Rupert Neve Designs OptoFET® – Dual Stage Analog Compressor

OVERVIEW

The Rupert Neve Designs OptoFET is a highly versatile analog compressor and wave shaper, combining a newly-designed FET compression circuit with an optimised Optical compression circuit into a single rack space. There are two primary compression modes: in Dual Stage mode, the FET and OPTO compressors are used in series for complete dynamic control over critical sources, accomplishing a common recording & mixing technique with ease. In Dual Band mode, each compressor is assigned to either a low or high frequency band that can then be processed independently, which expands the tone-shaping and dynamic control of the OptoFET into uncharted territory.

From transparent vocal smoothing to extreme envelope shaping with massive harmonic texture, the OptoFET offers seemingly infinite creative control. Not only does each compressor have fully variable attack, release, threshold, make-up gain and parallel blend controls – plus side-chain high pass filters and special ‘GRIT’ and ‘BLOOM’ harmonic modes – the OptoFET also includes global controls to flip the order of the two compressors in Dual Stage mode, plus a unique variable crossover control to fine-tune the compression across upper and lower frequency bands in Dual Band mode. And though it is a single-channel unit, a pair of OptoFETs in dual mono – with 31-position fully detented controls – can add massive impact to stereo stems, groups, or even full mixes.

Intended for tracking, touring, mixing, mastering & sound design, the OptoFET provides immense control over the dynamics and tonal shape of your source. Compress creatively with the OptoFET.

KEY HIGHLIGHTS

All New FET Compressor Design:

For many years, the engineering team at RND has experimented with FET compressor designs – but it wasn’t until the OptoFET concept was solidified that releasing their first FET circuit felt ‘right’. While this FET compressor has some familiar characteristics, including ultra-fast attack times and common ratio settings, there are also several
features that make it instantly feel like a Rupert Neve Designs product and nothing else.

To start with, all variable controls for the OptoFET are via high-quality, 31-detent potentiometers, standard to most of our current products. The FET compressor includes variable Attack (with the fastest time being a blazing 100 microseconds), Release, Threshold, +20 dB of Make-up Gain and a parallel Blend control from 0% (dry) to 100%
(wet). Ratio can be set to either 4:1 or 8:1, and the 125Hz S/C high pass filter can be toggled on to leave the low end of a source untouched.

To further expand the OptoFET’s creative capabilities, a unique new ‘GRIT’ mode transforms the FET compressor into a powerful wave shaper, introducing ample harmonic distortion focused in the upper frequency range. GRIT can be used to either slightly accentuate sources so they ‘pop’ in just the right way or transform them into something entirely new. GRIT is also especially useful when combined with the blend control to achieve an exact amount of distortion character for a wide range of sources.

Optimised Optical Compressor Design:

RND has created several optical compression circuits over the years – including the Colour Comp in the wildly popular MBT (Master Bus Transformer) – but the circuit in the OptoFET was further developed to be the ideal complement to the faster, high-frequency focused FET compressor. In contrast, the OPTO compressor generates low-order harmonics while also having much slower attack and release settings.

For controls, the OPTO compressor includes variable Attack (starting at 5 milliseconds), Release, Threshold, +20 dB of Make-up Gain and parallel Blend controls, arranged in the same way on the front panel as the FET section. Ratio can be set to either 2:1 or 5:1, and it also includes a 125Hz S/C high-pass filter.

Where the FET section has its new ‘GRIT’ mode, the OPTO section contains another unique new mode called ‘BLOOM’. With BLOOM engaged, the low-order harmonics increase significantly, instantly making sources warmer, rounder and more pronounced in the low end. BLOOM can help make final adjustments without the use of a traditional EQ, especially when used with the Blend control.

Dual Stage or Dual Band? You Decide.

