Level
Makeup volume after compression.
- Turn up Louder compressed signal.
- Turn down Quieter; less boost after the squeeze.
Pedals / Compressor
Blue Comp
Compressor · play-tested
seth — fish
seth@ninevolt:~$
Knobs
In the TUI each knob runs from low (left / 0%) to high (right / 100%). Start near noon, then nudge while you play.
Sustain
How hard the compressor squashes your dynamics.
- Turn up More even volume — quiet notes rise, peaks get controlled; feels “sticky.”
- Turn down More natural dynamics — closer to uncompressed playing.
Inspired by
Boss CS-1 Compression Sustainer (1978) — Roland optical compressor using HTV-class optocouplers (LED + LDR). Sustain sets compression depth and release time; Level is output volume. Kurt used CS-style sustain on Nevermind (e.g. “Something in the Way” intro per profile notes); Metallica Master of Puppets profiles use it for studio glue.
Signal path
| Step | What it does |
|---|---|
| Input HPF ~90 Hz | Input/output coupling class — rolls sub-bass before detection (Eichas §4). |
| Sidechain peak detector | Rectified peak with ~3 ms attack — Ge diode detector equivalent. |
| Optical cell LED/LDR | Brightness tracks peaks; ~85 ms circuit attack (C3), ~420 ms LDR release. |
| Gain from LDR curve | Log-like LDR mapping; Sustain sets compression ratio (Rsustain pot, up to ~10:1). |
| Input × gain | Wet multiply — optical gain reduction on conditioned input. |
| Level + clamp | Level output trim (0.22 + level × 1.15). |
How we modeled it
CS-1-style input HPF → sidechain → optical cell → gain. Sustain maps to the Rsustain feedback divider (ratio/threshold), not LDR release time — sustain character comes from holding compression longer via ratio. Factory MoP Studio preset targets moderate squash with high sustain.
Simplifications
- Single generic optocoupler curve (not measured P873 vs VTL5C2) - No input/output buffering or CS-1 factory output-resistor variants - Sidechain taken from input, not post-amp tap as on some CS-1 revisions - Not CS-2 / CS-3 (VCA topology)