Cedar DNS 4 User manual

DNS 4 dialogue noise suppressor
OWNER’S MANUAL
© 2022 CEDAR Audio Ltd
Manual version 1.00 September 2022

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Table of Contents
Introduction to the DNS 4 ................................................................................ 5
Safety instructions ........................................................................................ 6
Setting up the DNS 4 .......................................................................... 7
The front panel .......................................................................................... 12
The process page ........................................................................................ 14
The channel setup page ................................................................................ 16
The global setup page .................................................................................. 17
Using the DNS 4 .............................................................................. 19
Processing ................................................................................................ 20
Summary of operation .................................................................................. 22
Additional information ...................................................................... 23
Declaration of conformity ............................................................................. 25
3rd-party Licence ....................................................................................... 26
Contact information .................................................................................... 27
Specifications ............................................................................................ 28
Licence and limited warranty ......................................................................... 30

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Introduction to the DNS 4
The DNS 4 is a further development of the DNS technology introduced in our Academy
Award® winning DNS1000 and subsequent dialogue noise suppressors. Despite offering
four channels of noise suppression, it is small, light and portable, and its slick user-
interface allows users to obtain optimum results almost instantly and with the minimum
of effort. It also retains the near-zero latency of its predecessors and, with its 4-pin
12VDC power socket, it’s suitable for use in all live situations - not just on location and
for live-to-air broadcasting, but also for live sound in venues such as theatres, concert
halls, conferences venues, and places of worship.
Quality, speed and simplicity were paramount considerations when designing the DNS 4,
which offers the following:
■ Near zero latency
Its low latency ensures that there is no loss of lip-sync.
■ Flexibility
It’s able to handle a wide range of noise suppression requirements.
■ Speed and ease of use
Its carefully designed user-interface maximises speed and ease of use.
■ 12VDC power
It accepts power from industry standard adapters and power packs for use anywhere in
the world.
■ Powerful processors
The latest technology to ensure that it will handle the most complex processing
requirements.

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Safety instructions
Read these instructions, and follow them.
■ Water and moisture
The DNS 4 must not be exposed to rain or moisture. Furthermore, if it is brought directly
from a cold environment into a warm one, moisture may condense inside it. This, in
itself, will not cause damage, but may cause electrical shorting. This could damage the
unit, and even cause danger to life. Always allow the unit to reach ambient temperatures
naturally before connecting the mains power.
■ Mounting and ventilation
You should place the DNS 4 on a flat, stable surface or in a suitable equipment bag. Do
not subject it to strong sunlight, excessive dust, mechanical vibration or periodic shocks.
It is not susceptible to excessive heat build-up, but should be installed away from heat
sources such as radiators and audio devices that produce large amounts of heat.
■ Power sources
The DNS 4 operates on nominally 12VDC power, although it will operate on voltages in
the range from 8V – 17.5V. You should route power cables so that they will not be walked
on or pinched. Unplug the supply cord to isolate the external PSU from the mains supply
if it is not to be used for some time. Grasp the supply cord by the plug, never by the cord
itself.
■ Connections
Turn off the power to all equipment before making any connections. In order to comply
with EMC regulations, you must use metal-shelled connectors and good quality shielded
cable suitable for AES3 connections.
■ Cleaning
Clean the DNS 4 only with a dry cloth. Never use abrasive pads, water or liquid cleaners
such as alcohol or benzene.
■ Damage requiring service
The DNS 4 contains no user-serviceable parts and should on no account be opened or
dismantled by unauthorised personnel. A unit should be returned to qualified service
agents when it has been exposed to liquids, when it fails to function correctly, when it
has been dropped, or when the case is damaged.

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Setting up the DNS 4

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Unpacking
Unpack the DNS 4 carefully. Save the carton and all packing materials since you may need
them to transport the unit in the future. In addition to the DNS 4 and its packaging, the
box should contain the following:
• 12V DC power supply
• start-up and safety instructions sheet
• a warranty registration card
To maintain reliability and prolong operating life, observe the following environmental
considerations:
• the temperature should be maintained between 5 and 30 Celsius
• relative humidity should be in the range 30% to 80% non-condensing
• strong magnetic fields should not exist nearby.
Power source
A 12V PSU is included with the DNS 4 and this will work on any mains supply in the range
85V to 250V, 50/60Hz AC. Connect its output to the DNS 4 power input and then plug it
into the mains supply.

