RUPERT NEVE DESIGN 5254 Dual Diode Bridge Compressor

Dual Diode Bridge Compressor

The RUPERT NEVE DESIGN 5254 is a dual diode bridge compressor designed to evoke the spirit of early vintage Rupert Neve Designs diode bridge compressors while incorporating modern features such as advanced timing control, significantly lower noise floor, stepped controls, high voltage power supply, internal parallel processing, and more. Unlike VCA compressors, which are designed to achieve accurate sonic clarity, the rich harmonic content of the Dual Diode Bridge Compressor is designed to produce a wide range of sonic colorations. Based on the circuits of the famous Shelford Channel, the RUPERT NEVE DESIGN 5254 can operate in either dual mono or stereo mode, along with custom Rupert Neve Designs transformers and Class A electronics, all housed in a 1U 19” chassis.
Understanding the limitations of vintage unit topologies, RND's effort was to successfully reproduce the unique tone of these classic units while improving the noise floor, expanding the inflexible time constants, adding full-wave sidechain detection for improved dynamic response, and expanding the threshold and ratio controls. The Dual Diode Bridge Compressor, offering the powerful sound of these vintage units with controls tailored to modern needs, is a dynamic tool that can make its mark on any type of mix or track.
The unified TIMING controls consist of six selectable settings, carefully chosen for different applications, starting from the fixed, slow attack times of vintage units. The FAST and MF settings are designed to handle signals with many transients such as drums, plucked string instruments, and fast vocals. MED and MS have slightly slower attack and release times, allowing more transients to "pass through" with slightly longer recovery times. Finally, SLOW and AUTO are both very slow and have complex, non-linear release times, with softer and less audible level controls.
The FAST mode increases the speed of both attack and release times for each of the listed settings, effectively doubling the number of time constants from 6 to 12. FAST mode also allows for a significant increase in speed compared to vintage units, enabling greater versatility both sonically and operationally.
Faster TIMING settings will generally lead to greater peak-to-peak control voltage ripple, thereby introducing greater harmonic content, which translates into greater coloration in the signal path. Slower TIMING settings will significantly soften the voltage control, reducing the production of harmonic content and thus achieving more transparent compression. It is interesting to note that, due to the nature of the topology, these time constants adapt depending on various factors: ratio, threshold, and source material. These timing shifts and dynamically generated harmonic contents are precisely the factors that characterize the sonic personality of the Dual Diode Bridge Compressor.
Given the colorful sonic character of the RUPERT NEVE DESIGN 5254's diode bridge, this integrated parallel compression proves particularly useful. The BLEND control allows the user to introduce small amounts of extreme compression into another clean signal, creating an emphasized but natural sound that maintains dynamic range with adjustable color and "punch."
In addition to the TIMING control, the diode bridge compressor can be further manipulated with the RATIO, THRESHOLD, GAIN, S/C HPF, S/C INSERT, and LINK controls. The RATIO control has six selectable positions and allows the user to choose the slope of the compressor's curve with values ranging from 1.5:1 to 8:1. The THRESHOLD control allows the user to adjust the point at which compression begins, ranging from -25dBu to +20dBu. The GAIN control adds make-up gain ranging from -6dB to +20dB. The S/C HPF is 12dB per octave with a continuous frequency control from 20Hz to 250Hz. This feature can be immensely useful for making the compressor respond less to the powerful (and often sustained) low frequencies of a mix or instrument, which might otherwise cause the compressor to respond with a "muddy" sound. The SC INSERT has an always-active send/return for the compressor's sidechain, which can be used to insert a more adjustable EQ to further sculpt the compressor's response, or as a way to insert a key signal into the return, controlling compression via a separate source to act on the signal when the "key" signal goes above the threshold. LINK connects the control voltage of the two channels, so that when one channel is activated, the other will behave in the same way. This often helps maintain a solid central image in a stereo source.
NOTE: For stereo sources, it is always best to listen to the "unlinked" signal anyway, as linking can sometimes diminish the stereo width when the compressors are triggered only on one side.

Specifications

• XLR Line Input to XLR Line Output (Compressor Bypassed) ZSOURCE = 40 Ω Balanced
• Input Impedance: 10 kΩ
• Output Impedance: 40 Ω
• Maximum Input Level (+4dBu selected): +26.7 dBu typical
• Maximum Output Level: +26.7 dBu typical
• Noise (22 Hz - 22 kHz BW): -104 dBu typical
• Frequency Response (10 Hz to 120 kHz): +/- 0.25 dB typical
• THD + N @ 1 kHz @ Max Level (22 Hz - 22 kHz BW): 0.0008% typical
• Noise @ 0dB Make-Up Gain (22 Hz - 22 kHz BW): -84.5 dBu typical
• Noise @ +20dB Make-Up Gain (22 Hz - 22 kHz BW): -64.5 dBu typical
• FAST Attack 250μS - 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 5mS - 40mS // Release 600mS - 1S typical
• SLOW Attack 10mS - 80 mS // Release 800mS - 1.5S typical
• AUTO Attack 5mS - 40mS // Release T1 400-900mS, T2 1-2S typical