RUPERT NEVE DESIGNS 535 Diode Bridge Compressor

Diode Bridge Compressor

The RUPERT NEVE DESIGNS 535 is a diode bridge compressor originally developed for the acclaimed Shelford Channel’s dynamics circuit, which captures the soul of Rupert Neve’s original 2254 compressor while providing modern updates including advanced timing control, significantly lower noise, fully stepped controls and internal parallel processing capabilities.
Where the VCA compressor found in the Master Buss Processor provides unparalleled clarity, the thick, harmonically rich tonality of diode bridge compression can be essential to push key sources like vocals, electric guitars, bass, and drums to the forefront of a mix.
Understanding the limitations of vintage units such as the legendary 2254, a painstaking effort was made to reproduce the unique tone of these classics while improving noise floor and accuracy, expanding inflexible time constants, adding full-wave sidechain detection for improved dynamic response, and widening the threshold and ratio control ranges.
THRESHOLD: A 31-position potentiometer sets the level at which compression begins, from -25dB to +20dB. Turning this control counter-clockwise will increase the amount of compression, turning it clockwise will decrease the amount of compression.
RATIO: The RATIO control has six selectable positions on a rotary switch, allowing the user to set the slope of the compressor’s curve with pre-selected ratios from 1.5:1 to 8:1 for levels above the determined THRESHOLD. This range of compression ratios allows the user to compress moderately or heavily as desired.
TIMING: The unified TIMING control is a six-position rotary switch that sets the attack and release times of the compressor. The time can be further modified by the FAST button:

1. FAST – Fast Attack (750us), Fast Release (130ms)
2. MF – Medium Attack (2.25ms), Fast Release (130ms)
3. MED – Medium Attack (2.25ms), Medium Release (400ms)
4. MS: Medium Attack (4ms), Slow Release (725ms)
5. SLOW – Slow Attack (10ms), Slow Release (1S)
6. AUTO – Medium Attack (5ms), Dual-Decay Release (T1 500ms, T2 1S)

FAST: The FAST switch halves the attack and release times available on the TIMING control, effectively doubling the number of TIMING presets available to the user.
BLEND: The BLEND control has 31 steps and allows the user to blend the uncompressed (dry) signal with the compressed (wet) signal. Turning the control towards 0% will shift the mix to the fully uncompressed dry signal, while turning the control towards 100% will shift the mix to the fully compressed signal. This feature allows for parallel compression, enabling a wide range of compression subtleties.
GAIN: The GAIN control has 31 steps and allows the user to add make-up gain to the compressed signal to bring its level back to unity with the uncompressed input signal. It is much easier to evaluate the tonal effect of the compressor (via the COMP IN switch) when the compressed output level matches the uncompressed input level, thus eliminating potentially misleading level differences.
COMP IN: The COMP IN switch activates the compression circuit. By disengaging the COMP IN switch, the compressor is bypassed and the user can quickly compare the compressed sound to the dry input signal for an objective evaluation of the compressor’s sonic effect on the audio signal.
LINK: The LINK switch allows the compressor to be linked to another 535 compressor module via a side-chain control voltage. In link mode, the compressor generating the greater side chain voltage (resulting in the greater amount of compression) will control the compression of both audio signal paths to maintain a correct central stereo image during compression.
SIDE CHAIN HPF: The S/C HPF switch allows the user to insert a 12dB/octave 150Hz high-pass filter into the compressor’s side-chain. When this filter is engaged, the compressor will be significantly less sensitive to information below 150Hz. For example: when used on a drum kit, the low end of the kick drum would have a less proportional effect on the compression than a snare or cymbals, as a significant portion of the kick drum’s dynamic energy is focused below 150Hz.
LEVEL & GAIN REDUCTION METERING: These two LED meters provide highly accurate representations of both the compressor’s output level and the amount of gain reduction applied to the input signal.

Specifications

• Line input to line output (Compressor bypassed): Source z = 40 ohm balanced
• Input Impedance: 10k Ohms
• Output Impedance: 40 Ohms
• Maximum Input Level: +23.5 dBu
• Maximum Output Level: +23.5 dBu
• Noise: 22 hz - 22 kHz BW; -101 dbu
• Frequency Response: Output XLR Cable 10 hz - 120 kHz, 30 ft; +/- 0.25 db
• THD+N: @ 1 khz @ max output level, 22 hz - 22 kHz BW; 0.001%