PRESSURE Control
The PRESSURE knob is the heart of the plugin. It simultaneously maps threshold, ratio, attack, release, and knee width using per-engine quadratic curves — one knob does the work of five parameters.
How It Works
PRESSURE uses a p² (quadratic) curve to map the 0–100% knob position to compression parameters. The quadratic scaling means the knob feels linear to your ears: small movements at the bottom make subtle changes, while the top of the range gets progressively more aggressive.
Each engine defines its own curve, so the same PRESSURE position produces different behavior depending on the selected mode. The tables below show exact values at P=0.0 (minimum), P=0.5 (midpoint), and P=1.0 (maximum).
AUTO Mode
When AUTO is enabled, attack and release are program-dependent — they adapt to the incoming signal rather than using fixed values. The PRESSURE knob still controls the target amount of gain reduction, but the timing parameters adjust automatically to match the material.
TONE Interaction
The TONE knob tilts the sidechain detection frequency. On VCA, Drums, and VariMu engines, it controls a sidechain high-pass filter using a tone² curve:
| Engine | SC HPF Range | Notes |
|---|---|---|
| VCA (MIX) | 20–300 Hz | tone² × 150 Hz, enabled when tone² > 0.01 |
| FET (INST) | — | No sidechain HPF |
| Opto (VOCALS) | — | Controls emphasis (optical cell emphasis) |
| Dynamics (DRUMS) | 20–120 Hz | tone² × 120 Hz, protects kick drum |
| VariMu (MASTER) | 20–250 Hz | tone² × 120 Hz |
VCA (MIX Mode)
SSL G-Bus character
| PRESSURE | Threshold | Ratio | Attack | Release | Knee |
|---|---|---|---|---|---|
| 0% | -14 dB | 2.0:1 | 30.0 ms | 1200 ms | 12 dB |
| 50% | -28 dB | 4.5:1 | 15.5 ms | 650 ms | 7.5 dB |
| 100% | -42 dB | 8.0:1 | 1.0 ms | 100 ms | 3 dB |
Knee width scales inversely with ratio — SSL's defining trait.
FET (INST Mode)
1176 “Dr. Pepper” character
| PRESSURE | Threshold | Ratio | Attack | Release | Knee |
|---|---|---|---|---|---|
| 0% | +22 dB | 4.0:1 | 800 μs | 50 ms | 6 dB |
| 50% | -6.5 dB | 4.0:1 | 410 μs | 150 ms | 6 dB |
| 100% | -35 dB | 21.0:1 | 20 μs | 50 ms | 6 dB |
Ratio steps at P=60%→8:1, P=80%→12:1, P=92%→20:1, P=97%→All Buttons In (21:1). Release follows a V-shaped curve peaking at P=50%.
Opto (VOCALS Mode)
LA-2A optical character
| PRESSURE | Threshold | Ratio | Peak Reduction | Mode |
|---|---|---|---|---|
| 0% | 0 dB | 2.0:1 | 0 | Compress |
| 50% | -36 dB | 7.0:1 | 30 | Compress |
| 100% | -72 dB | 12.0:1 | 60 | Compress/Limit |
Ratio is continuously variable (not stepped) — models the LA-2A's optical cell where compression ratio increases with signal level. No sidechain HPF; TONE controls emphasis instead.
Dynamics (DRUMS Mode)
dbx 160 transparent character
| PRESSURE | Threshold | Ratio | Attack | Release | Knee |
|---|---|---|---|---|---|
| 0% | -8 dB | 2.0:1 | 30.0 ms | 300 ms | 0 dB (hard) |
| 50% | -20 dB | 3.5:1 | 16.5 ms | 200 ms | 0 dB (hard) |
| 100% | -32 dB | 8.0:1 | 3.0 ms | 100 ms | 0 dB (hard) |
Hard knee always enforced (dbx 160 defining trait). Slightly slower attack than VCA preserves drum transients.
VariMu (MASTER Mode)
Fairchild 670 tube character
| PRESSURE | Threshold | Ratio | Attack | Release | Knee |
|---|---|---|---|---|---|
| 0% | -24 dB | 2.0:1 | 0.4 ms | 5000 ms | 15 dB |
| 50% | -34 dB | 4.0:1 | 0.325 ms | 2650 ms | 11.5 dB |
| 100% | -44 dB | 8.0:1 | 0.2 ms | 300 ms | 8 dB |
Attack clamped to Fairchild TC range (0.2–0.4 ms). Release clamped to mastering spec (300–5000 ms). Knee always wide (10–24 dB, tube-inherent). Tube warmth: even harmonics at 0.23 + tone × 0.32.
Preset-Specific Curves
When a factory preset is active, PRESSURE uses a signed-p² mapping centered at P=0.5 (the preset's home position). Each preset defines its own home parameters and scaling ranges, so the knob always feels musical relative to that preset's sweet spot.
centered = pressure - 0.5
t = sign(centered) × centered² × 4
P=0.0 → t=-1.0 (gentlest)
P=0.5 → t= 0.0 (home — the sweet spot)
P=1.0 → t=+1.0 (most aggressive)
param = home + t × range
See Presets for the full list of 34 factory presets with their home parameters.