Rupert Neve Designs Shelford 5051 User manual

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Operations Manual
Shelford 5051
Inductor EQ / Compressor

Shelford 5051 Inductor EQ / Compressor
Thank you for your purchase of the 5051 Inductor EQ / Compressor. Everyone at
Rupert Neve Designs hopes you enjoy using this tool as much as we have enjoyed
designing and building it. Please take note of the following list of safety concerns
and power requirements before the use of this product.
Safety
It’s usual to provide a list of “do’s and don’ts” under this heading but mostly these
amount to common sense issues. However here are some reminders:
Don’t operate your 5051 module in or around water! Electronic equipment and
liquids are not good friends. If any liquid is spilled such as soda, coffee, alcoholic
or other drink, the sugars and acids will have a very detrimental effect. Sugar
crystals act like little rectiers and can produce noise (crackles, etc.). SWITCH OFF
IMMEDIATELY because once current starts to ow, the mixture hardens, can get
very hot (burnt toffee!) and cause permanent and costly damage. Please contact
support as soon as possible at [email protected] for resolution.
Safety Instructions: 1) Read these instructions.
2) Keep these instructions.
3) Heed all warnings.
4) Follow all instructions.
5) Do not use this apparatus near water.
6) Clean only with dry cloth.
7) Do not block any ventilation openings. Install in accordance with the
manufacturer’s instructions.
8) Do not install near any heat source such as radiators, heat registers, stoves, or
other apparatus (including ampliers) that produce heat.
9) Do not defeat the safety purpose of the polarized or grounding-type plug. A
polarized plug has two blades with one wider than the other. A grounding type plug
has two blades and a third grounding prong. The wide blade or the third prong are
provided for your safety. If the provided plug does not t into your outlet, consult
an electrician for replacement of the obsolete outlet.
10) Protect the power cord from being walked on or pinched, particularly at plugs
convenience receptacles and the point where they exit from the apparatus.
11) Only use attachments/accessories specied by the manufacturer.
12) Unplug this apparatus during lightning storms or when unused for long periods
of time.
13) Refer all servicing to qualied service personnel. Servicing is required when the
apparatus has been damaged in any way, such as when power-supply cord or plug
is damaged, liquid has been spilled or objects have fallen into the apparatus, the
apparatus has been exposed to rain or moisture, does not operate normally, or has
been dropped.
14) Do not expose this apparatus to rain or moisture.
15) The apparatus shall be connected to a mains socket outlet with a protective
earthing connection.

5051: Front Panel
-15 +15
0
-15 +15
0
-15 +15
0
-6dB +20
100mS 2.5 S
250 1 S
-30dB +20dB
-10 +10
GAIN
1.1:1 40:1
RATIO
1.5:1 3:1
FF
FB
LO PEAK
8K
16K
THRESH
S/C HPF
RELEASE
LINK
5mS 75mS
AT TAC K
25 50
COMP IN
EQ IN
EQ PRE
POST
220
100
60
35
MID FREQ
MID HI Q
LOW FREQ
0
22
20
18
14
10
4
-2
-10
1
2
4
6
10
14
18
22
LevelGR
3K
1.5K
700
350
200
6K
HF
MID
LF
HI PEAK
HPF
Red 120Hz
Blue 60Hz
INDUCTOR EQ
5051 EQ/ Com p r essor
COMPRESSOR
LINE 1
LINE 2
Threshold
Sets the level at which
compression begins
Ratio
Changes the amount of
gain reduction above the set
threshold level
Attack Time
Changes the time delay
before compression begins
Release Time
Changes the time taken for
the gain return to 0 after the
compressor disengages
SC HPF
Applies a HPF at 250 Hz to the
VCA side chain signal
FF/FB
When engaged, changes the VCA
detection from feed-forward to
feed-back
Level & Gain Reduction Meters
8 segment LED Meter for
monitoring gain reduction
and output level
Comp IN
Engages the Compressor
Make-Up Gain
Applies post-compressor
make-up gain
Link
Links the 5051 VCA to the 5051
module to which it is connected
HPF
Line Select
Mid Parametric
Low Frequency EQ
High Frequency Shelf / Peak
Cycles between bypassed, HPF at
60 HZ, and HPF at 120Hz
Selects between line 1 and
line 2
Selectable at 35, 60, 100, and
220 Hz. Continuous gain from -15 to
+15dB Selectable peak or shelf curves.
Selectable at 200, 350, 700,
1.5 K, 3 K, and 6 KHz. With
continuous gain from -15 to
+15dB. Selectable Hi Q.
Selectable at 8 and 16 Khz. With
continuous gain from -15 to +15dB.
Selectable peak or shelf curves
EQ Pre / Post
When engaged, moves the
EQ after the compressor

