Overview

Punchy, thick, and versatile.

Originally developed for the dynamics circuit of the acclaimed Shelford Channel, the 535 Diode Bridge Compressor captures the soul of Rupert Neve’s original 2254 compressor while providing modern updates including advanced timing control, significantly lower noise, fully stepped controls throughout, and internal parallel processing capabilities.

What is diode bridge compression?

Where the VCA compressor found in the Master Buss Processor provides unmatched clarity, the weighty, harmonically rich tonality of diode bridge compression can be essential in pushing key sources like vocals, electric guitars, bass and drums to the forefront of a mix.

By understanding the limitations of vintage units like the legendary 2254, painstaking effort was taken to reproduce the unique tone of these classics while improving the noise floor & accuracy, expanding inflexible time constants, adding full wave sidechain detection for improved dynamic response, and widening the range of threshold and ratio controls.

Delivering the powerful sound of these iconic designs with enhanced flexibility for the modern age, the 535 Diode Bridge Compressor is a dynamic tool equipped to make a bold statement on virtually any mix or track.

Features

THRESHOLD

A 31-position detented pot that 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 curve with pre-selected ratios of 1.5:1 through 8:1 for levels above the determined THRESHOLD. This range of compression ratios allows the user to compress as moderately or heavily as desired.

TIMING

The unified TIMING control is a six-position rotary switch that sets the compressor attack and release times. The timing can be further modified by the FAST button.

FAST (TC1) – Fast Attack (750 μs), Fast Release (130 ms)
MF (TC2) – Medium Attack (2.25 ms), Fast Release (130 ms)
MED (TC3) – Medium Attack (2.25 ms), Medium Release (400 ms)
MS (TC4) – Medium Attack (4 ms), Slow Release (725 ms)
SLOW (TC5) – Slow Attack (10 ms), Slow Release (800 mS - 1 S)
AUTO (TC6) – Medium Attack (5 ms), Dual Release (T1 500 ms, T2 1s)

FAST

The FAST switch speeds up all compressor time constants by 30%, effectively doubling the number of TIMING presets available to the user.

BLEND

The BLEND control has 31 detents and allows the user to mix the uncompressed (dry) signal with compressed (wet) signal. Turning the control towards 0% will shift the mix to fully uncompressed dry signal, whereas 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 subtlety.

GAIN

The GAIN control has 31 detents and allows the user to add make-up gain to the compressed signal in order to bring its level back up 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 is matched to the uncompressed input level, thereby eliminating potentially misleading level differences.

COMP IN

The COMP IN switch engages 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 higher amounts of compression) will control the compression of both audio signal paths to maintain proper stereo center image while compressing.

SIDE CHAIN HPF

The S/C HPF switch allows the user to insert a 12dB/octave 150Hz high-pass filter in the compressor side chain. When this filter is engaged, the compressor will be considerably less responsive to information below 150Hz. For example: if used on a drum kit, the low end of the kick drum would have less proportional effect on the compression than a snare drum or cymbals, since 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 output level of the compressor and the amount of gain reduction being applied to the input signal.

Specifications

MAXIMUM INPUT LEVEL

• +23.5 dBu

MAXIMUM OUTPUT LEVEL

• +23.5 dBu

INPUT IMPEDANCE

• 10K Ohm

OUTPUT IMPEDANCE

• 40 Ohm

THD+N

• @ 1 kHz @ Maximum Output Level, 22 Hz - 22 kHz BW.
• 0.001%

NOISE

• 22 Hz - 22 kHz BW, 40 Ohm balanced source. Noise specifications may vary depending on which 500 series chassis is being used, and / or interference from stray magnetic fields.
• -101 dBu

FREQUENCY RESPONSE

• 10 Hz - 120 kHz, 30ft output XLR Cable.
• +/- 0.1 dB

COMPRESSOR TIMING CONSTANT MEASUREMENTS

Note: TIMING measurements represent the full range between 1.5:1 and 8:1 ratio and FAST mode

• FAST – Attack 250 μS - 2 mS // Release 100 mS - 200 mS typical
• MF (MEDIUM FAST) – Attack 1 mS - 5 mS // Release 100 mS - 200 mS typical
• MED (MEDIUM) – Attack 3 mS - 18 mS // Release 350 mS - 700 mS typical
• MS (MEDIUM SLOW) – Attack 5 mS - 40 mS // Release 600 mS - 1 S typical
• SLOW – Attack 10 mS - 80 mS // Release 800 mS - 1.5 S typical
• AUTO – Attack 5m S - 40m S // Release T1 400-900 mS, T2 1-2 S typical

POWER CONSUMPTION (+/-16VDC): 100 mA

SHIPPING DIMENSIONS: 7.75“ (19.7 cm) x 10” (25.4 cm) x 3” (7.62 cm)

SHIPPING WEIGHT: 3 lbs (1.4 kg)