Neve 2254/R User manual

2254/R
Limiter Compressor
User Manual
527 - 386
Issue 2.3
The 2254/R Limiter Compressor has been designed specifically for the
sound recording industry, for the control of programme dynamics.
It is based on the classic 2254 series, originally released in 969.

2254/R Limiter Compressor Issue 2.3
Health Safety Notice
For your own safety and for the protection of others,
please observe the following safety precautions:
•Read these instructions.
•Heed all safety warnings.
•Do not use near water.
•Clean only with a dry cloth.
•Do not install near heat sources.
•Do not block ventilation openings.
•Protect the power cord.
•Only use accessories specified by the manufacturer.
•Unplug when unused for long periods of time.
•Refer all servicing to qualified personnel only.
AMS NEVE
Billington Road
Burnley
Lancs
BB 5UB
England
Phone [phone]
Fax: [phone]
Email: [e-mail]
Web: www.ams-neve.com
Support: http://www.ams-neve.info/crm/fault_report.html
In the unlikely even that this unit should malfunction or develop a fault, then please register
the fault details on our website, by clicking the link below.
You will also need to enter the unit's serial number when you do this, so please have this to
hand.
http://www.ams-neve.info/crm/fault_report.html
Once the fault details have been registered, one of our technical support team will be in touch
via email.
This link should also be used for further operational or technical help, or any general enquiry
about the unit.
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2254/R Limiter Compressor Issue 2.3
Table of Contents
Health Safety Notice
Introduction
Principles of Operation............................................................................................4
Recall Software......................................................................................................4
Front Panel Controls
Power...................................................................................................................5
In.........................................................................................................................5
Link......................................................................................................................5
Limiter section...........................................................................................................6
Limit.....................................................................................................................6
Limit Level.............................................................................................................6
Limit Recovery.......................................................................................................6
Fast Attack............................................................................................................6
Fast Attack Time....................................................................................................6
Compress section.......................................................................................................7
Compress..............................................................................................................7
Compress Ratio......................................................................................................7
Compress Threshold...............................................................................................7
Gain Make Up........................................................................................................7
Compress Recovery................................................................................................7
Meter........................................................................................................................8
Rear Panel
Line Input..............................................................................................................9
Output..................................................................................................................9
Set Gain................................................................................................................9
Sidechain Link........................................................................................................9
Power DIN socket................................................................................................. 0
Fuse.................................................................................................................... 0
USB.................................................................................................................... 0
Technical Earth..................................................................................................... 0
Chassis............................................................................................................... 0
Recall Software
Installation for PC.................................................................................................
Installation for Mac............................................................................................... 3
Firmware Upgrade
Selecting a File for Transfer................................................................................... 4
File Downloading.................................................................................................. 5
Corrupted or Old Firmware.................................................................................... 5
Unit Specifications
General............................................................................................................... 6
Limiter................................................................................................................ 6
Compressor......................................................................................................... 6
Meter.................................................................................................................. 6
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2254/R Limiter Compressor Issue 2.3
Introduction
The 2254/R Limiter Compressor is a sophisticated and powerful tool for
the control of programme dynamics, and has been designed specifically
for the sound recording industry.
To this end, considerable range of control is provided within a small unit
whilst adhering to high standards of performance.
It is based on the classic 2254 series originally released in 969.
Principles of Operation
A single control element is used, capable of some 50dB of gain change
with low distortion and noise.
This element is driven by two independent sidechains – one of which acts
a limiter and the other which acts as a compressor.
Each of these functions operates in a closed loop and may be used in
isolation or together.
•The Compressor sidechain samples the programme level before the
output line amplifier, thus enabling make-up gain to be provided
where necessary.
A series of shaping networks are employed to yield five different
compression ratios and by controlling the effective sidechain gain, the
threshold may be varied over a wide range.
•The Limiter sidechain samples the line amplifier output and thus
controls the absolute limit of the programme.
A variety of time constants are available to suit the nature of the
programme.
Where two 2254/R units are used together to control the left and right
signals of a stereo programme, the control voltages from the two
sidechains may be linked to ensure that no shift in image takes place.
Recall Software
All of the switches and settings on the unit can be recalled for later reset
using the Recall software.
The settings of up to 6 units can be stored and recalled in this way using
either discrete USB ports on your computer (or Mac) with one per unit, or
using a powered USB hub.
All soft switches are instantly recallable using a single mouse click, while
rotary controls are reset manually by matching them to on-screen
graphics.
The Recall software is the same as that which is used for the 88 series of
Neve outboard units (880 , 8803, 8804 and 88 6).
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2254/R Limiter Compressor Issue 2.3
Front Panel Controls
Power
The Neve logo switch to the left of the meter switches the unit on and off.
The button will light red when the unit is on.
In
Lights yellow when selected, and sends the signal through the units
circuitry, even if the unit does not have the Limit or Compress functions
selected.
The unit constitutes a buffer amplifier having high input and low output
impedance.
If unlit, the Input XLR on the rear of the unit is connected directly to the
Output XLR i.e. the unit is bypassed.
Link
Lights yellow when selected.
Press this button when you wish to link two 2254/R units together so they
can process the Left and Right of a stereo signal, first making sure that
the 9-pin Link sockets on the rear of both units are connected together.
See pin-outs information on page 8.
