<h1>Rupert Neve Shelford 5051 Inductor EQ / Compressor</h1>
<span style="font-size:16px; font-style:italic;">Vintage-style three band EQ that captures the soul of Rupert Neve's classic designs, with modern capabilities</span><br/><br/>
The 5051 combines a classic three band EQ based on Rupert’s vintage designs with the power and flexibility of the Portico II compressor. Utilizing a fully-discrete, class-A signal path and high performance input and output transformers, the 5051 delivers the performance and musicality expected from a Rupert Neve Design.<br/><br/>
<h3>The Equalizer</h3>
The EQ design on the 5051 evokes sonic similarities with some of Rupert’s classic EQs. The 5051 uses a custom tapped inductor with selected capacitors to form the mid range equalizer band, and the shelf curves are based on Rupert’s vintage modules, including very similar frequency choices. Each EQ section also uses low feedback class-A discrete electronics to prevent low level artifacts and harshness from detracting from the tonal shaping. The EQ, however, is a modern design with advantages offered by techniques that were not possible 35 years ago along with improvements in electronic components currently available, and should not be considered a clone. Let’s just say it has heritage.
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Both the High and Low Band can be switched from Shelf to Peak curves and offer 15 dB of boost or cut. The High can be switched from 8 kHz to 16 kHz and the Low Band selected at 35 Hz, 60 Hz, 100 Hz or 220 Hz. The inductor based Mid Band offers 6 center frequencies; 200 Hz, 350 Hz, 700 Hz, 1.5 kHz, 3 kHz and 6 kHz. The Mid Band also has a High Peak switch to narrow the bandwidth or increase the Q of the filter. The 5051 includes an 18 dB/octave High Pass Filter with two corner frequencies on a lit button that toggles through “OFF, 60 Hz then 120 Hz indicated by a blue or red LED respectively.<br/><br/>
Additionally, the EQ can be switched Pre or Post the compressor. Normally the EQ precedes the compressor but the order can be selected so that the EQ follows after the Compressor. The 5051 also has two XLR balanced inputs that can be switched from the front panel. This allows the user, for example, to have a mic preamplifier and line input from a DAW to be pre-patched and easily selectable.<br/><br/>
<h3>The Compressor</h3>
The 5051 Compressor also features a discrete class A signal path proven used in the Portico Series, with individually controllable threshold, attack, release, makeup gain, ratio, side chain HPF, Feed-Forward / Feed-back selection and Peak/RMS detection modes. With the compressor inactive, the 5051 may be used as a transformer-coupled, high-performance line amplifier, and two 5051’s may be linked for stereo operation as well.
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<h3>How the Compressor Works</h3>
In order to control gain, a V.C.A. or Voltage Controlled Amplifier (or Attenuator) is used. There are many types of V.C. including the use of tubes, discrete and integrated solid state circuits and naturally non-linear devices, each one having its characteristic behavior that reflects sonically on the final performance, and gives it a character or signature that can be musically attractive or not! The Portico 5051 compressor makes use of a very accurate, low noise, low distortion V.C.A. having, essentially, no signature of its own.
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A part of the audio signal is rectified and smoothed to produce a suitable control voltage for the V.C.A. which has to respond very quickly and have low distortion. If the response is too fast, low frequency signals will themselves, be gain controlled! If the response is too slow, the signal will overshoot and the first few cycles will not get compressed. The speed and accuracy of the response, known as the “attack”, and the time frame that gain remains under the initial control, known as “release” or “recovery” and plays a large part in the way a compressor sounds.<br/><br/>
<h3>The Power Supply</h3>
The 5051 is intended for 5088 consoles or 5285 vertical frames. There are two +/- 24V power supply options; The 5-way supply is designed to sit in the bottom of a rack, and the 25-way supply is a 2U enclosure. The external +/- 24V supply provides exceptionally clean power, and reduces heat build-up within modules associated with DC-DC up-conversion.
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