F_STAMP

STAMP — Stereo VCA + ADSR (with ENV OUT)
STAMP is a compact stereo amplifier (VCA) with a built-in ADSR envelope. It can work as a normal stereo level/drive stage, or as a gated “amp envelope” for shaping audio. In addition, STAMP provides a dedicated envelope output so you can reuse the same envelope to modulate other modules.

Signal Flow Overview
Audio enters on L and R inputs, is scaled by the INPUT level control, then multiplied by an amplitude control signal. That control signal can be either the internal ADSR envelope (normal operation) or a constant value of 1.0 (NOENV mode). After the VCA stage, the signal passes through a tube-style overdrive stage and finally through an output level control before reaching the stereo outputs.

Jacks

• GATE IN (top area): Gate/trigger input for the ADSR. A gate above a small threshold starts (or holds) the envelope; when the gate goes low, the envelope enters its release phase.
• AM IN: Amplitude Modulation input. This is an external CV that can add (or subtract) gain modulation on top of the envelope-controlled level. Use it for tremolo, rhythmic pumping, sidechain-style shapes, or external dynamics control.
• L IN: Left audio input.
• R IN: Right audio input.
• L OUT: Left audio output.
• R OUT: Right audio output.
• ENV OUT: Envelope output (CV). This outputs the internal ADSR envelope as a control voltage, scaled to a typical modular range. This output is always the real envelope (even if NOENV is enabled for the VCA). If ENV LEN is negative, ENV OUT is inverted.

Envelope Controls (ADSR)
These controls define how the internal envelope evolves over time when a gate is received:

• ATTACK (ms): Time to rise from 0 to full level after the gate goes high.
• DECAY (ms): Time to fall from full level down to the sustain level while the gate remains high.
• SUSTAIN (V): The level held while the gate stays high. In STAMP this is shown in volts (0–5V) because the envelope is also available as a CV output.
• RELEASE (ms): Time to fall from the sustain level back to 0 after the gate goes low.

NOENV Switch
NOENV is designed for using STAMP as a straight stereo VCA/drive/output stage without envelope shaping. When NOENV is enabled, the VCA uses a constant value of 1.0 instead of the ADSR envelope, so the audio passes through at a steady level (still affected by INPUT, AM, DRIVE, and OUTPUT LEVEL). Important: ENV OUT still outputs the real ADSR envelope even when NOENV is enabled, so you can keep using the envelope elsewhere in your patch.

Level and Modulation Controls

• INPUT: Pre-VCA input trim for both L and R. Use this to set the incoming audio level before envelope/modulation and drive.
• AMPLITUDE MODULATION/ENV (AM amount): Bipolar depth control for the AM input. With AM amount at 0, the AM input does nothing. Positive values add modulation in the same polarity; negative values invert the modulation contribution.
• OUTPUT LEVEL: Final output gain after processing. Useful for matching levels into the next module or compensating for drive settings.

Drive

• OVERDRIVE: Tube-style saturation amount. Higher values add more harmonic distortion and density. Because drive can increase perceived loudness, use OUTPUT LEVEL to compensate and avoid clipping downstream.

ENV LEN (ENV OUT Length / Polarity)
ENV LEN affects only the ENV OUT envelope timing and polarity:

• Absolute value = time scale: 1.0 means the same timing as the main ADSR. Values below 1.0 make ENV OUT faster (shorter envelope). Values above 1.0 make ENV OUT slower (longer envelope).
• Negative values invert ENV OUT: If ENV LEN is negative, the ENV OUT voltage is inverted. This is useful when you want an opposite-direction modulation shape (for example, ducking a filter cutoff or inverting a VCA control elsewhere).
• Main audio envelope is unchanged: ENV LEN does not change how the VCA envelope behaves; it only changes the envelope copy sent to ENV OUT.

Typical Patch Examples

• Classic gated stereo amp: Patch a gate sequence into GATE IN, audio into L IN/R IN, and take L OUT/R OUT to your mixer. Adjust ADSR for plucks or pads, then add DRIVE if you want grit.
• Envelope as a general mod source: Patch ENV OUT to a filter cutoff, wavetable position, reverb mix, or anything that likes CV. NOENV can be enabled if you want the audio path steady while still using the envelope elsewhere.
• Sidechain-style movement: Feed a rhythmic CV into AM IN, set AM amount negative for “ducking” behavior, and use the ADSR to define the main shape while AM adds extra movement.
• Inverted envelope tricks: Set ENV LEN to a negative value and route ENV OUT to a parameter that you want to move opposite to the amplitude (e.g., brighten when the sound decays, or close a filter when the sound attacks).

Practical Notes

• Gate threshold: Very low gate levels may not trigger reliably. Use a proper gate/trigger source when possible.
• Hot signals and drive: If you drive the input hard and add overdrive, levels can rise quickly. Lower INPUT or OUTPUT LEVEL to keep things under control.
• AM is additive: AM is applied as an additional gain term. If you push AM amount too far, you can get extreme level swings; use moderate settings for musical results.

Controls Quick Reference

• ATTACK: Envelope attack time (ms).
• DECAY: Envelope decay time (ms).
• SUSTAIN: Sustain level (0–5V).
• RELEASE: Envelope release time (ms).
• NOENV: Bypass envelope for the VCA (audio uses constant 1.0); ENV OUT still outputs ADSR.
• INPUT: Input trim for stereo audio.
• AMOUNT (AM): Depth/polarity for AM IN.
• OVERDRIVE: Saturation amount.
• OUTPUT LEVEL: Final output gain.
• ENV LEN: ENV OUT time scaling (abs value) and inversion (negative values).