Cedar DNS1000 User manual

CEDAR
DNS1000
dynamic noise suppressor
OWNER’S MANUAL
© 2000 CEDAR Audio Ltd
Manual version 1.00: August 2000

TABLE OF CONTENTS
INTRODUCTION ..............................................................1
SAFETY INSTRUCTIONS ................................................2
SETUP ..............................................................................3
AUDIO CONNECTIONS AND INDICATORS....................4
FRONT-PANEL INDICATORS AND CONTROLS ..............5
OPERATING THE DNS1000 ............................................7
CASE STUDIES ................................................................9
Case 1: Traffic noise and other ambient sound ..................9
Case 2: Tape hiss ..............................................................11
Case 3: Excessive reverberation ......................................12
SPECIFICATIONS ..........................................................13
EMC REGULATIONS......................................................13
LICENCE AND LIMITED WARRANTY ............................14

PAGE 1
INTRODUCTION
Thank you for purchasing this CEDAR DNS1000 Dynamic Noise Suppressor.
Quality, speed and simplicity are paramount considerations in the DNS1000 design,
and its features include the following:
■Near zero latency
The DNS1000 has a group delay of less than 10 samples (typically less than
1/200th of a frame) so there is no loss of lip-sync caused by its use.
■Flexibility
The DNS1000 will handle a wide range of noise suppression requirements.
■Speed and ease of use
The DNS1000 offers a carefully designed control surface that maximises
operator comfort and speed of use.
■Audio interfaces
The DNS1000 incorporates a 24-bit digital audio interface conforming to
both AES/EBU and SPDIF standards.
■Power requirements
Its universal power supply means that a DNS1000 will work anywhere in
the world.
■Dual processors
A pair of 40-bit floating point DSP processors deliver 120MFlops so that the
DNS1000 will handle the most complex processing requirements.

PAGE 2
SAFETY INSTRUCTIONS
Read these instructions, and follow them.
■Water and moisture
The unit must not be exposed to rain or moisture. Furthermore, if the unit 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 DNS1000 to reach ambient temperatures naturally
before connecting the mains power.
■Mounting and ventilation
You should place the DNS1000 on a flat, stable surface. Do not subject it to
strong sunlight, excessive dust, mechanical vibration or periodic shocks.
The DNS1000 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 DNS1000 features a universal power supply that will work safely on any
mains supply in the range 85V to 260V, 50Hz or 60Hz AC only. The unit
should always be grounded (‘earthed’), and you should route power cables
so that they will not be walked on or pinched.
■Connections
Turn off the power to all equipment before making any connections.
■Cleaning
Clean the unit only with a dry cloth. Never use abrasive pads or liquid
cleaners such as alcohol or benzene.
■Damage requiring service
The DNS1000 contains no user-serviceable parts and should on no account
be opened or dismantled by unauthorised personnel.
It 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.

SETUP
Unpacking
Unpack the DNS1000 carefully. Save the carton and all packing materials since
you may need them to transport the unit in the future. In addition to the DNS1000
and the packaging, the carton should contain the following:
■mains connection lead
■this manual
■a warranty registration card.
Installation site
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.
Brightness control
You can adjust the brightness of the front panel indicators (buttons and Activity
LEDs) to suit local lighting conditions:
■with power OFF press and hold Bypass
■continue to hold Bypass and turn the power ON
■adjust the brightness using the Level control
■release Bypass.
This setting is stored in non-volatile memory and will be recalled when you next
use the DNS1000
PAGE 3

AUDIO CONNECTIONS AND INDICATORS
Connections
The DNS1000 offers two audio connection standards. It passes its signal to both
outputs irrespective of the input used. The standards are:
■Digital SPDIF format
■Digital AES/EBU format
The DNS1000 is not affected by channel status data. It will echo any such data
directly to the outputs.
Indicators
The DNS1000 rear panel offers two pairs of LED indicators. The upper pair display
information relating to audio signal sample frequencies. The lower pair show
which input is in use.
■Frequency LEDs
If the “44” LED is lit, the input sample rate is 44.1kHz. If the “48” LED is lit, the
input sample rate is 48kHz. If both LEDs are lit, the input sample rate is 32kHz.
If one or both LEDs are flashing, the DNS1000 is receiving a signal that is close to,
but outside the industry tolerances for that sample rate. The unit will operate
correctly, but with the filterbank frequencies scaled by a corresponding amount.
■Input LEDs
If the AES LED is lit, the DNS1000 is receiving data through its AES/EBU input. If the
SPDIF LED is lit, the unit is receiving data through its SPDIF input. If data is
presented to both inputs simultaneously, the input that was first locked to audio
will retain priority.
If both LEDs are flashing alternately, the DNS1000 is unable to detect a valid signal
and can not lock to either input.
PAGE 4