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Audio setup
The audio connectors are on the sides of the unit; analogue inputs are on the left, while
analogue outputs and all digital I/O are on the right side. Connections of a similar
function are grouped together, with the low channel numbers within each group towards
the rear of the unit.
■ Inputs
There is a single global user control to switch between analogue or digital inputs. (See
Global setup.)
When analogue inputs 1&2 are in use, a pair of three-position switches select between
line, microphone and microphone with +48V phantom powering for each of these
channels.

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■ Outputs
The first two output sockets are dedicated analogue line outputs for channels 1&2. The
next two are dual-purpose and can carry either analogue or digital signals according to
the user setup option. (See Global setup.)
All of the outputs are active when any analogue I/O is selected. When digital operation is
selected for both the inputs and the outputs, the analogue circuitry is turned off to save
power and the Line 1 and Line 2 outputs are not operational.
■ Audio clock
A single audio clock is used for the DSP, ADC, DAC and AES3 transmitter. When analogue
I/O is used, the internal 48kHz clock is used. When AES3 input 1&2 is connected, the
clock is derived from that source. Operation at 44.1kHz, 48kHz and 96kHz is supported.
USB
There is a USB socket for updating the firmware. You can also obtain this manual from
the DNS 4’s internal storage via USB.

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The front panel
The DNS 4 front panel is divided into three sections: a set of three fixed-function buttons
to the left, an OLED screen, plus six context-sensitive buttons and an encoder to the
right.
The screen dims to a lower brightness after a few seconds of inactivity, and returns to
full brightness when any control is operated.
Pages
There are three control pages, and the functions of the context-sensitive controls depend
on which is active:
Process
The main page displays control and status information about the processing.
Channel setup
Allows access to options that are specific to a given channel.
Global setup
Allows access to unit-wide options, and also displays static information about the unit.
Fixed-function buttons
■ Power/lock
The DNS 4 switches on automatically when power is applied and displays the Process
page. This guarantees that it reboots after a power failure. The Power/lock button is
illuminated while the unit is powered on.

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Once the DNS 4 is powered up, you can press the Power/lock button a second time to
lock the panel. When it’s locked, the Power/lock and Setup buttons continue to operate,
but all the other controls are disabled. Hold down the Power/lock button for around
three seconds to unlock the panel.
When the panel is unlocked, you can switch the DNS 4 off by pressing and holding the
Power/lock button for around three seconds. The current settings will be stored during
shutdown and will be recalled when the unit is turned on again. If the unit is not shut
down correctly, the settings may not be stored.
The DNS 4’s current settings are also stored a few seconds after you stop adjusting the
controls.
Should something cause the unit to freeze, you can switch it off by a holding the
Power/lock button for approximately six seconds.
■ Setup
The Setup button cycles through additional pages to access the setup parameters. It’s
illuminated when the unit is displaying pages other than the Process page.
■ Bypass
The Bypass button acts as a global process on/off control. When active, it’s illuminated
and the noise reduction process is disabled on all four channels. The input gain and high-
pass filter (see Channel setup) are unaffected by the bypass state.
It offers two actions:
Short press
Toggles between bypass on and off
Long press
When bypass is off, pressing and holding the button acts as a preview, switching bypass
on for as long as the button is held. Then, when released, bypass returns to the off state.

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The process page
The DNS 4 boots into the Process page and returns to it from any other page after a short
timeout. This displays information about all four channels simultaneously.
■ Input level meters
The left of the display shows input level meters for each of the four channels. These are
for information only; the input gain controls are available in the Channel setup page.
■ Process readouts
The rest of the display shows the process settings for each of the four channels. The
information shown for each channel is:
• the noise Attenuation
• the Bias
• the linking status
Channel linking
You can link certain combinations of channels into groups. Grouping channels makes
them adopt identical settings, and allows you to adjust them together. The channels in a
group share the same values of the following parameters:
• input gain
• high-pass filter on/off
• processing on/off
• learn on/off
• Attenuation
• Bias
Nonetheless, the Learn function continues to work independently for each channel in a
group and the signal processing itself is not linked. This ensures that, if the parameters
are appropriate, the processing is appropriate for the signal in each channel.

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The permissible combinations of groups are as follows:
Channels:
1
2
3
4
Independent
-
-
-
-
First pair linked
1&2
-
-
Second pair linked
-
-
3&4
Two pairs linked
1&2
3&4
All linked
1&2&3&4
You create a group by pressing simultaneously the channel selection buttons for the first
and last channels to be included in it. Pressing the same pair of buttons again destroys
the group and the channels return to being independent.
When a group is created, the process parameters from the lowest-numbered channel in
the new group are copied to the other channel(s) in the group. No process parameters
are changed when a group is destroyed.
Groups can be created and destroyed on both the Process page or the Channel setup
page; the operation is identical in both cases. Note that the channel linking/grouping
operates independently of split mode. (See Global setup.)

