz sub (25 ms per cycle) is a distortion box. Minimum release on bass: 100 ms.
- Judging with the makeup gain mismatched. Louder sounds better. Match the output level before deciding whether the compression helped (Compressor's Dry/Wet at 0% with matched gain, or A/B compare in 12.3).
- One compressor doing 10 dB. Split it into serial stages or parallel.
- Lookahead on a track inside a sidechain relationship adds latency that Live compensates on the audio path but not on the key, shifting the duck.
- Compressing a sub with a compressor instead of a limiter or saturator. The sub's dynamics are the notes; you want them flat, so flatten them.
- Mix-bus Glue added last. Insert it before you mix, set 1–2 dB, and leave it.