OPT4

NIVIEM OPT4 is a free opto compressor plugin - a circuit-accurate emulation of the 1965 Teletronix LA-2A Leveling Amplifier, Jim Lawrence's design and the most-recorded compressor in history.

OPT4 is a true feedback compressor built around a modelled T4 electro-optical cell — an electroluminescent panel lighting a CdS photoresistor — the circuit that gives the LA-2A its smooth, program-dependent gain reduction. It keeps the authentic two-knob core (Peak Reduction + Gain — no threshold, no ratio) and adds musician-led controls: Attack and Release character, sidechain HF/Emphasis and low-pass, parallel Mix, Dark/Bright tube tone and a Modern/Vintage opto response.

INSIDE THE PLUGIN.

• True feedback compression with a modelled T4 opto cell (EL panel + CdS photoresistor).

• Two-stage, program-dependent release — the famous LA-2A "memory" behaviour.

• Compress (~3:1, soft) and Limit (~10:1+, firm) topologies.

• The authentic two-knob core — Peak Reduction + Output Gain, no threshold, no ratio.

• Attack & Release character · HF / R37 sidechain Emphasis · SC LPF · SC Listen.

• Parallel Mix · Output Trim · Dark/Bright tube tone · Modern/Vintage opto response.

• 12AX7 + 12BH7 tube saturation and UTC transformer modelling.

• Up to 32× oversampling · stereo-linked · 64-bit internal processing.

• 36 factory presets across 9 categories · user save / delete / rename.

• A/B Compare · hover tooltips with live values · double-click value entry.

• Nivipedia — an in-plugin encyclopedia, 52 articles; right-click any control for "What is this?"

• Cream-chassis interface styled after the vintage LA-2A.

NIVIEM AUDIO LTD — vintage hardware, built in code.

Youtube Demo: {See video at top of page}

OPT4 is developed by NIVIEM AUDIO LTD, an independent audio software company registered in England and Wales. Teletronix and LA-2A are trademarks of their respective owners; NIVIEM AUDIO LTD is not affiliated with or endorsed by them. OPT4 is an original emulation inspired by the classic hardware.