Dark2A

Dark2A

A faithful emulation of the LA-2A tube optical leveling amplifier — the legendary opto compressor with a real photocell gain element, prized for its slow, smooth, program-dependent leveling and warm tube/H2 character on vocals, bass, and bus. Dark2A reproduces the Vactrol-style photocell behavior and natural soft knee, keeping the authentic simplicity of just two controls, then adds modern extras (sidechain EQ, output EQ, parallel mix, transformer color) for flexibility.

Main panel — compression

PEAK REDUCTION (the main compression amount) — Like the LA-2A’s single compression control. Higher = more leveling/gain reduction.

GAIN — Makeup gain at the output.

COMP / LIMIT switch — COMP = gentle leveling-amp behavior; LIMIT = harder limiting (the LA-2A’s two-position mode switch).

FB / FF — Detector topology. FB (feedback) is default — authentic vintage LA-2A character, smooth and forgiving. FF (feedforward) is tighter, more transparent transient catch.

ON/OFF — Compression in/bypass.

There is intentionally no attack / release / ratio control — the LA-2A’s timing and ratio are inherent to the opto cell, just like the hardware.

Metering

VU — Gain reduction metering.

ADV panel

MIX (0…100%) — Parallel compression, blends dry with compressed.

INPUT (−18…+18 dB) — Pre-compressor input-gain trim (auto-compensated after, so level stays neutral).

KNEE (−10…+10):

• negative = harder knee — compression kicks in more abruptly at threshold, snappier/more aggressive.
• 0 = stock — the opto cell’s natural soft knee.
• positive = softer knee — compression eases in more gradually, smoother and more musical.

CHARACTER (0…100) — Drives the amount of photocell/tube harmonic coloration (H2-dominant warmth). 0 = cleanest; higher = more vintage harmonic character, which also grows naturally with gain reduction.

OUTPUT (−12…+12 dB) — Final post-everything output trim.

EQ display + EQ MODE (SC / OUT) — One 6-band parametric EQ display that toggles between two destinations:

• SC — Sidechain EQ: shapes what the detector hears, so the compressor reacts more or less to certain frequencies.
• OUT — Output EQ: post-compression tone shaping on the audio itself.

Drag bands on the display; per band On, Type (Bell/LShelf/HShelf/LCut/HCut), Freq/Gain/Q.

Transformer (combobox) — Output transformer emulation, 17 options (None, Carnhill, Sowter, Cinemag, Marinair, Haufe V72, Triad HS-30, Reichenbach, EA Edcor, Neve 1272, API 2520, UTC A-20, Peerless S-415, St Ives, Lundahl LL1538, Jensen JT-11, Tamura TKS-27). Default None keeps the transformerless sound.

Oversampling

x2 / x4 / x8 (combobox) — Anti-aliasing. Default x4.