Air-G Pop!
User Manual
Version 1.0
Dynamics processor (compressor + gate) based on Pop3 by Airwindows.
Original source code published under open license by Chris Johnson.
User Manual
Version 1.0
Dynamics processor (compressor + gate) based on Pop3 by Airwindows.
Original source code published under open license by Chris Johnson.
Air-G Pop! is a dynamics processor with two independent sections — a compressor and a gate — based on the Pop3 algorithm by Airwindows. Unlike conventional compressors, Pop3 makes attack and release decisions per sample: each audio sample is either compressed or released in binary fashion, without the inertia of analog time-constant circuits. The result is an extremely fast response that captures transients with surgical precision.
Pop3 was designed by Chris Johnson as an evolution of his work on transient compression: a processor that gives pop — impact and presence — to drums, percussion, and any source where the articulation of the attack matters. The integrated gate lets you define the lower dynamic range boundary, from classic gating to simply cleaning up the background without abrupt cuts.
Air-G Pop! also features the AirW / AirG mode, which lets you choose between Chris’s original behavior (AirW — unguarded stereo coupling, vintage character) and an Air-G modern variant (AirG — guarded coupling, clean and predictable release). In AirG mode, the compressor knee is switchable between Hard and Soft.
“Pop3 brings punch and presence to transients. The attack and release happen on a per-sample binary basis — it either compresses or it doesn’t, each sample. This makes it very fast and very accurate in how it tracks dynamics.”
Air-G Pop! interface.
Sets the level above which the compressor starts acting. At its default value (0.0 dB, knob fully clockwise) the compressor barely acts, since few signals reach 0 dBFS. As you lower the threshold, more signal enters the compression zone and the effect becomes progressively more audible.
Defines how much the signal above the threshold is attenuated. At low values compression is gentle; at high values the behavior approaches a limiter. The range goes from 1:1 (no compression) to “Lim” (limiter). For transient compression with character, the 4:1 to 8:1 range is most commonly used.
Controls how quickly the compressor responds when it detects a signal above the threshold. Short attack times capture the transient front. Longer attack times let the initial impact pass before compressing, preserving the punch of the attack.
In Pop3, attack has unusual precision: by working per sample, the compressor can react before the next processing cycle ends. This makes it especially effective for drums and percussion where transient timing is critical.
Drums: 5–20 ms to let the initial hit through. Peak limiting: attack at minimum. Voice and guitar: start at 20–50 ms and adjust by ear.
Determines how quickly the compressor lets go of the signal once it drops below the threshold. A fast release returns the level quickly and can produce pumping if too short. A slow release is more musical but may compress more than necessary between transients. The range goes from tens of milliseconds to several seconds.
Defines how the compressor transitions between the uncompressed and compressed states around the threshold.
Hard: the compressor acts abruptly when crossing the threshold. More aggressive and defined; typical of fast compressors and limiters.
Soft: compression is applied gradually over a ±6 dB zone around the threshold. The transition is smoother and more musical; reduces the abrupt character at high RATIO values.
In AirW mode this control is hidden: the original Pop3 algorithm always uses a Hard knee.
The gate attenuates the signal when it falls below the threshold set by G THRESH. Unlike a classic binary-state gate (open/closed), Pop3’s gate uses a sine function that produces a smoother, more musical closure. The gate acts on both channels simultaneously using a mono average detector.
When G THRESH is set to “Off” (knob fully counter-clockwise) the gate is completely inactive and does not affect the signal.
Sets the level below which the gate starts acting. With G THRESH at “Off” the gate is disabled. As you raise G THRESH, the gate attenuates everything below that level.
Defines how much the signal is attenuated when it falls below the gate threshold. At low values attenuation is mild (soft gate, only reduces the background). At high values attenuation is nearly total: silence when the signal drops below the threshold.
Once the signal drops below the threshold, the gate waits this amount of time before starting to close. It works as a hold time: the gate stays fully open for G SUS milliseconds even though the signal is no longer above the threshold.
At 0 ms the gate starts closing immediately. At higher values (hundreds of milliseconds) the gate stays open longer, useful for sounds with long tails such as reverb, cymbals, or sustained guitar notes.
The displayed value (in ms) is an approximation calculated at the default G REL setting. When you change G REL, the actual hold time changes too. Use the value as an orientative reference and fine-tune by ear.
Controls how quickly the gate closes once the sustain period ends. A fast release produces an abrupt cut useful for drums to achieve maximum separation. A slow release produces a gentle fade out that sounds more natural on voices, guitars, and any source with organic decay.