PAGE 5
FRONT-PANEL INDICATORS AND CONTROLS
■Channel Selector
You can use the DNS1000 to process channel 1, channel 2, or both channels
presented to the active input.
■Range Selector
The Range Selector concentrates the unit’s activity into the desired part of
the audio spectrum.
■Level control
The Level control tells the DNS1000 how much noise is present in the input.
■Band Gain controls
The Band Gain controls determine the maximum amount of processing that
the DNS1000 will apply in each band.
■Activity LEDs
These offer a visual indication of the activity in each of the Bands.
■Bypass
This control allows you to monitor the processed or unprocessed signals.

PAGE 6

PAGE 7
OPERATING THE DNS1000
Introduction
The DNS1000 divides a signal into a large number of well defined bands.
Sophisticated digital filters analyse each of these bands and suppress the noise
independently in each. The innovative design of this filter bank allows you to
control the DNS1000 using relatively few front panel controls.
Bypass
You can route the input directly to the output by pressing the Bypass button. This
allows you to audition the signal before and after processing. The signal latency
is not affected by the Bypass state.
Channel Selector
Your first job will be to identify the channel(s) that include(s) the unwanted noise.
Press the CHAN 1 button if you wish to process channel 1 only. Press the CHAN 2
button if you wish to process channel 2 only. Press the STEREO button if you wish
to process both channels.
In Stereo mode, the DNS1000 processes both channels equally according to
the positions of the front panel controls.
Range Selector
Next, you should identify the frequency range or ranges in which the noise lies.
You can press each of the Range Selector buttons individually, or combine them
to choose any one of six possible processing ranges:
Low 20Hz to 400Hz
Mid 200Hz to 6kHz
High 4kHz to 18kHz (to 12kHz at 32kHz sample rate)
Low + Mid 20Hz to 6kHz
Mid + High 200Hz to 18kHz (to 12kHz at 32kHz sample rate)
Full Range 20Hz to 18kHz (to 12kHz at 32kHz sample rate)
To select Low + Mid or Mid + High, press the appropriate two buttons
simultaneously, or in quick succession while the first is flashing. To select Full
Range, press the Low and High buttons simultaneously or in quick succession.
Selecting a range concentrates all of the filters within the DNS1000’s filter
bank across that part of the audio spectrum.

Level control
Your next job will be to identify the noise level of the audio.
With the appropriate channel(s) and range(s) selected, pull all six Band Gain
controls and the Level control down fully. Now increase the Level slowly. At first,
you will hear very little happen but, at some point determined by the noise
content of the recording, you will hear the noise disappear. You should attempt to
find the point at which this occurs.
When you place the Band Gain controls in this position, maximum
processing will occur as you increase the Level control, thus making
identification of the noise easier.
Band Gain controls
Once you have chosen the range(s) and determined the Level, you control the
action of the DNS1000’s filter bank using the Band Gain controls.
The six faders represent six frequency bands distributed from lower frequencies
(left) to higher frequencies (right) across the selected range.
You will use the Band Gain controls to control the amount of noise attenuation
performed in each band, adjusting them to suppress as much noise as possible
without introducing unwanted artefacts into the desired signal.
Noise suppression occurs in a given band when the fader is below the 0dB line.
However, there are occasions when you might wish to boost the signal in a given
band, and you can do this by moving the appropriate fader above the 0dB line.
Activity LEDs
The twelve Activity LEDs offer a visual indication of the activity in each of the six
bands controlled by the Band Gain controls.
Both LEDs off: Less than ±0.5dB activity
Green LED dim: Between 0.5dB and 3dB attenuation
Green LED bright: Greater than 3dB attenuation
Red LED dim: Between 0.5dB and 3dB boost
Red LED bright: Greater than 3dB boost
Note that each band controls numerous filters. Therefore, the Activity LEDsin a
given band display the overall activity in that band, and are not necessarily
indicative of the action of any single filter at that moment.
PAGE 8

