| Content | The Shelford Channel is built around Rupert Neve’s first new transformer-gain, class-A microphone preamplifier in over 40 years, a “best-of-the-classics” inductor EQ section, a tone-packed diode bridge compressor, the power of variable Silk saturation, a new dual-tap transformer output stage, and twice the operating voltage of vintage designs.
The Input Stage and Transformer Gain Mic Pre
Like Rupert’s designs from his time in Little Shelford , the Shelford Channel’s preamplifier uses a directly-coupled transformer input with gain provided by the custom transformer itself – a first in over 40 years for Rupert Neve. This new custom-designed input transformer, along with its careful integration with the surrounding class-A circuitry, is critical to the Channel’s bold and instantly recognizable character.
Conveniently, the Direct Input uses the same topology as the best-selling RNDI Active Transformer Direct Interface, providing astonishing clarity for high-Z instrument signals, with unparalleled low-frequency response and an incredibly smooth high end.
What is Silk?
The Silk & Texture circuit on the Shelford Channel allows you to fine-tune the amount (and type) of harmonic content in the output stage. This means your signal can be adjusted from quite transparent to settings that produce nearly 10x the amount of sonic color as Rupert’s vintage modules – and in two very unique modes. No matter what sound you’re looking for, Silk can help get you there.
The Dual Tap Transformer Output
Complementing the Silk circuit is the custom-designed output transformer, which uses Rupert Neve Designs’ unique dual-tap output topology. This offers both full-headroom (+26dBu) and -6dB outputs, allowing the engineer to drive the unit fully into classic transformer saturation without clipping converters and other devices later in the chain.
The “Best-Of” EQ
The Shelford Channel’s 3-band, custom-tapped inductor EQ was inspired by our favorite elements of Rupert’s vintage EQ designs. The low frequency band is designed to produce a creamy, resonant bass response similar to a vintage 1064 – but unlike the vintage modules, the LF band on the Shelford Channel can be used as either a shelf or a peak filter, adding punch, dimension, and control to your low end.
The midrange band is based on that of the 1073, ideal for sweetening vocals and instruments while bringing them forward in a mix, and its proportional “Q” response makes it well-suited for minimizing problematic frequencies. The high frequency band is a hybrid vintage / modern design, blending inductor circuitry with capacitor-based topologies to achieve vintage tones with enhanced control, with the shelf / peak corner switchable between 8K or 16K.
The Diode Bridge Compressor
Like the Inductor EQ and Transformer Gain microphone preamp, the Diode Bridge Compressor in the Shelford Channel is based on the same topologies found in Rupert’s vintage designs – but refined & adapted for the modern engineer.
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 Shelford’s diode bridge compressor is a dynamic tool equipped to make a statement on virtually any mix or track.
MIC PREAMP
INPUT IMPEDANCE
2200 Ohm
MAXIMUM INPUT
- +21.5 dBu from 150 Hz to 22 kHz
- +8 dBu 20 Hz to 22 kHz
NOISE
- Un-weighted, 22 Hz-22 kHz, source impedance 150 Ohm balanced.
- Main Out @ unity gain -100.9 dBu
- -6 dB Out @ unity gain -106.6 dBu
- +30 dB gain (Main Out) -91.37 dBu
- +66 dB Gain (Main Out) -64.1 dBu
- Equivalent Input Noise -121.37 dBu
FREQUENCY RESPONSE
+/-0.25 dB from 17 Hz to 45 kHz
DIRECT INPUT
MAXIMUM INPUT
8 dBu @ 20 Hz to 120 kHz
NOISE (MAIN OUTPUT)
-100 dBu (22 Hz to 22 kHz)
LINE INPUT
MAXIMUM INPUT LEVEL
+30.5 dBu 20 Hz to 30 kHz
TOTAL HARMONIC DISTORTION AND NOISE
- @ 1 kHz, +20 dBu output level, no load: Better than 0.002%
- @ 20 Hz, +20 dBu output level, no load: 0.05% Typical (2nd and 3rd harmonic)
NOISE (MAIN OUTPUT)
Un-weighted, 22 Hz - 22 kHz, source impedance 40 Ohm balanced, no load.