Some of the OptoFET’s most unique & powerful features lie in the global control section. In this section, the serial order of the 2 compressors can be ‘flipped’ while in Dual Stage mode. However, the OptoFET can also become a Dual Band compressor by simply pressing the ‘X-OVER IN’ button, which engages the Crossover filters and the
corresponding ‘CROSSOVER’ variable frequency control. With this mode engaged, each compressor is assigned to either the low or high frequency band, allowing for independent processing of both bands simultaneously. The variable frequency selection control dials in exactly where the crossover is applied, from 50Hz to 500Hz.

The ‘FLIP’ button also works while in Dual Band mode, assigning the FET or OPTO to process either frequency band as desired. This can be especially helpful for bass sources, providing complete control over the low-end while boosting the mids and highs to dial in the perfect amount of string noise and texture.

Multiple Gain Stages:

The OptoFET contains several gain staging options, starting with +/- 12dB input & output trim controls, ensuring the compression stays smooth & transparent. Alternatively, they can be used to drive the compressors, bringing out novel & interesting harmonic tones without clipping the custom transformer-balanced output stage. In addition, each compressor has its own make-up gain, with one driving into the next in Dual Stage mode. In Dual Band mode, the make-up gains can be used for tonal balance adjustments ranging from subtle to dramatic. As with most exceptional compressors, many of the controls and settings are gain-dependent, which is why the OptoFET begs for experimentation at every turn.

FEATURES

• All new FET compressor design and optimised OPTO compressor design in a single 1U unit
• Flexible Dual Stage or Dual Band compression modes
• Independent, comprehensive control sets for each compressor
• Unprecedented levels of dynamic and harmonic control
• Independent Blend controls for each compressor, making parallel processing a breeze
• Dual Stage mode: Easily flip the order of each compressor with the touch of a button
• Dual Band mode with Crossover control allows each compressor to process 2 frequency bands (lows and highs) independently
• All-new GRIT and BLOOM modes greatly enhance harmonic content and allow for source wave shaping
• Combine 2 units for extremely versatile dual mono processing on stereo sources
• Global Input & Output Trim for total control over gain staging and harmonics

OptoFET FRONT PANEL CONTROLS

FET Compressor:

ATTACK — 31-detent potentiometer that controls the FET compressor attack time within a range of 100uS to 50mS.

FET IN — Illuminated push-button switch that engages the FET compressor, making it possible to make quick A/B comparisons.

THRESHOLD — 31-detent potentiometer that controls the FET compressor threshold range from +20dBu to -15dBu.

GR METER — 8-segment LED meter that indicates FET compressor gain reduction in dB.

SC HPF —  Illuminated push-button switch that engages the side-chain high-pass filter. The HPF has a 12dB/octave slope that helps control the amount of low-frequency energy hitting the compressor side-chain when engaged. The corner frequency of the HPF is fixed at 125Hz.

GAIN — The GAIN control is a 31-detent potentiometer designed to add make-up gain to the compressed signal.

RELEASE — 31-detent potentiometer that controls the FET compressor release time within a range of 50mS to 3S.

RATIO — Push-button switch that selects between a 4:1 or 8:1 ratio.

GRIT — Illuminated push-button switch that adjusts the S/C detection circuit to generate more harmonic content.

BLEND — The BLEND control is a 31-detent potentiometer that allows the user to adjust the ratio of the compressed (wet) signal with the uncompressed (dry) signal to achieve parallel compression. Turning the BLEND control fully counterclockwise adjusts the mix toward the fully dry, uncompressed signal. Turning the BLEND control fully clockwise adjusts the mix toward the fully wet, compressed signal.

OPTO Compressor:

ATTACK — 31-detent potentiometer that controls the OPTO compressor attack time within a range of 5mS to 50mS.

OPTO IN — Illuminated push-button switch that engages the OPTO compressor, making it possible to make quick A/B comparisons.

THRESHOLD — 31-detent potentiometer that controls the OPTO compressor threshold range from +20dBu to -10dBu.