PAGE 9
CASE STUDIES
The following case studies describe just three of the ways in which you can use
the DNS1000. You can apply the DNS1000 equally to recorded signals and to ‘live’
signals at the point of recording or transmission.
1. Suppressing traffic noise and other ambient sound
The DNS1000 can suppress background noises such as road traffic, aircraft, air
conditioning, wind, rain, and many other common soundstage, location, and OB
problems that contaminate audio. If your signal exhibits any of these problems,
you can suppress them as follows.
First, identify the frequency range(s) in which the noise lies.
You should be able to do this by listening to the problem. However, if this proves
difficult, you can use the following method.
It is not important that you find the perfect settings at the first attempt. In
particular, you will be able to refine your Level and Band Gain settings once
you have found the correct range.
Begin as follows:
Select the correct channel(s)
Ensure that the DNS1000 is not in Bypass
Select Full Range
•Set all six Band Gain controls to -24dB
•Raise the Level control until the noise disappears
At this point you have determined an approximate setting for the Level. This is
necessary for determining the range but it is likely that you will refine this later in
the procedure.
When the Level is close to the ideal setting, you should see the Activity
LEDs flicker in response to the signal content.
Now continue as follows:
•Raise the Band Gain controls to 0dB (no processing occurs)
•Adjust the Band Gain controls to suppress the noise
You should always attempt to suppress the noise with the minimum of
damage to the desired signal.
In all likelihood, you will find that the leftmost Band Gain controls are pulled down
significantly, whereas the central and rightmost are close to 0dB. This tells you
that the problem does not lie in the upper frequencies, so you should use the
Range Selector to select Low+Mid. Then repeat the steps marked “•”.

If you now find that you are using all six faders in similar fashion, it is likely
that the noise is distributed across the entire Low+Mid range. However, if the
suppression is still heavily biased towards the left hand faders, you should
now select the Low range alone and repeat the procedure.
If you select Low alone and cannot suppress the noise, it is probable
that there is considerable noise energy in the Mid band, so you should
return to using Low+Mid ranges.
For many problems such as traffic noise, the noise will lie primarily in the range
50Hz - 1.5kHz. In this case, Low+Mid will be the correct choice.
Second, optimise the Level control.
Listening carefully to the audio, refine the Level setting so that the noise is
correctly identified without introducing audible artefacts. If this proves difficult,
you can return the Band Gain controls to -24dB for this stage.
The DNS1000 takes a short period to “settle” after moving the Level control
(especially in the lower ranges) so you should not adjust it rapidly.
Third, refine the Band Gain controls for optimum suppression.
Set all six Band Gain controls to 0dB. Now increase and decrease the Gain in
each band separately while listening to the effect that each has on the noise. This
will identify the bands that contain the majority of the noise. (Do not be alarmed if
all six bands contain significant noise. This is not unusual.)
Let’s assume that the
greatest improvement
occurs when you reduce
the Gain in bands 3 and 4.
This suggests that the
noise is concentrated in an
approximate range of
200Hz to 1kHz. You should
now find the optimum
positions for all six faders.
The greatest cuts will lie in
bands 3 and 4, whereas
bands 1, 2, 5 and 6 should
remain as close to 0dB as
possible to ensure that
minimal signal damage
occurs in the bands that
do not contain much
noise.
The final configuration may
look like this:
PAGE 10

PAGE 11
2. Suppressing tape hiss
The DNS1000 can suppress the tape hiss that mars many older recordings. It will
also improve the signal/noise ratio of dialogue tapes that have been poorly
copied as well as those that are many generations old.
First, identify the frequency range(s) in which the noise lies.
You should follow the procedure laid down in case 1 to determine the range(s) in
which the problem lies. For most instances of tape hiss, you will find that the
Mid+High ranges are most appropriate. In a few cases you may find that the High
range alone is most suitable.
It is not as common to require suppression in the Low range because hiss
is usually less prominent at lower frequencies, and it may also be masked
by the genuine audio in the range.
Second, optimise the Level control.
To determine the correct Level, you should again follow the procedure described
in case 1.
Third, refine the Band Gain controls for optimum suppression.
As in case 1, you should start with all six Band Gain controls at 0dB. You should
then increase and decrease each control individually to find the bands that
contribute most hiss to the signal. Because tape hiss often exhibits a “white”
profile at Mid and High frequencies, you may find that satisfactory results are
achieved with the Band
Gain controls set in a
horizontal line.
However, hiss is generally
less annoying at very high
audio frequencies.
Consequently, you may be
able to reduce the amount
of processing in the
uppermost bands. This will
help to ensure that any low
amplitude signal
components lying at high
frequencies (which provide
much of the “air”,
“ambience” or “life” in a
signal) are passed with
little or no attenuation.
The final configuration may
look like this:

3. Suppressing excessive reverberation
In many situations, the DNS1000 can suppress excessive reverberation. This can
be useful in TV production when you need to match the audio from a large
recording studio or soundstage to visual images set in a small room or other
enclosed space. Suppressing reverberation can also be beneficial in increasing
the intelligibility of poor dialogue recordings.
The method used to suppress reverberation is quite different from that applied in
cases 1 and 2, and is as follows:
First, set the range in which the reverberation lies.
In general, reverberant spaces include soft materials that absorb high
frequencies more rapidly than middle and lower frequencies. Even bare rooms
with hard walls include these materials: they are the actors.
Consequently, you will find that Low+Mid is almost always the most appropriate
combination of ranges for suppressing reverberation.
Second, set the Band Gain controls.
You should set all six Band Gain controls to -24dB. This will ensure that (provided
the other controls are set correctly) the DNS1000 processes the “tails” of the sound
without adversely affecting the desired signal.
Third, optimise the Level control.
Starting at its minimum
position (-80dB) increase
the Level control slowly. At
some point before full
noise suppression
becomes apparent, you
will hear the tails of louder
sounds become truncated.
You can adjust the amount
of truncation of the reverb
using the Level control
rather than the Band Gain
controls.
The final configuration may
look like this:
PAGE 12

PAGE 13
SPECIFICATIONS
General
Power supply: 85–260VAC; 50–60Hz Power consumption: 20W
Overall dimensions: 70 x 230 x 285 mm Weight: 2.1kg (net); 3kg (gross)
Audio
I/O type: Digital PCM Sample rates: 32, 44.1, 48 kHz
I/O resolution: 24 bits Varispeed: approx. ±4%
Data formats: SPDIF or AES/EBU Processor power: 120 Mflops
Latency: <10 samples Process resolution: 40 bits
EMC REGULATIONS
In order to comply with EMC regulations, you must connect the DNS1000 using
metal-shelled connectors and good quality shielded cable suitable for digital
audio.
Declaration of conformity
Date of issue 1 October 2000
Equipment CEDAR DNS1000
Manufacturer CEDAR Audio Ltd
Address 20 Home End, Fulbourn, Cambridge CB1 5BS, UK
This is to certify that the aforementioned equipment, when used in accordance
with the instructions in this manual, fully conforms to the protection requirements
of the following EC Council Directives: on the approximation of the laws of the
member states relating to:
■89/336/EEC Electromagnetic Compatibility
Applicable standards: EN 55103-1:1996
EN 55103-2:1996
■73/23/EEC Low Voltage Equipment
Applicable standard: EN 60065:1998
E&OE.
The Company reserves the right to change specifications without notice.

LICENCE AND LIMITED WARRANTY
1. DEFINITIONS
In this Licence and Limited Warranty the following words and phrases shall bear the following meanings:
‘the Company’ is CEDAR Audio Limited of 20 Home End, Fulbourn, Cambridge CB1 5BS, UK;
‘the System’ means an instance of the sound-reprocessing system comprising hardware and
software held on EPROM (‘firmware’) developed by the Company;
‘this Document’ means this Licence and Limited Warranty.
2. ISSUE AND USE OF THE SYSTEM
2.1 The terms and conditions of this Document are implicitly accepted by any person or body
corporate who shall at any time use or have access to the System, and are effective from the
date of supply of the System by CEDAR Audio Limited to its immediate customer.
2.2 The Company hereby grants to the Licensee and the Licensee agrees to accept a
non-exclusive right to use the System.
3. PROPERTY AND CONFIDENTIALITY
3.1 The System contains confidential information of the Company and all copyright, trade marks,
trade names, styles and logos and other intellectual property rights in the System including
all documentation and manuals relating thereto are the exclusive property of the Company.
The Licensee acknowledges that all such rights are the property of the Company and shall
not question or dispute the ownership of any such rights nor use or adopt any trading name
or style similar to that of the Company.
3.2 The Licensee shall not attempt to reverse engineer, modify, copy, merge or transcribe the
whole or any part of the System or any information or documentation relating thereto.
3.3 The Licensee shall take all reasonable steps to protect the confidential information and
intellectual property rights of the Company.
4. LIMITED WARRANTY AND POST-WARRANTY OBLIGATIONS
4.1 The Company warrants that the System will perform substantially in accordance with the
appropriate section of its accompanying product manual for a period of one year from the
date of supply to the Company’s immediate customers.
4.2 The Company will make good at its own expenses by repair or replacement any defect or failure
that develops in the System within one year of supply to the Company’s immediate customer.
4.3 The Company shall have no liability to remedy any defect, failure, error or malfunction that
arises as a result of any improper use, operation or neglect of the System, or any attempt to
repair or modify the System by any person other than the Company or a person appointed
with the Company’s prior written consent.
4.4 In the case of any defect or failure in the System occurring more than twelve months after its
supply to the Company’s immediate customer the Company will at its option and for a
reasonable fee make good such defect or failure by repair or replacement (at the option of
the Company) subject to the faulty equipment having first been returned to the Company.
The Company will use reasonable efforts to return repaired or replacement items promptly, all
shipping, handling and insurance costs being for the account of the Licensee.
4.5 The above undertakings 4.1 to 4.4 are accepted by the Licensee in lieu of any other legal
remedy in respect of any defect or failure occurring during the said period and of any other
obligations or warranties expressed or implied including but not limited to the implied
warranties of saleability and fitness for a specific purpose.
4.6 The Licensee hereby acknowledges and accepts that nothing in this Document shall impose
upon the Company any obligation to repair or replace any item after a time when it is no
longer produced or offered for supply by the Company or which the Company certifies has
been superseded by a later version or has become obsolete.
5. FORCE MAJEURE
The Company shall not be liable for any breach of its obligations hereunder resulting from causes
beyond its reasonable control including, but not limited to, fires, strikes (of its own or other employees),