-101.1 dBu
FREQUENCY RESPONSE
+/- 0.25 dBu from less than 10 Hz to 110 kHz
-0.32 dB @ 120 kHz
MAXIMUM OUTPUT LEVEL
+26 dBu @ 16 Hz to 20 kHz
TOTAL HARMONIC DISTORTION AND NOISE WITH SILK ENGAGED
RED
- MIN TEXTURE @ 100 Hz, +20 dBu input level, no load: 0.0131%, mostly 3rd harmonic (typical)
- MAX TEXTURE @ 100 Hz, +20 dBu input level, no load: 1.66%, mostly 2rd harmonic (typical)
BLUE
- MIN TEXTURE @ 100Hz, +20 dBu input level, no load: 0.0079%, mostly 3rd harmonic (typical)
- MAX TEXTURE @ 100Hz, +20 dBu input level, no load: 0.941%, mostly 2rd harmonic (typical)
HIGH PASS FILTER
- Continuously variable swept frequency from 20 Hz to 250 Hz.
- Slope: 12 dB/Octave
EQ NOISE
Un-weighted, 22 Hz-22 kHz: -92 dBu
SIGNAL PRESENT
Illuminates GREEN when input stage signal level reaches -20 dBu
OVERLOAD INDICATOR
Illuminates RED when input stage signal level reaches -23 dBu
DIODE BRIDGE COMPRESSOR
- NOISE (BW 22 Hz – 22 kHz)
- 0 dB Makeup Gain: -84.5 dBu
- +20 dB Makeup Gain: -64.2 dBu
TIME CONSTANTS
- Measurements taken represent full range achievable between 1.5:1 Ratio and 8:1 Ratio setting.
- 0 dBu I/P 1kHz Burst Tone used for all recorded measurements.
- Fast (TC1): Attack 180µS — 1.8mS // Release 100mS – 150mS
- MedFast (TC2): Attack 750µS – 5.25mS // Release 160mS – 250mS
- Med (TC3): 2.7mS – 18mS // Release 350mS – 525mS
- MedSlow (TC4): 4.6mS – 38mS // Release 600mS – 1 S
- Slow (TC5): 11mS – 72.5mS // Release 800mS – 1.25 S
- Auto (TC6): 5.75mS – 35.5mS // Release T1 400mS – 850mS, T2 TBD
- “Fast” Mode Multiplier: Modifies aforementioned TC’s by 70% of original value
PRODUCT DIMENSIONS
19” (48.3 cm) x 10.5” (26.7 cm) x 1.75” (4.4 cm) | The vintage EQ tones you know & love.
The 551 is the only equalizer for the 500 Series actually designed by Rupert Neve. Featuring 3 bands of EQ inspired by Mr. Neve’s most prized vintage designs, along with custom-wound inductors, transformers and class-A gain blocks, the 551 brings the thick, powerful lows and sweet highs of Rupert’s classics to the 500-Series format.
The “Best-Of” EQ
The 551’s 3-band, custom-tapped inductor EQ was inspired by our favorite elements of Rupert’s vintage EQ designs. The low frequency band is designed to produce a creamy, resonant bass response similar to a vintage 1064 – but unlike the vintage modules, the LF band on the 551 can be used as either a shelf or a peak filter, adding punch, dimension, and control to your low end.
The midrange band is based on that of the 1073, ideal for sweetening vocals and instruments while bringing them forward in a mix, and its proportional “Q” response makes it well-suited for minimizing problematic frequencies. The high frequency band is a hybrid vintage / modern design, blending inductor circuitry with capacitor-based topologies to achieve vintage tones with enhanced control. The High Pass filter is a 12dB/octave design with a fixed 80Hz frequency, and can be used in tandem with the low frequency EQ to add low-end presence without clouding the source material.
As with Rupert’s most prized classic designs, each EQ section uses low-feedback, class-A discrete electronics to prevent low-level artifacts and harshness from detracting from the tonal shaping. However, this new circuit is a decidedly modern design with updated techniques and components that were simply not available 50 years ago, and is definitely not a “clone”.
What Are Inductors?
Inductors are wires wound around a coil that provide a form of frequency-dependant resistance. When they saturate, they bring out beautifully musical harmonics that give your tracks the smooth, polished sound that has made Rupert’s consoles and equipment so desirable for over fifty years. This is what makes them different from capacitor-based EQ designs, which do a great job at surgical equalization. But inductors provide the tone.
While it is certainly possible to create a functioning EQ using off-the-shelf inductors, we choose to use our own custom inductors for the 551. This attention to detail in controlling variables such as the winding and core materials in relation to the surrounding circuitry allows the 551 to capture the vitality and personality of Rupert’s classic designs.
NOISE
- Measured at Main Output, un-weighted, 22Hz-22kHz, source impedance 40 Ohm balanced.
