OCL-2 Electro-Optical Compressor/Limiter

Smooth Dynamics Processing Without Coloration

The OCL-2 is a two channel electro-optical compressor/limiter designed for the utmost in transparency, detail and versatility. Our short signal path design uses a custom optical input attenuation network in front of an all tube class A gain stage. Since the signal path is entirely transformerless, we've eliminated the coloration inherent in traditional transformer-coupled tube designs. The result is an open, detailed sound with an expanded sound stage and clarity that can only be achieved with modern tube circuitry.

The OCL-2's soft-knee design offers smooth, effortless dynamic control with the ratio adjustable from light compression to limiting. Our unique sidechain circuit linearizes the optical gain element to reduce distortion, and achieves much faster attack and release times than encountered with conventional optical compressors. And stereo linking is accomplished with the flip of a switch.

In the FAST mode, the optical cell operates with very fast attack and release times, which are peak-averaged by the rapid operation of the cell. This mode is remarkably free of pumping artifacts even at high compression levels. It's the ideal choice for 'invisible' dynamics processing, either for tracking or tight program compression. The PRESET mode consists of six classic attack/release time settings that are optimized for program compression, including two settings with program-dependent release times. The MANUAL mode offers total control over the attack and release times, which is particularly useful for creative compression effects or for processing bass guitar. Most important, the hard bypass switches on the front panel conveniently allow a quick determination of exactly what the OCL-2 is, or in most cases, isn't doing to your signal.

Specifications

Circuit Type: Class A vacuum tube signal path with transformerless output
Input Sensitivity: +4dBu
Input Impedance:  10Kohm
Frequency Response:  -1.0dB 8Hz and 145kHz with 10Kohm output load
Noise: less than -78dB below +4dBu output level with Output control at 0dB; less than -75dB below +4dBu output level with Output control at +20dB
Distortion: less than 0.05% THD+N, 20Hz to 10kHz, measured with +4 dBu input, +10dBu output, 600 ohm load
Output: +35dBu into 10Kohm load, +24dBu into 600 ohm load
Max. Gain Reduction: 27dB
Threshold: off to -20dB
Ratio: 1.5:1 to 15:1
Output: off to +20dB
Modes: fast (peak-averaged), preset or manual operation
Presets:  0.1s, 0.3s, 1s, 2s, 1 to 4s and 0.5 to 20s (program dependent)
Manual: attack time variable from 1.0ms to 40ms, release time variable from 0.1s to 2s
Meter: selection of input level, gain reduction, or output level, referenced to +4dBu = 0VU
In/Bypass: hard bypass of input signal to output connector
Link/Split: links channel 1 and channel 2 for stereo operation
Polarity: input and output XLR connectors are pin 2 hot
Vacuum Tubes: (2) 6072A, (2) 6922
Power: 120Vac, 30W (240Vac optional)
Power Supplies: +300Vdc, +12.6Vdc and ±15Vdc, fully regulated with soft-start warm-up and output muting

Dimensions

2U Enclosure: 19" x 3.5" x 12.5" (48.2 x 8.8 x 31.8 cm)
Weight: 14lbs (6.4kg)

Fast Features

Fast electro-optical input attenuator with an all tube signal path · Soft-knee design with fully adjustable compression ratio · Transformerless high voltage class A signal path · Low noise, wide bandwidth and superior transient response · Custom optical cells matched for precise stereo balance · Three sidechain operating modes: Fast, Presets and Manual · Two completely independent channels with stereo linking · Hard bypass switches for each channel · Sidechain inserts for frequency-dependent compression and de-essing · Transformerless output stage capable of delivering +35dBu · Soft-start warm-up with output muting · Gold-plated switch contacts, I/O connectors and tube sockets · Fully regulated high voltage (300V), filament and bipolar power supplies · Custom toroidal power transformer with shield for minimum hum · Polypropylene capacitors and metal film resistors · Single-sided audio pc boards to minimize capacitive interaction · Handcrafted in the USA

Notes:
0dBu = 0.775 Vrms
All noise measurements are unweighted, 20 - 20,000 Hz bandwidth
All Specifications are subject to change without notice