LineInputs
Twotransformer-balancedXLR
linelevelinputsselectableon
thefrontpanel
LineOutput
Transformer-balancedline
level,XLRoutput
S/CInsert
Sendsandreturnsasidechain
signaltothecompressorVCA.
Thereturninputcanbeusedas
a“key”inputforthecompressor.
Note:TheS/Cinsertisahalf-normal
connection,soifthereisnosignalon
theS/Cinsertreturnwhenitis
pluggedin,therewillnotbeany
compression.
PowerIn
4pinpowerconnectionwith
+/-24VDCfromspecialized
5051rackmountpowersupply
Link
Linkstwoormore5051
module’scompressorstogether
byconnectingthe“linkin”jack
tothe“linkout”jackonanother
compressor
POWER
LINE
1
LINE
2
OUTPUT
RUPERT NEVE DESIGNS, LLC
MODEL 5051
MADE IN USA
S/C INSERT
LINK
OUT IN
SND RET
5051:
Back Panel

Power Requirements
Each Shelford 5051 is tted for use with a specialized stand alone, multi-unit power
supply modules. The power supplies feature a proprietary 4 pin polarized input for
+24 and -24V DC power input, and come in 5-way and 25-way options. The 5-way
is a brick & 25-way.
The Need for Dynamic Control
The dynamic range of sounds we hear around us in normal life greatly exceeds the
capability of our best recording and processing equipment - but even if this were
not so, the scale of dynamic range must be accommodated to the venue in which
it is to be reproduced. For example, actual volume levels of the dance hall would
be deafening in a students bedroom. In the same way, late night listening in a
quiet living room demands careful adjustment of dynamic range. In the constantly
changing background noise of a car, drama dialog does not work without constant
attention to the level control. In the eld of communications, it is often necessary
to ensure that the best possible signal-to-noise ratio is obtained, in the interest of
intelligibility, within the limited performance of, say, a reporter’s recording device.
Digital recorders are unforgiving when overloaded. Overload can be avoided with
careful use of high ratio compression - on the verge of limiting - with careful choice
of time constants. A recording that still sounds “loud” can be produced without
non-musical harmonic distortion. A compressor-limiter is one of the most powerful,
yet subjective items in the sound engineer’s armory. Compression should never be
obvious to the listener and this needs intuitive and effective controls on the part of
the designer together with considerable skill on the part of the sound engineer.
A NOTE ON DISTORTION
The human hearing system is a remarkably complex mechanism and we seem to
be learning more details about its workings all the time. For example, Oohashi
demonstrated that arbitrarily ltering out ultrasonic information that is generally
5051:
Back Panel
5051: Block Diagram
Compressor S/C
Thresh Attack
ReleaseRatio
VCA
HPF
S/C Send/Return
In pu t
Tran sformerOu tpu t
Tran sformer
Meter
Ou tpu t
Reduction
Meter
EQ In
HPF In
G ain
Compressor In
EQ Pre/Post
FF/FB
Mid BandShelves
HPF
IP 1
IP 2
Input Select
Link