Blends the compressed signal (wet) with the original unprocessed signal (dry). At 100% only the processed signal comes through. As you lower it, the original signal is progressively mixed in, implementing parallel compression directly in the plugin without needing to set up sends or aux buses in your DAW.
The typical result: the density and punch of the compressor, together with the transients and openness of the original signal. The gate always acts on the signal before the blend.
Dial in the compressor with MIX at 100%. Then lower MIX to between 40% and 70% to recover the body and dynamics of the original signal. Very effective on drums: heavy compression visible on the VU, but kick and snare sound punchier and more open than at full wet.
Controls the plugin’s output level. At 50% the output is at unity gain (0 dB). The range is −12 dB to +12 dB. Useful for recovering the level lost after compressing, or for attenuating if the plugin is saturating the signal chain.
Selects the stereo coupling algorithm for the compressor. This fundamentally changes the character of the plugin.
The stereo coupling acts on every sample unconditionally, even during release and silence. Airwindows’ anti-denormal dither keeps L and R perpetually slightly different, causing the coupling to keep “pushing” both compressors downward even without a real signal.
The result: compression never fully releases between transients. The VU stays elevated, the sound acquires continuous density, glue, and an unmistakable vintage character. The knee is locked to HARD, as in Chris’s original.
Ideal for: drums, 2-bus, any source where density, color, and glue matter.
The stereo coupling only acts when at least one channel is above the threshold. During release and silence, each channel releases independently at the rate set by the RELEASE knob. The result is a clean, predictable release without the “sticking” behavior of AirW.
In this mode the Knee button (Hard/Soft) is enabled: Hard for a more aggressive, defined compressor; Soft for a smoother, more musical transition around the threshold.
Ideal for: lead vocals, solo instruments, any situation where clarity and precise control matter more than character.
AirW: character, color, glue. Compression “sticks” to the sound and gives it continuous presence.
AirG: transparency, control, precision. Compression respects the release time you set and lets go cleanly.
The center meter shows the gain reduction (GR) the compressor is applying in real time. The needle at 0 means no compression; as the compressor acts, the needle moves to the left indicating how many dB of level are being reduced.
In AirW mode, the needle may stay elevated even during long pauses. This is a direct consequence of the algorithm’s “sticky” behavior, not a malfunction.
Indicates that the plugin is active and receiving audio. The LED turns off when the plugin is powered off or bypassed inside the DAW. It lights back up as soon as the plugin is active and receiving audio again.
Has two behaviors: when the output approaches the 0 dBFS limit (above −0.8 dB), the LED starts glowing gradually. This glow follows the signal in real time and is not persistent. If the output exceeds 0 dBFS, the LED latches at maximum and stays lit until the user clicks on it.
If the LED latches frequently during use, consider:
AirW mode. THRESH −12 to −18 dB, RATIO 4:1–8:1, ATTACK 10–20 ms, RELEASE 100–200 ms. G THRESH set to the room floor level. MIX 50–80% for parallel compression. Kick and snare gain presence; overhead compacts naturally.
AirG mode, Soft knee. THRESH −18 to −24 dB, RATIO 3:1–5:1, ATTACK 20–40 ms, RELEASE 150–300 ms. Gate with G THRESH at room floor level. MIX at 100%. AirG’s clean release lets the voice breathe between syllables without sticking.
AirW for glue, AirG for transparency. THRESH −6 to −12 dB, RATIO 2:1–4:1, moderate times. No gate. MIX 30–60% to preserve mix dynamics while gaining cohesion. OUTPUT adjusted to unity.
AirW or AirG depending on desired character. THRESH −20 to −30 dB, high RATIO (8:1 to Lim), ATTACK 1–5 ms. Aggressive gate: G THRESH at the level between hits, short G SUS, fast G REL. The VU will show pronounced GR peaks on each transient.
Air-G Pop! was developed by Air-G Audio as part of the plugin line based on Airwindows’ work.
The Pop3 algorithm is the work of Chris Johnson (Airwindows), whose original source code is published under an open license at github.com/airwindows. Air-G Pop! is a reimplementation of the original algorithm with original additions: Hard/Soft knee control, MIX knob for parallel compression, AirG mode with guarded coupling, gate with sustain control, and a gain reduction VU meter.
To Chris Johnson for his tireless work on Airwindows and for sharing decades of audio processing research completely openly.
Air-G Pop! v1.0 — Air-G Audio. The Pop3 algorithm is the work of Chris Johnson / Airwindows and is used under the terms of its open license.