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The channel setup page
Pressing Setup once accesses the Channel setup page.
■ Digital inputs selected (see Global setup)
If digital inputs are selected, the page displays:
• the input source for the active channels (see Global setup)
• the high-pass filter status for each channel
• the linking status
The unit will lock to any AES3 signal with a nominal sample rate of up to 96kHz that is
presented to its inputs. Operation is supported at 44.1kHz, 48kHz and 96kHz.
■ Analogue inputs selected (see Global setup)
When the analogue inputs are used, a second vertical display is shown for each channel.
This is the input gain, and you adjust this by selecting the appropriate channel and
turning the encoder.
Note that, if channel 1 is set to MIC or 48V and channel 2 is set to LINE (or vice versa)
their gain and high-pass filter settings remain independent, even if channels 1 and 2 are
linked.
■ High-pass filter
An 80Hz, -18dB/oct high-pass filter is available for each input. To toggle this on and off
for any channel, press any of the row of four channel access buttons at the top right of
the unit to bring its associated channel (or group) into focus. When a channel is in focus,
the dns on button toggles the high-pass filter.
An icon in each channel display will show whether the filter is active or not .

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The global setup page
Pressing Setup a second time takes you to the Global setup page. There are three
parameters, each of which has two possible settings.
■ Inputs
Select the analogue or digital inputs. If the input selection is set to digital and no valid
digital signal is present at the digital input, a flashing cross will appear inside the AES1/2
or AES3/4 fields and the DNS 4 will not process audio.
■ Routing: Split mode operation
In split mode, the signals presented to inputs 1&2 are duplicated and sent to channels
3&4. This allows inputs 1&2 to be processed and output in two different ways, including
outputting the duplicate pair without processing to create ‘iso’ tracks.
■ Outputs 3 & 4: analogue line or AES3 digital
Select whether outputs 3&4 carry line level analogue or digital signals. The input/output
selections operate as follows:
Input
Output
Output 1
Output 2
Output 3
Output 4
1
Analogue
Analogue
Line 1
Line 2
Line 3
Line 4
2
Analogue
Digital
Line 1
Line 2
AES 3 1&2
AES 3 3&4
3
Digital
Analogue
Line 1
Line 2
Line 3
Line 4
4
Digital
Digital
-
-
AES 3 1&2
AES 3 3&4

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Principal uses:
1: integrates the DNS 4 into an analogue system
2: allows the DNS 4 to be used as a mic pre as well as a processor within an otherwise
digital system
3: allows you to output analogue signals from a digital system
4: is digital-to-digital and all the analogue I/O is switched off to save power.
Press setup again or wait for the timeout to return to the Process screen.

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Using the DNS 4

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Processing
When you are in the Process page, pressing any of the row of four channel access buttons
at the top right of the unit brings its associated channel into focus. Once a given channel
has focus, its associated button is lit and you can adjust its parameters. Channels can
also be grouped and their parameters adjusted together.
The process is controlled by an encoder plus dedicated buttons for process on/off and
learn on/off. Normally the encoder is focused upon the Attenuation parameter. Clicking
it switches its focus to the Bias parameter, and a second click returns it to the
Attenuation. The encoder focus also reverts to Attenuation after a short timeout.
■ Process On/Off
Use the dns on button to switch the DNS processing on and off.
■ Learn
The Learn button controls whether or not the noise detector adapts continuously to
changes in the noise content within the audio signal. When it’s On, the DNS 4 continually
identifies the power and spectral distribution of the noise. When it’s Off, the noise
estimate is frozen at the last determined values and remains so until it’s switched on
again.
Note: Learn is not a method for taking a ‘noise fingerprint’ and, for most jobs, by far
the best results are obtained by leaving it switched on permanently.
■ Channel selection
Before adjusting anything further, use the channel selector buttons 1- 4 to select the
individual channel or, if linked, the group of channels that you wish to control.
The process parameters
■ Attenuation
The default action of the encoder is to adjust the amount of noise attenuation applied to
the signal in the selected channel(s). The representation of the left-hand fader within
each channel shows the current position of the control, and the bargraph shows the
instantaneous amount of attenuation being applied to the signal. The solid bar shows the
average attenuation across all frequencies, and the shaded bar shows the maximum
attenuation across all frequencies.