considered above our hearing range had a measurable effect on listener’s
electroencephalo-grams. Kunchur describes several demonstrations that have shown
that our hearing is capable of approximately twice the timing resolution than a limit
of 20 kHz might imply
(F=1/T or T=1/F). His peer reviewed papers demonstrated that we can hear timing
resolution at approximately with 5 microsecond resolution (20 kHz implies a 9
microsecond temporal resolution, while a CD at 44.1k sample rate has a best-case
temporal resolution of 23 microseconds).
It is also well understood that we can perceive steady tones even when buried under
20 to 30 dB of noise. And we know that most gain stages exhibit rising distortion at
higher frequencies, including more IM distortion. One common IM test is to mix 19
kHz and 20 kHz sine waves, send them through a device and then measure how
much 1 kHz is generated (20-19=1). All this hints at the importance of maintaining
a sufcient bandwidth with minimal phase shift, while at the same time minimizing
high frequency artifacts and distortions. All of the above and our experience listening
and designing suggest that there are many subtle aspects to hearing that are beyond
the realm of simple traditional measurement characterizations.
The way in which an analog amplier handles very small signals is as important
as the way it behaves at high levels. For low distortion, an analog amplier must
have a linear transfer characteristic, in other words, the output signal must be an
exact replica of the input signal, differing only in magnitude. The magnitude can be
controlled by a gain control or fader (consisting of a high quality variable resistor
that, by denition, has a linear transfer characteristic.) A dynamics controller - i.e.
a compressor, limiter or expander - is a gain control that can adjust gain of the
amplier very rapidly in response to the uctuating audio signal, ideally without
introducing signicant distortion, i.e. it must have a linear transfer characteristic. But,
by denition, rapidly changing gain means that a signal “starting out” to be linear
and, therefore without distortion, gets changed on the way to produce a different
amplitude.
Inevitably our data bank of “natural” sound is built up on the basis of our personal
experience and this must surely emphasize the importance of listening to “natural”
sound, and high quality musical instruments within acoustic environments that
is subjectively pleasing so as to develop keen awareness that will contribute to a
reliable data bank. Humans who have not experienced enough “natural” sound
may well have a awed data bank! Quality recording equipment should be capable
of retaining “natural” sound and this is indeed the traditional measuring stick. And
“creative” musical equipment should provide the tools to manipulate the sound
to enhance the emotional appeal of the music without destroying it. Memory
and knowledge of real acoustic and musical events may be the biggest tool and
advantage any recording engineer may possess.
One needs to be very careful when one hears traces of distortion prior to recording
because some avors of distortion that might seem acceptable (or even stylish)
initially, may later prove to cause irreparable damage to parts of the sound (for
example, “warm lows” but “harsh sibilance”) or in louder or quieter sections of
the recording. Experience shows that mic preamps and basic console routing paths

should offer supreme delity otherwise the engineer has little control or choice of
recorded “color” and little recourse to undo after the fact. Devices or circuits that
can easily be bypassed are usually better choices when “color” is a consideration
and this particularly is an area where one might consider comparing several such
devices. Beware that usually deviations from linearity carry at least as much long-
term penalty as initial appeal, and that one should always be listening critically
when recording and generally “playing it safe” when introducing effects that cannot
be removed.
1. Tsutomu Oohashi, Emi Nishina, Norie Kawai, Yoshitaka Fuwamoto, and Hishi
Imai. National
Institute of Multimedia Education, Tokyo. “High Frequency Sound Above the
Audible Range,Affects Brain Electric Activity and Sound Perception” Paper read at
91st. Convention of the A.E.S.October 1991. Section 7. (1), Conclusion.
2. Miland Kunchur,Depart of Physics and Astronomy, University of South Carolina.
“Temporal resolution of hearing probed by bandwidth restriction”, M. N. Kunchur,
Acta Acustica united with Acustica 94, 594–603 (2008) (http://www.physics.
sc.edu/kunchur/Acoustics-papers.htm)
3. Miland Kunchur,Depart of Physics and Astronomy, University of South Carolina.
Probing the temporal resolution and bandwidth of human hearing , M. N. Kunchur,
Proc. of Meetings on Acoustics (POMA) 2, 050006 (2008)
HOW THE 5051 COMPRESSOR WORKS
A part of the audio signal is rectied and smoothed to produce a suitable control
voltage for the VCA. 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 rst 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”, play a large part in the way a compressor sounds.
The 5051 uses very accurate, low noise, low distortion VCA having essentially no
“signature” of its own. This leaves the designer free to use amplier and transformer
combinations that are well proven and produce the desired sonic quality.
All Rupert Neve Designs modules use input and output transformers and class-A
ampliers to produce the musical “signature” for which they are known. These are
factors that enable the 5051 to work unobtrusively within the context of a very high
quality audio chain.
If the VCA control voltage is taken from the 5051 compressor input, (i.e. before
the VCA) the VCA “knows” right away that a gain change is required and there
is an almost immediate response. This is known, logically, as a “feed-forward”
compressor. If the VCA control voltage is taken from the 5051 compressor output,
(i.e. after the VCA) it cannot act immediately on the VCA because it has already
been modied by settings of the VCA and circuits through which it has passed. This

