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Niviem OPT4
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Niviem OPT4

Opto Leveling Amplifier

Inspired by the legendary Teletronix LA-2A Leveling Amplifier (1965). True feedback compression topology with T4 opto cell modeling, dual-mode opto response (Modern/Vintage), tube saturation, and UTC transformer coloration. Free plugin.

FREE
ManualQuick Start
Version
1.0.0
Released
February 2026
Formats
VST3, Audio Units
Platforms
macOS, Windows
Features

What Makes It Special

True Feedback Compression

Authentic feedback topology where the sidechain monitors the output signal. COMPRESS mode (~3:1) and LIMIT mode (~10:1+) emerge naturally from the circuit behavior.

T4 Opto Cell Emulation

Complete T4B electro-optical attenuator modeling with EL panel threshold, CdS photoresistor gamma curve, two-stage release, and program-dependent memory effect.

Modern / Vintage Opto Response

MODERN mode: clean, punchy compression with factory-fresh transformers. VINTAGE mode: warm, saturated compression with aged transformer coloration and deeper harmonic content.

Tube Saturation & Transformers

12AX7 input stage and 12BH7 output stage with Clean/Driven character switch. UTC input and output transformer modeling with B-H saturation curves and low-frequency iron core response.

Extended Sidechain Controls

Emphasis HPF (up to 1 kHz) and sidechain LPF for precise frequency-dependent compression. Attack and release character controls shape the compression envelope beyond the original hardware.

Dark / Bright Tone Modes

Dark mode emphasizes even-order warmth with lower tube coefficients. Bright mode brings out odd-order edge with higher drive. Parallel mix control for blend-to-taste compression.

Specifications

Inspired ByTeletronix LA-2A Leveling Amplifier (1965)
TopologyFeedback compression (opto-electronic)
Compress Ratio~3:1 (emergent from topology)
Limit Ratio~10:1+ (emergent from topology)
Attack~10ms (program dependent)
Release60ms to 50%, then 0.5-5s full recovery
EmphasisSidechain HPF, 0-1000 Hz
Sidechain LPFHigh-frequency sidechain rolloff
Gain Range-12 dB to +30 dB (default +10 dB)
Output Trim-100 dB to +12 dB
Oversampling4x fixed (internal)
Sample Rates44.1 kHz – 192 kHz
Processing64-bit internal, 32-bit float audio

Highlights

  • The most musical compressor ever made — LA-2A character
  • True feedback topology with program-dependent behavior
  • Two-stage release: 60ms fast + 0.5-5s slow recovery
  • Modern/Vintage opto response with distinct transformer character
  • Dark/Bright tone modes for tube saturation voicing
  • Attack and release character controls beyond original hardware
  • Emphasis HPF + sidechain LPF for frequency-dependent compression
  • Parallel compression mix, output trim, sidechain listen
  • 36 factory presets: vocals, bass, drums, mix bus, mastering
  • Tube saturation (12AX7/12BH7) and UTC transformer coloration

Under the Hood

T4B opto cell: EL panel + CdS photoresistor modeling
Memory effect: program-dependent release from CdS physics
Voltage divider gain reduction: R_photo / (R_photo + R_fixed)
12AX7/12BH7 tube harmonic generation (2nd, 3rd order)
UTC input/output transformer B-H saturation + LF iron core
4x oversampled tube saturation with ADAA
300ms VU meter ballistics (standard)

System Requirements

macOS

  • macOS 11.0 (Big Sur) or later
  • Intel or Apple Silicon (Universal Binary)
  • AU or VST3 compatible host

Windows

  • Windows 10 or later (64-bit)
  • VST3 compatible host