GR METER — 8-segment LED meter that indicates OPTO compressor gain reduction in dB.

SC HPF — Illuminated push-button switch that engages the side-chain high-pass filter. The HPF has a 12dB/octave slope that helps control the amount of low-frequency energy hitting the compressor side-chain when engaged. The corner frequency of the HPF is fixed at 125Hz.

GAIN — The GAIN control is a 31-detent potentiometer designed to add make-up gain to the compressed signal.

RELEASE — 31-detent potentiometer that controls the OPTO compressor release time within a range of 50mS to 3S.

RATIO — Push-button switch that selects between a 2:1 or 5:1 ratio.

BLOOM — Illuminated push-button switch that adjusts the S/C detection circuit to generate more harmonic content.

BLEND — The BLEND control is a 31-detent potentiometer that allows the user to adjust the ratio of the compressed (wet) signal with the uncompressed (dry) signal to achieve parallel compression. Turning the BLEND control fully counterclockwise adjusts the mix toward the fully dry, uncompressed signal. Turning the BLEND control fully clockwise adjusts the mix toward the fully wet, compressed signal.

Global Controls:

SIGNAL — LED that illuminates GREEN when the input signal is present and RED when near the clip point.

INPUT — 31-detent potentiometer that controls the input level within a range of +/-12 dB.

BYPASS ALL — Illuminated push-button switch that engages a hard-wire bypass for both the FET and OPTO compressor sections.

X-OVER IN — Illuminated push-button switch that engages cross-over filters and the corresponding CROSSOVER frequency control.

FLIP — Illuminated push-button switch that places the OPTO compressor before the FET compressor in the signal path.

FET STATUS — LEDs that indicate where the FET compressor is located in the signal path (A=1st, B=2nd) and whether it is compressing the LF (low frequency) or HF (high frequency) band when X-OVER is engaged.

CROSSOVER — 31-detent potentiometer that selects the corner frequency point of the crossover filters.

OPTO STATUS — LEDs that indicate where the OPTO compressor is located in the signal path (A=1st, B=2nd) and whether it is compressing the LF or HF band when X-OVER is engaged.

OUTPUT METER — 8-segment LED meter that indicates final output level in dBu.

OUTPUT — 31-detent potentiometer that controls the output level within a range of +/-12 dB.

POWER — LED that illuminates GREEN when the power is ON.

TECHNICAL SPECS

Note: All specifications are TYPICAL.
XLR Line IN to XLR Line OUT (Compressor Bypassed)

Input Impedance: 10 kΩ

Output Impedance: 40 Ω

Maximum Input Level @ 1 kHz: +24 dBu

Maximum Output Level @ 1 kHz: +24 dBu

Noise (22 Hz – 22 kHz BW): -96 dBu

Frequency Response:

• 6 Hz to 70 kHz: +/- 0.1 dB
• <5 Hz to 183 kHz: -3 dB

THD+N @ 1 kHz:

• 0 dBu: 0.002%
• +20 dBu: 0.0006%

FET COMPRESSOR SPECS

Noise (22 Hz – 22 kHz BW): -82 dBu

Attack Time: 100μS – 50mS

Release Time: 50mS – 1.5S

OPTO COMPRESSOR SPECS

Noise (22 Hz – 22 kHz BW): -93 dBu

Attack Time: 5mS – 50mS

Release Time: 50mS – 1.5S

Note: Compressor time constant ranges represent the full range achievable within all front panel settings.

Unit Dimensions: 1RU

• Width — 48.3 cm (19”)
• Depth — 21 cm (8.25”)
• Height — 4.5 cm (1.75”)

Unit Weight: 3.6 kg (8 lbs.)

Shipping Dimensions:

• Width — 61 cm (24”)
• Depth — 33 cm (13”)
• Height — 10.2 cm (4”)

Shipping Weight: 4.1 kg (9 lbs.)

DOWNLOADS

User Manual