is known as a “feed-back” compressor. The two compression characteristics are quite
different, with both the attack and recovery ramps are changed. Almost all of Mr.
Rupert Neve’s earlier designs were “feed-back”.
The way in which these modes change the dynamic performance can be seen in the
above graph, but the more interesting effects are noted by listening .“Feed-Back”
produces a sweeter, warmer sound but is not as accurate if you need to protect a
transmitter, for example.
5051 Design Notes
The Shelford 5051 represents Rupert’s latest addition to the 5088 family. Comprised
of a new inductor EQ circuit with a heritage going back decades, and a compressor
with elements from the Portico II: Master Buss Processor, the 5051 can be congured
within a 5088 console to deliver exceptional tonal and dynamic control on each
channel.
Traditional transformer coupled inputs and outputs are used for both technical
performance reasons and optimum musical reproduction. The primary signal path
uses Class A gain blocks; using as few of these as possible to get the job done. The
input circuit uses one gain stage, as does the line driver output. The compressor
introduces one stage, the EQ introduces two stages, plus one more if the 18
dB / octave high pass lter is engaged. By combining this minimalisitic design
aesthetics with class-A gain blocks and custom transformers, the 5051 provides the
FF Thresh at 12 o'clock, Max Ratio
FB Thresh at 12 o'clock, Max Ratio
-20
-17.5
-15
-12.5
-10
-7.5
-5
-2.5
+0
+2.5
+5
+7.5
+10
+12.5
+15
+17.5
d
B
u
-20 +20 -15 -10 -5 +0 +5 +10 +15
dBu

extraordinary performance and musicality expected from a Rupert Neve design.
The EQ certainly invokes similarities sound-wise with some of Rupert’s classic
EQ designs from the seventies. The 5051 repeats history in using a custom tapped
inductor and carefully selected capacitor values to form the mid range equalizer
band. The 5051 also uses inductors for the low and high EQ, with the shelf curves
and frequency choices based on Rupert’s vintage designs. While this method
may not be as variable as some of Rupert’s designs of the last 20 years, the “old
ways” did have a “sound” that has become rather known and sought after. The
use of low-feedback, class-A gain blocks in each EQ section are also an important
contributor to the overall sound, preventing low level artifacts and harshness from
detracting from the tonal shaping. While these elements make the 5051 much like
many of Rupert’s vintage designs, the 5051 takes advantage of techniques that were
not possible 35 years ago, and should not be considered a clone of his earlier work.
Rather, the 5051 is a culmination of Rupert Neve’s years of experience, expertise,
and highly discerning ears, giving this unit a strong sense of Mr. Neve’s design
heritage.
Both the high and low band can be switched from shelf to peak curves and offer 15
dB of boost or cut. The high band can be switched from 8 kHz to 16 kHz, and the
low band can be 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 “Mid Hi Q” switch to narrow the bandwidth
(increase the Q) of the lter. The 5051 includes an 18 dB / octave high pass lter
with cutoff frequencies on a button that toggles through “OFF, 60 Hz and 120 Hz”
indicated by a blue or red LED respectively.
Additionally, the EQ can be switched Pre or Post the compressor. The 5051 also has
two XLR balanced inputs that can be selected from the front panel. This allows the
user to have both a mic preamplier and line input from a DAW pre-patched and
easily selectable.
The compressor likewise contains some elements of the past, utilizing Class A gain
blocks, mixed with the gain reduction techniques that have been developed over
the years and is similar to the Master Buss Processor. The threshold has a range of
-30 dBu to +20 dBu. The ratio can be set from 1.1:1 to 40:1. The attack has a range
of 5 ms to 75 ms, and the release is variable from 100 ms to 2.5 s to be set. Make-
up gain can be set from -6 dB to +20 dB.
The Compressor allows the user to select either a modern feed-forward topology or
the traditional feed-back style of compression. Each has advantages depending on
the source and desired sound. The 5051 includes a 12 dB/octave 250Hz high pass
lter that can be switched into the compressor side-chain to reduce the chance that
loud low frequency material inadvertently affects the gain reduction. There is also
a link switch and associated 1/4” phone jacks on the back panel so that multiple
5051’s can be properly used for stereo. The back panel also features a pair of 1/4”
phone jacks to patch in your own EQ into the side-chain for de-essing and nessing
the compressor response. The 5051 has two 8 segment fast acting accurate LED bar-
graph meters to indicate Gain Reduction and Output Level.