insurrection or riots, embargoes, container shortages, wrecks or delays in transportation, inability to
obtain supplies and raw materials, or requirements or regulations of any civil or military authority.
6. WAIVER
The waiver by either party of a breach of the provisions hereof by the other shall not be construed
as a waiver of any succeeding breach of the same or other provisions, nor shall any delay or
omission on the part of either party to exercise any right that it may have under this Licence
operate as a waiver of any breach or default by the other party.
7. NOTICES
Any notices or instruction to be given hereunder shall be delivered or sent by first-class post or
telecopier to the other party, and shall be deemed to have been served (if delivered) at the time of
delivery or (if sent by post) upon the expiration of seven days after posting or (if sent by telecopier)
upon the expiration of twelve hours after transmission.
8. ASSIGNMENT AND SUB-LICENSING
The Licensee may at his discretion assign the System and in doing so shall assign this Licence its
rights and obligations to the purchaser who shall without reservation agree to be bound by this
Licence. The original Licensee and any subsequent Licensees shall be bound by the obligations of
this Licence in perpetuity.
9. LIMITATION OF LIABILITY
The Company’s maximum liability under any claim including any claim in respect of infringement of
the intellectual property rights of any third party shall be, at the option of the Company either:
(a) return of a sum calculated as the price received for the System by the Company from its
immediate customer depreciated on a straight line basis over a one year write-off period; or
(b) repair or replacement of those components of the System that do not meet the warranties
contained within this Document.
The foregoing states the entire liability of the Company to the Licensee.
10. CONSEQUENTIAL LOSS
Even if the Company has been advised of the possibility of such damages, and notwithstanding
anything else contained herein the Company shall under no event be liable to the Licensee or to any
other persons for loss of profits or contracts or damage (whether direct or consequential) arising in
connection with the System or any modification, variation or enhancement thereof and including any
documentation or data provided by the Company or for any other indirect or consequential loss.
11. ENTIRE AGREEMENT
The Company shall not be liable to the Licensee for any loss arising in connection with any
representations, agreements, statements or undertakings made prior to the date of supply of the
System to the Licensee.
12. TERMINATION
This Licence may be terminated forthwith by the Company if the Licensee commits any material
breach of any terms of this Licence. Forthwith upon such termination the Company shall have
immediate right of access to the System for the purpose of removing it.
13. SEVERABILITY
Notwithstanding that the whole or any part of any provision of this Document may prove to be
illegal or unenforceable the other provisions of this Document and the remainder of the provision in
question shall remain in full force and effect.
14. HEADINGS
The headings to the Clauses are for ease of reference only and shall not affect the interpretation or
construction of this Document.
15. LAW
This Document shall be governed by and construed in accordance with English law and all
disputes between the parties which cannot be resolved by negotiation shall be determined by
arbitration in England in accordance with the Arbitration Act 1950 and 1979.

CEDAR DNS1000
Designed and manufactured by
CEDAR Audio Ltd
20 Home End
Fulbourn
Cambridge CB1 5BS
United Kingdom
www.cedaraudio.com
[email protected]
Serial number:
Inspected:
QC Engineer: