Acme Audio Opticom XLA-3 MKII

Acme Audio Opticom XLA-3 MKII is a single-channel all-tube optical limiter built on the Teletronix LA-2A idea but with three compression curves instead of one. The circuit is point-to-point wired inside a 16-gauge solid steel chassis.

Three compression curves instead of one speed

The core limitation of a classic opto is its single fixed time constant: either it suits the material or it does not. The XLA-3 offers Normal, Fast and Slow modes driven by a triple optoelectronic circuit with CdSe photocells. In Slow mode transients pass through largely intact; in Fast the unit starts behaving closer to a FET design.

Tone set by how hard you drive the input

The Cinemag input transformer and the tube gain stage respond to level: run it politely and the path stays clean, push it and saturation and density arrive, pulling a vocal in front of the rest of the mix. A 15 dB pad lets you choose the operating point regardless of source level. Gain reduction reaches 29 dB and make-up gain 34 dB, so the unit covers both gentle levelling and aggressive drum bus compression. A stereo link connector pairs two units.

KEY FEATURES

• Single-channel optical limiter with an all-tube circuit
• Triple optoelectronic circuit using CdSe photocells
• Normal, Fast and Slow modes plus an Amp mode with no dynamics reduction
• Cinemag input transformer
• Switchable 15 dB input pad
• Hand-wired two-stage bypass and stereo link connector
• 16-gauge steel chassis, point-to-point wiring, Bakelite knobs

TECHNICAL SPECIFICATIONS

• Type: tube optical limiter, single channel
• Detection: triple optoelectronic circuit, CdSe photocells
• Modes: Normal, Fast, Slow
• Frequency response: 20 Hz - 20 kHz, +/- 1.4 dB
• Maximum gain reduction: 29 dB
• Make-up gain: 34 dB
• Input pad: 15 dB, switchable
• Input transformer: Cinemag
• Connectors: Neutrik XLR input and output, stereo link
• Metering: full-sized backlit panel meters
• Tube sockets: Micalex
• Power: 115/230 V AC via IEC inlet