Unlike other modules for the 5088, the Shelford 5051 requires its own standalone
power supply to operate. The power supply features proprietary 4-pin polarized
outputs at +24 and -24V DC, and will power up to twenty-ve 5051 modules.
5051 Features
LINE 1 / LINE 2
Allows you to have two sources pre-patched into the 5051. For example you may
have an outboard Microphone Pre-Amp patched into Line 1 and a DAC channel
from your DAW into Line 2.
EQ IN
Engages all bands of the equalizer except the hpf.
HF
Adjusts up to 15 dB of boost or cut at selected high frequencies.
8K /16K
With the switch out, the center or corner frequency of the high band is 8 kHz. With
the button pressed, the center or corner frequency changes to 16 kHz. Between this
switch and the HI PEAK switch, you have 4 different EQ curves to nesse the high
frequency content.
HI PEAK
When the button is out, the high frequency band operates in shelf mode, boosting
or cutting above the corner frequency at approximately 6 dB/octave. Below the
corner frequency the amount of boost or cut gradually diminishes. With the HI
PEAK button pressed, the high frequency band changes to peak mode with a bell
shaped boost or cut curve. The Peak mode utilizes an inductor and capacitor circuit
to create the bell-shaped curve.
MID FREQ
The MID FREQ rotary switch has 6 positions to select the center frequency of the
mid band EQ stage. This circuit utilizes an inductor and capacitors to shape the EQ
curve, the same way as Rupert Neve’s console designs of the 70’s. The frequencies
chosen are 200 Hz, 350 Hz, 700 Hz, 1.5kHz, 3 kHz and 6 kHz. 200 Hz is
especially useful for cuts on individual tracks within a dense mix.
MID HI Q
The resonance or Q of the mid band at maximum boost is typically 2 when the
button is out. When the MID HI Q is pressed at maximum boost, the Q narrows
to approximately 3.5. The Q widens nicely with less boost or cut as is typical for
passive EQ circuits. The Q tends to be slightly wider when the frequency is set
lower, and slightly higher for higher frequency selections. The Q is also narrower
for cuts than it is for boosts and the mid band is non-symmetrical by design.
MID LEVEL
Adjusts up to 15 dB of boost or cut at the selected mid frequencies. Remember to

reduce the signal level at the source to minimize the potential for distortion when
any of the 3 bands are boosted signicantly.
EQ PRE / POST
Switches the order of the equalizer and compressor sections. With the button out,
the equalizer is before the compressor, which means that moderate changes to the
EQ settings may require some adjustment of the compressor threshold to maintain
a similar amount of compression, or make up gain to maintain a target output
level. With the switch pressed in post mode, the EQ follows the compressor. Now
moderate changes to the EQ will not affect the compressor, but one may miss
having the compressor responding to EQ settings. Also, the EQ will likely have a
greater effect on output levels, which may in turn be compensated for with the
compressor gain. Each mode has benets and drawbacks, and many engineers have
preferences as to whether they like the EQ pre or post compression.
HPF
Engages an 18 dB per octave Butterworth high pass lter to remove unwanted low
frequency sounds. This button actually allows two different corner frequencies. The
rst press selects a 60 Hz lter denoted by the light illuminating blue. The second
press selects a 120 Hz lter denoted by the button illuminating red. The third press
cycles the lter back to “off” or “bypass” which extinguishes the LED.
LOW FREQ
The LOW FREQ rotary switch has 4 positions for selecting one of four corner or
center frequencies for the low band EQ section. The frequencies are 35 Hz, 60 Hz,
100 Hz and 220 Hz.
LO PEAK
When the button is out, the low frequency band operates in shelf mode, boosting
or cutting below the corner frequency. Above the corner frequency the amount of
boost or cut gradually diminishes at approximately 6 dB/octave. With the HI PEAK
button pressed the low frequency band changes to peak mode with a bell shaped
boost or cut curve. Between the LO PEAK button and LO FREQ rotary switch, an
engineer has 8 tonal variations of EQ shapes to nesse the bottom end, plus the 2
high pass lter choices can be introduced for further tightening and manipulation.
LF
Adjusts up to 15 dB of boost or cut at the selected low frequencies. Cut can be used
as a variable, and perhaps more gentle alternative to using the HPF. Remember to
reduce the signal level at the source to minimize the potential for distortion when
any of the 3 bands are boosted signicantly.
GAIN
Adjusts the nal output level of the compressor, and is operationally the same as
“Make-Up Gain”. Gain is used to restore the signal back up to a relatively normal
level, and is often used to nely control sending the nal signal level, for example,
to an analog to digital converter.
S/C HPF
Engages a 250Hz, 12dB per octave high pass lter to prevent low frequency

