Gong

Each strike starts as a shaped contact-force pulse, not a noise burst. Mallet hardness sets its nominal length, then the played pitch scales it within a 1.5 to 14 millisecond range: a higher note gets a shorter contact so the pulse cannot cancel its own modal excitation. A small filtered roughness residual can still ride on the pulse. The duration and pulse shape set the excitation bandwidth, so a compliant head reaches mostly low modes while a rigid head wakes the whole bank. That force drives an impulse response synthesised for the selected gong, pitch, position and velocity.

Bloom is baked into the IR as an amplitude split. Each mode gets a fraction of its energy marked as arriving late, rising toward zero to one over the bloom time while the mode's own exponential decay runs underneath; the product of a rising and a falling term peaks after the attack, and that peak is the swell. The fraction ramps with position in the mode bank, so the fundamental speaks immediately and the top of the bank arrives last. It is driven by bloom amount times the beater's coupling times velocity SQUARED, which is what makes it a nonlinearity rather than a knob: at a third of full velocity the drive is under a tenth.

Glide is a per-mode exponential detune with a one-over-one-plus-mode falloff, so the fundamental moves most and the body does not sound like a tape-speed bend. Motion scales the recipe behavior, Depth bounds the initial offset, and Settle controls its time course. The renderer integrates that contour to phase, so every affected mode starts sharp or flat and converges on its nominal frequency instead of jumping between pitches.

Because both effects depend on velocity, an IR is only reusable for strikes of similar force, so velocity is quantised into four buckets and the bucket is part of the cache key alongside note, gong, beater, position, size and every timbre parameter. Level still follows continuous velocity, so dynamics are smooth and only timbre steps. Each strike is a one-shot whose open duration grows from 2.5 to 8.5 seconds with velocity, followed by the Tail Fade; voices are capped at six with oldest-first stealing and a nine-second resource cap.