gain

Gain DEPENDS_ON signal: functional-operand necessity. The accepted gain definition is the ratio of an OUTPUT signal magnitude to its corresponding INPUT signal magnitude — both operands are signals. Remove the concept of signal (an engineered construct carrying information in measurable, transmissible form) and gain has no magnitudes to relate: the ratio is undefined. Present-tense removal test, not chronology; direction gain->signal is the dependent->operand.

Makeup gain is a gain stage: it applies amplification to restore signal level after compression. Its core operational mechanism is gain manipulation — the parameter it adjusts is the gain value in decibels. Remove gain and makeup gain has no mechanism to operate: it cannot amplify or restore level without the concept of amplification ratio. The removal test passes.

Distortion DEPENDS_ON gain as its operational mechanism: the accepted definition states 'driving an electronic signal beyond the linear operating range' which requires applying gain to push the signal past the linear threshold. Remove gain and distortion has no way to drive the signal into non-linear territory. Direction: distortion (dependent) → gain (operand), per Law 8b removal test.

Ducking operates by reducing the gain of one signal in response to another signal's presence. Remove gain — the measure of amplification factor that ducking manipulates — and ducking ceases to operate: its core mechanism is gain reduction triggered by external signal, not just gain reduction in general. Without gain as a parameter, ducking has no operational lever. Consistent with accepted precedent: compressor DEPENDS_ON gain, distortion DEPENDS_ON gain, upward-expansion DEPENDS_ON gain.

Pinned sense: the equalizer's core operation is per-band gain adjustment. Its accepted definition: it 'splits an audio signal into multiple frequency bands and independently adjusts the gain (amplification or attenuation) of each band', with 'gain amount (how much the band is boosted or cut)' as an explicit parameter. Removal test (Laws 2b/8b): remove gain — the measure of amplification factor, per its accepted definition — and the equalizer has no operational lever: boost and cut are gain adjustments, nothing else; without gain as a parameter it cannot shape tone. Coexists with the accepted equalizer DEPENDS_ON filter (the band-splitting mechanism) — different mechanism objects, both required, no conflict. Matches accepted precedent on the identical sense: compressor, upward-expansion, distortion, saturator, compression, DRC, makeup-gain, ducking, noise-gate, expander all DEPENDS_ON gain. Direction dependent->operand correct.

upward-expansion DEPENDS_ON gain: the accepted definition states it 'increases the gain of a signal when its level falls below a threshold.' The removal test passes — remove gain (the measure of amplification factor) and upward expansion ceases to operate: it has no mechanism to manipulate, no parameter to change. This is not a meta-level dependence; it's the core operational mechanism of the technique.

Compressor DEPENDS_ON gain as its core operational mechanism: it operates by reducing gain (gain reduction) when the signal exceeds a threshold. Remove gain — the measure of amplification factor that the compressor manipulates — and the compressor ceases to operate because gain reduction is its core mechanism; without gain there is no lever for the compressor to act on. Consistent with accepted precedent: upward-expansion DEPENDS_ON gain, saturator DEPENDS_ON gain, compression DEPENDS_ON gain.

Dynamic-range-processing (compression, expansion, limiting) operates by manipulating gain according to signal level: compressors reduce gain above threshold, expanders increase gain below threshold, limiters clamp peak gain. Remove gain and DRC has no mechanism — its entire function is gain manipulation. The removal test passes: without gain as an operational parameter, no dynamic range processor can function.

Noise-gate operates by attenuating (reducing) gain when signal level falls below threshold. Remove gain — the measure of amplification factor that the gate manipulates — and the gate ceases to operate: its core mechanism is gain reduction below threshold. Without gain as a parameter, the gate has no operational lever. Consistent with accepted precedent: compressor DEPENDS_ON gain, upward-expansion DEPENDS_ON gain, distortion DEPENDS_ON gain.

Removal test: remove gain (amplification of signal amplitude) and saturator — the device/algorithm that pushes gain into non-linear territory to produce warmth/grit — stops working. A saturator needs gain as its input mechanism: gain is cranked up until the circuit saturates. Without gain as a parameter, a saturator is just a passive component with nothing to do. The design purpose is to apply controlled gain beyond linear range.

Expander operates by attenuating gain for signals below threshold to increase dynamic range. Remove gain — the measure of amplification factor that the expander manipulates — and the expander ceases to operate: its core mechanism is gain reduction below threshold. Without gain as a parameter, the expander has no operational lever. Consistent with accepted precedent: compressor DEPENDS_ON gain, upward-expansion DEPENDS_ON gain, distortion DEPENDS_ON gain.

Compression (in audio, the process of reducing dynamic range) DEPENDS_ON gain: the removal test passes — compression operates by reducing gain (gain reduction) when the signal exceeds a threshold. Remove gain, and compression ceases to operate because gain reduction is the core mechanism; without gain there is no lever for compression to act on.