material from excessively controlling the compressor. With mixes or wide spectrum
sounds, there is often signicant amounts of low frequency energy that can cause
occasional deep compression, yet it is often the mid frequency sounds that are
associated with apparent loudness and the zone that needs compression. The S/C
HPF is designed for those situations and 250 Hz is well suited for both vocals and
mixes and most other dynamic wide spectrum sounds.
ATTACK
Sets the attack time of the compressor with a range from 5ms to 75 ms. This adjusts
the rate that the compressor will reduce gain given the onset of a loud sound.
Faster settings will let the compressor respond to quick transients such as the initial
hit of a drum and reduce those hits. Slower settings may let the initial transient be
relatively untouched but may reduce the part of the drum’s decay, which tends
to exaggerate the balance of initial transient to decay. Moderate settings are most
useful for preserving the tonal balance of the source, while still effectively taming
louder sections of the music.
RELEASE
Sets the release time of the compressor with a range of 100 ms to 2.5 s. When the
source signal drops below the threshold after being engaged, the release determines
how fast the gain returns to normal. Faster settings tend to be most useful for
maximizing loudness, however, there is a greater chance if audible compression,
including “pumping” and a slight modulation distortion in the presence of loud low
notes. Medium settings are sometimes nice for having the compression act in time
with the music. Slow release settings tend to be the least audible and most safe,
which may also be said about using lower Ratios, and less compression.
LINK
Allows multiple 5051 modules to be linked together such that at any given time,
the 5051 with the highest control voltage will control the compression of all the
linked units. To create a stereo pair, rst adjust the two modules so that they have
identical compression and EQ setting. Then engage the link switch on the front of
the left-most 5051.
FF / FB
Selects either feed-forward or feed-back modes of compression. Feed-forward
uses the input signal to trigger compression, and feed-back uses a signal from after
the gain change element to trigger compression. Feed-forward is often associated
with modern compressors and feed-back was generally the method of vintage
compressors. Feed-forward typically allows for high ratios, tends to be faster and
may offer more dramatic compression effects. Feed-back is often considered to be
more traditional, softer, gentler and smoother.
RATIO
Adjusts the ratio of compression above the threshold. The range is from 1.1 to 1 up
to 40:1 (in FF mode). Ratio is related to the input signal over the threshold versus
the output signal. Lower ratios mean that loud sounds will only cause slight gain
reduction and high ratios can cause deep amounts of gain reduction. For example,
consider a voice that gets louder than the a threshold by 10 dB, 10:1 will only let

