Utilities

Process

CV processor - sample-and-hold, track-and-hold, slew limiter, and portamento glide in one strip.

What is a Process?

A signal processor of this kind - sometimes called a CV processor or voltage processor - bundles four classic CV-shaping operations into one module: sample and hold (S&H), track and hold (T&H), slew limiter, and portamento glide. All four are variations on the same idea - controlling how a CV changes over time - but each takes a different approach.

A sample and hold watches the input continuously and freezes a snapshot whenever a gate rises. The output stays at that frozen value until the next trigger. It's the textbook way of converting noise or any continuous CV into stepped values for melodic or rhythmic use. A track and hold is the close cousin: instead of sampling on edges, it passes the input through unchanged while the gate is LOW and freezes the output while the gate is HIGH. Useful for capturing the precise value of an envelope at the moment a key is released, or for sampling a slow LFO at a specific moment.

A slew limiter is a different beast. It doesn't sample at all - it gradually follows its input, but at a maximum rate. If the input jumps from 0V to +5V instantaneously, the slew limiter takes a configurable amount of time to ramp from 0 to 5, smoothing the step into a slope. With a fast slew rate, transitions are nearly instant; with a slow slew rate, every change becomes a long curve. Slew is the basis of portamento (a synth keyboard's pitch glide between notes) and the basic mechanism of lag and glide modules in modular and analog synthesis.

Finally, portamento glide is slew with a twist: it only slews when a gate is held. Release the gate and the output snaps instantly to the new input value. This mimics the behavior of analog monosynths where pitch glides between notes that are played legato (overlapping) but jumps cleanly between notes played staccato. It's the difference between a flowing pitch line and a strict melodic phrase.

All of these are time-domain operations - they're about when voltages move, not where they go. They're how you give a discrete sequence of pitches the smooth contour of a sung melody, or how you turn a smooth modulation into a stepped one, or how you make sure a quickly-changing signal doesn't introduce clicks downstream.

Our Process

Our Process bundles six outputs into one panel: two-stage S&H (S&H 1 + S&H 2 shift register), T&H and H&T (a complementary track/hold pair), continuous SLEW, and gated GLIDE. Six time-domain operations on the same input signal, each available simultaneously - patch any of them, ignore the rest.

The slew rate parameter is shared between SLEW and GLIDE - when you set the slew time, both outputs respond at that rate. The unit is seconds-per-volt: a setting of 0.05 s/V means a 1V jump takes 50ms, a 5V jump takes 250ms. This is the most musical scaling we know - the larger the pitch interval, the longer the glide. A Slw CV input modulates the rate, so you can sweep it under control of an LFO for breathing portamento.

The two-stage S&H is the thing that makes this module more interesting than its peers. Patch one source into the input, one clock into the gate, and you get S&H 1 (current value) and S&H 2 (one trigger ago) simultaneously. Send them to two voices and you get a lagging canon for free, no S&H ASR panel required for the simple two-voice case.

In a patch

The standard generative patch: Noise into the input, a clock into the gate, take S&H 1 out into a Quantizer, then into a VCO V/Oct. Stepped random pitches snapped to a scale - the foundational sound of modular generative music.

For a melodic monosynth patch, take a step sequencer pitch CV into the input, the sequencer's gate into the GATE, and use the GLIDE output into the VCO. Notes played with overlapping gates glide; notes with separated gates jump cleanly. Adjust the slew time to taste - short for sharp playing, long for legato sweeps.

SLEW smooths anything. Patch a clicking square LFO through SLEW with a slow rate and the square becomes a smooth trapezoid - useful for filter modulation when the square's hard edges introduce audible clicks. Patch an envelope through SLEW to round off its corners for a softer attack.

Inputs

IN (cv) — CV signal input. This is the signal to be sampled, tracked, or slewed.
GATE (gate) — Gate input. Rising edges trigger S&H sampling. Gate state controls T&H and H&T behavior. Gate high enables Glide smoothing.
Slw (cv) — Slew rate CV modulation. Adds to the Slew knob for dynamic control of smoothing speed.

Outputs

S&H1 (cv) — Sample & Hold output 1. Captures the input voltage on each gate rising edge and holds it. Classic random voltage generator when fed noise.
S&H2 (cv) — Sample & Hold output 2. Holds the previous S&H 1 value, creating a one-step delay. Together with S&H 1, forms a two-stage shift register.
T&H (cv) — Track & Hold. Passes the input signal while gate is LOW, freezes the current value when gate goes HIGH.
H&T (cv) — Hold & Track. The opposite of T&H - holds the value while gate is LOW, tracks (passes through) while gate is HIGH.
SLEW (cv) — Continuously slew-limited version of the input. Smooths out jumps and sharp transitions at the rate set by the Slew knob.
GLDE (cv) — Portamento output. Applies slew smoothing only while the gate is HIGH. Perfect for legato note transitions in a melody.

Controls

Slew — Slew rate from 1ms/V (nearly instant) to 10s/V (very slow). Controls how quickly the Slew and Glide outputs track the input.

Inspired by

A small CV processing strip combining the four classic operations: sample on a gate edge (S&H), track until a gate freezes it (T&H/H&T), continuously slew-limit a signal (slew), and slew only while a gate is held (portamento glide).

Mutable Instruments Kinks
Make Noise Function S&H/T&H
classic sample/track-and-hold + slew utility

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