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2254/R Limiter Compressor Issue 2.3
Limiter section
Limit
Lights yellow when selected, and switches the Limiter sidechain in and out
of circuit.
Limit Level
May be set in steps of 2dB from +4dBu to +20dBu.
Limit Recovery
There are three preset recovery times ( 00ms, 200ms & 800ms), plus an
automatic setting (AUTO).
In the AUTO position, both the Attack and Recovery times are composite
and self-adjusting.
Speeds are rapid for isolated peaks, while remaining slow for persistently
high levels, so the impression of a normal dynamic range is preserved as
the programme rides on a slowly moving 'gain platform'.
Fast Attack
Lights yellow when selected.
When unlit, the unit has a much slower attack time (5mS), so as to avoid
unpleasant effects when processing signals of a percussive nature (such
as solo piano).
In this way, a narrow dynamic range may be achieved by feeding high
levels into the 2254/R and choosing a low limit level.
Fast Attack Time
When FAST ATTACK is selected, the attack time can be set from 00µS
to 2mS using the associated rotary control.
This control is continuously variable and is fully sweepable between those
two values.
If FAST ATTACK is unlit, this control has no function.
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2254/R Limiter Compressor Issue 2.3
Compress section
Compress
Lights yellow when selected, and switches the Compressor sidechain in
and out of circuit.
Compress Ratio
Five preset ratios are provided.
•.5:
•2:
•3:
•4:
•6:
The control characteristic is shaped such that the onset of compression is
smooth and progressive, the true ratio being reached within the first 5 to
0dB above the Threshold.
Compress Threshold
The Threshold point can be varied in 2dB steps from -20dBu to + 0dBu,
thus a wide variety of effects can be achieved.
Low Ratios operated with a low Threshold will preserve the dynamic range
and also achieve a high signal to noise ratio.
A high Ratio with a high Threshold will behave as a partial limiter.
Gain Make Up
When a Threshold point below line level is chosen, it is necessary to add
gain beyond the compressor so as to restore the mean programme level.
The gain control provides up to 20dB of additional gain in 2dB steps.
Compress Recovery
Three presets are provided:
•00 mS
•200 mS
•800 mS
plus an AUTO setting.
In the AUTO position, both the Attack and Recovery times are composite
and self-adjusting.
Speeds are rapid for isolated peaks, while remaining slow for persistently
high levels, so the impression of a normal dynamic range is preserved as
the programme rides on a slowly moving 'gain platform'.
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2254/R Limiter Compressor Issue 2.3
Meter
The programme meter is operated by a simple drive circuit with rapid
attack and slow decay times, that correspond to the typical PPM
characteristic.
The green led to the right side of the meter will light at a threshold of
about - 0dBu.
The led turns red when the program reaches a level of +25dBu, indicating
imminent clipping.
The meter can be set to display either the Input signal level (In), Output
signal level (Out) or the amount of gain reduction applied to the signal by
the compressor and limiter in total (Control).
This selection is set by the adjacent Meter knob.
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2254/R Limiter Compressor Issue 2.3
Rear Panel
Line Input
Input XLR.
Pin 1 Screen
Pin 2 Hi
Pin 3 Low
Output
Output XLR.
Pinouts as above.
Set Gain
This trim pot allows you to set the overall gain of the unit to be 0dB in and
0dB out.
This is useful if, for example, the load of the unit connected to the Output
is 600Ω.
This would mean the level of the unit would drop by about dB, so the
Gain Trim allows you to compensate for this.
The default factory setting is 0dB in, 0dB out, with a load of 00kΩ.
Sidechain Link
Links the sidechains of two or more 2254/R units so that they can all work
with reference to the same sidechain.
Unit 1 Unit 2 Unit 3
For example, when each unit is processing the Left and Right of a stereo
image, this prevents sudden and unexpected changes to one side of the
image, so the stereo image is maintained.
This link carries the total of the compressor and limiter sidechains, and
the compressor with the highest amount of gain reduction will apply it's
gain reduction to the others.
Care must be taken when wiring these connectors, and the pins should
never be shorted to Ground, to the unit chassis, or to each other.
These 9-pin connectors should only ever be inserted into
(or removed from) the unit with the power OFF.
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2254/R Limiter Compressor Issue 2.3
Power DIN socket
The unit requires 36v DC, and this 8 pin DIN socket should only be
connected to the power supply provided with the 2254/R.
It is not possible to insert the power connector into this socket incorrectly.
Please refer to the adjacent diagram for connector orientation.
Fuse
A T .0 amp LBC fuse is fitted.
In the event of the unit failing to power up, this fuse should always be
checked first.
The fuse should always be replaced with one of the same value.
USB
The USB socket is a Type B connector used to connect the 2254/R to a PC
or Mac for storing & recalling unit settings.
Technical Earth
The grounding of the unit can be set in two different ways:
With this switch in the Off position the chassis of the unit is connected to
the mains earth via the power supply.
With the switch in the On position the chassis of the unit should be
connected to the studio technical earth using the adjacent Chassis
connector.
For safety reasons the chassis is NOT disconnected from the mains Earth
but is connected through a resistor capacitor filter.
Chassis
Connect this to your studio earth, and switch Technical Earth On.
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!! WARNING !!
Connections to
technical earth and
changes to grounding
should only e carried
out y qualified
personnel.