the output rise by 1 dB implying 9 dB of compression, 2:1 will cause the output
to increase 5 of those initial 10 dB suggesting 5 dB of reduction. Some engineers
relate ratios of 20:1 and higher with limiting, however technically traditional
limiting also requires very fast attack times to respond to transients and prevent
signals from actually going above a certain level.
COMP IN
Engages the compressor, and is indicated by a green button. Other than simply
engaging the compressor, engineers often toggle this button to aid adjusting
the make-up gain for similar average levels. The comp in button is also used to
compare the untreated signal to the compressed signal to verify a positive change is
being made.
THRESHOLD
Sets the level where the compressor begins to react and respond to signals above
the set threshold. With the knob set clockwise, only extremely loud signals might
cause any gain reduction. With the knob set counter-clockwise, even relatively
quiet sounds can cause compression.
GR METER
Indicates how many dB’s of gain reduction are happening at a given time. This
particularly aids in choosing threshold and ratio settings. While the GR meter is
great to conrm what we think we are hearing, usually our listening skills provide
a more direct path to choosing compressor settings than meters. The meter will
generally indicate very brief gain reductions but will tend to exaggerate the
duration so that the eye can see transient compression.
LEVEL METER
Displays the nal peak output level of the 5051 regardless of whether the unit is
set for EQ PRE or POST. This meter assists adjusting the compressor gain, and helps
prevent equipment that the 5051 may be feeding from clipping or overloading.
In the case of A to D converters, one should primarily depend on the converters
own meters due to possible converter calibration variables. The 5051 level meter
is calibrated for dBu, and the red LEDs may not necessarily match up with the
destination device. It is often advisable to maintain levels 10 to 20 dB below the
destination’s maximum input for ease of later processing.
S/C INSERT SND
A 1/4” unbalanced phone jack used to send the signal to an external device,
primarily EQ, to create a key signal (it can be any old EQ or device since the
audio isn’t effected). For example, you may EQ the signal, cutting all the lows and
boosting somewhere between 5 kHz and 8 kHz to cause the compressor to respond
to frequencies associated with sibilance, and become a de-esser. An engineer
can also gently reduce lows and increase mid highs so that the compressor may
respond similarly to how our ears may perceive apparent loudness.
S/C INSERT RET
A 1/4” phone unbalanced input jack that is receives the signal from the external

device described above. The S/C insert return may also be used as a key input.
For example, an engineer might wish to patch in a kick drum to control the
compression happening on a bass guitar being run through the 5051.
IMPORTANT NOTE: The S/C insert return is a half-normal connection, meaning that
if a plug is inserted into the jack, it will interrupt the S/C signal path, and whatever
signal is present on the plug will now be the controlling the compressor side-chain,
i.e., if there is no signal present on the plug, there will be no compression.
LINK IN / OUT
1/4” phone jacks on the back used to connect the compressor VCAs.
The suggested setup for linking multiple units is to do the following:
On the back panel of the left most 5051, plug the link cable into the link out jack.
Plug the other end of the cable into the link in jack of the 5051 to its right. In the
same way, connect all of the 5051 units together.
LINE 1
XLR female transformer balanced oating input associated with the LINE 1 position
of the front panel input switch. Pin 2 high, 10 k Ohm input impedance.
LINE 2
XLR female transformer balanced oating input associated with the LINE 2 position
of the front panel input switch. Pin 2 high, 10 k Ohm input impedance.
OUTPUT
XLR male transformer coupled oating output. Pin 2 high, less than 50 Ohm output
impedance.
POWER
Proprietary 4 pin polarized input for +24 and -24V DC power input. There are
currently 5-way and 25-way supplies available.
Specifications
Line In
Frequency Response:
Main Output, no load,
–3 dB @ 2.5 Hz
–3 dB @ 125 kHz
Noise:
Measured at Main Output, unweighted, 22Hz-22kHz,
Terminated 40 Ohms, With gain at unity
better than –102 dBu
Maximum input:
from 20 Hz to 20 kHz,
+25 dBu.
Maximum output:

from 20 Hz to 20 kHz is +25 dBu.
Total Harmonic Distortion and Noise:
from <10 Hz to 80 kHz,
@ 1kHz, +20 dBu output: Better than 0.002%
@ 20Hz, +20 dBu out Better than 0.120%
@ 20kHz, +20 dBu out Better than 0.010%
Equalizer
Noise:
Measured at Main Output, unweighted, 22Hz-22kHz,
Terminated 40 Ohms. with all gains set at 0,
Better than –92 dBu
Maximum input:
from 20 Hz to 20 kH,
+24.5 dBu
Maximum output:
from 20 Hz to 20 kHz,
+24.5 dBu
Total Harmonic Distortion and Noise:
from <10 Hz to 80 kHz,
@ 1kHz, +20 dBu output: Better than 0.007%
@ 20Hz, +20 dBu out Better than 0.120%
@ 20kHz, +20 dBu out Better than 0.070%
The Compressor
(Threshold at +20 dB, Ratio at 1.1:1, Gain at 0)
Noise:
Measured at Main Output, unweighted, 22Hz-22kHz,
Terminated 40 Ohms.
Better than –92 dBu
Maximum input:
from 20 Hz to 20 kHz,
+25 dBu.
Maximum output:
from 20 Hz to 20 kHz,
+25 dBu.
Total Harmonic Distortion and Noise:
from <10 Hz to 80 kHz
@ 1kHz, +20 dBu output: Better than 0.020%
@ 20Hz, +20 dBu output Better than 0.140%
@ 20kHz, +20 dBu output Better than 0.070%
Threshold:
Continuously Variable from -30dBu to +20dBu
Ratio:
Continuously Variable from 1.1:1 to 40:1