- Better than -102 dBV
FREQUENCY RESPONSE
Main output, no load: +/- 0.1 dBu from 20 Hz to 31.5 kHz, -1 dB @ 120 kHz
MAXIMUM OUTPUT LEVEL
23.25 dBu
TOTAL HARMONIC DISTORTION AND NOISE
- @ 1 kHz, +20 dBu output level, no load: Better than 0.0025%
- @ 20 Hz, +20 dBu output level, no load: 0.13% Typical (2nd and 3rd harmonic)
HIGH PASS FILTER
- -2.7 dB @ 80 Hz
- Slope: 12 dB/Octave
NOISE
- Measured at Main Output, un-weighted, 22 Hz - 22 kHz, source impedance 40 Ohm balanced.
- Better than -94 dBV
FREQUENCY RESPONSE
Main output, no load: +/- 0.25 dBu from 20 Hz to 45 kHz, -2 dB @ 120 kHz
MAXIMUM OUTPUT LEVEL
23 dBu
TOTAL HARMONIC DISTORTION AND NOISE
- @ 1 kHz, +20 dBu output level, no load: Better than 0.009%
- @ 20 Hz, +20 dBu output level, no load: 0.13% Typical (2nd and 3rd harmonic)
POWER REQUIREMENTS
- 120mA on +16VDC
- 110ma on -16VD
| 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.
LINE INPUT TO LINE OUTPUT
- Compressor Bypassed.
- Z source = 40 Ohm Balanced
INPUT IMPEDANCE
10K Ohm
OUTPUT IMPEDANCE
40 Ohm
MAXIMUM INPUT LEVEL
+23.5 dBu
MAXIMUM OUTPUT LEVEL
+23.5 dBu
NOISE
- 22 Hz - 22 kHz BW.
- -101 dBu
FREQUENCY RESPONSE
- 10 Hz - 120 kHz, 30ft Output XLR Cable.
- +/- 0.25 dB
THD+N
- @ 1 kHz @ Maximum Output Level, 22 Hz - 22 kHz BW.
- 0.001%
| FEATURES
- 12-way precision rotary switch controls gain from 0 to 66 dB in 6 dB steps
- Continuously variable +/-6 dB level control
- Silk circuit, reduces negative feedback, adding harmonic content as needed
- Red Silk accentuates the saturation in the mid and high frequencies
- Same presence and sweetness found in standard Portico Series modules
|
Number of Channels |
Single |
|
Inputs |
1x XLR, balanced |
|
Output |
1x XLR, transformer-balanced |
|
Maximum Output Level |
+23dBu |
|
Meter |
8 segment LED meter |
|
Power Requirements |
Power Requirements @ +/-16VDC 100mA |
|
Dimensions |
Not specified by manufacturer |
|
Box Dimensions (LxWxH) |
10.2 x 7.8 x 2" |
|
- FAST – Fast Attack (750us), Fast Release (130ms)
- MF – Medium Attack (2.25ms), Fast Release (130ms)
- MED – Medium Attack (2.25ms), Medium Release (400ms)
- MS – Medium Attack (4ms), Slow Release (725ms)
- SLOW – Slow Attack (10ms), Slow Release (1S)
- AUTO – Medium Attack (5ms), Dual Decay Release (T1 500ms, T2 1s)The LINK switch allows the compressor to be linked to another 535 compressor module via a sidechain control voltage. In link mode, the compressor generating the greater sidechain voltage (resulting in higher amounts of compression) will control the compression of both audio signal paths to maintain proper stereo center image while compressing. Note: it is advisable to always audition the unlinked sound as well, to decide if the benefit of a constant stereo center image is worth the potential trade-off of reduced left / right independence in the stereo field.
-
SIDECHAIN HPF
- The S/C HPF switch allows the user to insert a 12dB/octave 150Hz high-pass filter in the compressor sidechain. 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 AND GAIN REDUCTION METERING
- These two LED meters provide accurate representations of both the output level of the compressor and the amount of gain reduction being applied to the input signal.
| This item is in excellent working condition and barely used.
The ZHA-4 splits a single stereo headphone output into four separate powered 1/8” headphone jacks, each with their own volume and mute control. Perfect for bands, podcasts, productions, and more.
Two AA batteries provide hours of portable power. For longer sessions, connect the USB-C port to a portable battery or plug directly into the wall.
What’s in the Box?
- ZHA-4 Handy Headphone Amplifier
- AA Batteries (x2)
- Stereo Mini Audio Cable (19” / 50cm)
- Quick Guide
Please Note: The item displayed in the images may not be the actual item you receive. |
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