Gain:
Continuously Variable from -6 dB to +20 dB
Attack:
Continuously Variable from 20 mS to 75 mS
Release:
Continuously Variable from 100mS to 2.5 Seconds
Low Frequency EQ
ColorSweep Trace Comment
1 1 Red EQ Flat
2 1 Cyan 35 Hz Full Boost
3 1 Cyan 35 Hz Full Cut
4 1 Green 60 Hz Full Boost
5 1 Green 60 Hz Full Cut
6 1 Magenta 100 Hz Full Boost
7 1 Magenta 100 Hz Full Cut
8 1 Red 220 Hz Full Boost
9 1 Red 220 Hz Full Cut
-20
+20
-15
-10
-5
+0
+5
+10
+15
d
B
u
10 200k
20 50 100 200 500 1k 2k 5k 10k 20k 50k
Hz

ColorSweep Trace Comment
1 1 Red Flat
2 1 Magenta 8K Shelf Full Boost
3 1 Magenta 8K Shelf Full Cut
4 1 Cyan 16K Shelf Full Boost
5 1 Cyan 16K Shelf Full Cut
6 1 Green 8K Peak Full Boost
7 1 Green 8K Peak Full Cut
8 1 Red 16K Peak Full Boost
9 1 Red 16K Peak Full Cut
-25
+25
-20
-15
-10
-5
+0
+5
+10
+15
+20
d
B
u
10 200k
20 50 100 200 500 1k 2k 5k 10k 20k 50k
Hz
Color
Sweep Trace Comment
1 1 Red Flat
2 1 Magenta 200 Hz Full Boost
3 1 Magenta 200 Hz Full Boost Hi Q
4 1 Magenta 200 Hz Full Cut
5 1 Magenta 200 Hz Full Cut Hi Q
6 1 Cyan 350 Hz Full Boost
7 1 Cyan 350 Hz Full Boost Hi Q
8 1 Cyan 350 Hz Full Cut
9 1 Cyan 350 Hz Full Cut Hi Q
-25
+20
-20
-15
-10
-5
+0
+5
+10
+15
d
B
u
10 200k 20 50 100 200 500 1k 2k 5k 10k 20k 50k
Hz
High Frequency EQ
Mid Band EQ

PRODUCT WARRANTY
Rupert Neve Designs warrants this product to be free from defects in materials and
workmanship for a period of one (1) year from date of purchase, and agrees to rem-
edy any defect identied within such one year period by, at our option, repairing or
replacing the product.
LIMITATIONS AND EXCLUSIONS
This warranty, and any other express or implied warranty, does not apply to any
product which has been improperly installed, subjected to usage for which the
product was not designed, misused or abused, damaged during shipping, damaged
by any dry cell battery, or which has been altered or modied in any way. This
warranty is extended to the original end user purchaser only. A purchase receipt or
other satisfactory proof of date of original purchase is required before any warranty
service will be performed. THIS EXPRESS, LIMITED WARRANTY IS IN LIEU OF
ALL OTHER WARRANTIES, EXPRESS OR IMPLIED, TO THE EXTEND ALLOWED
UNDER APPLICABLE STATE LAW. IN NO EVENT SHALL RUPERT NEVE DESIGNS
BE LIABLE FOR ANY SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
RESULTING FROM THE USE OF THIS PRODUCT. Some states do not allow the
exclusion or limitation of consequential damages or limitations on how long an
implied warranty lasts, so this exclusion may not apply to you.
WARRANTY SERVICE
If you suspect a defect in this product, please call us at 512-847-3013 or email us
at [email protected] to discuss the suggested defect (it is possible that a sus-
pected defect could be due to improper usage) and to obtain a return authorization
number. It shall be your responsibility to pay for shipping the product to us, and, if
the product is determined to be defective, our responsibility to pay for shipping the
product back to you.
Rupert Neve Designs
PO Box 1969
Wimberley TX 78676
www.rupertneve.com
tel: [phone]
fax: [phone]
5051 Manual Rev D: P/N 77500014