Cedar Duo Series User manual

The Duo Series
declickle and auto dehiss
Version 1.2
19 September 2004
Copyright CEDAR Audio Ltd, © 2004
CEDAR is a registered trademark of CEDAR Audio Ltd
Duo, declickle and auto dehiss are trademarks of CEDAR Audio Ltd
E&OE, Subject to revision at the Company’s sole discretion
interstage
Phistersvej 31, 2900 Hellerup, Danmark
Telefon [phone], fax [phone]
www.interstage.dk
-pro audio with a smile

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Table Of Contents
i
Table Of Contents
Introducing the CEDAR Duos ........................................................................................... 1
Specifications and CE Certificates..................................................................................... 2
Contact Information....................................................................................................... 4
Technical Support.......................................................................................................... 5
Safety Instructions ........................................................................................................ 6
Getting Started ............................................................................................................. 7
Front Panel Indicators and Controls .................................................................................. 8
General Set-up and Connections ...................................................................................... 9
Memories ................................................................................................................... 14
Remote Control (MIDI) Implementation .......................................................................... 16
Declickle: Removing impulsive noises ............................................................................. 18
Declickle tutorial ......................................................................................................... 20
An Introduction to Click and Crackle Removal .................................................................. 21
Auto dehiss: Reducing broadband noise .......................................................................... 26
Auto dehiss tutorials .................................................................................................... 30
A Short History of Noise Reduction ................................................................................. 34
Licence and Limited Warranty........................................................................................ 37

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CEDAR Duo
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Introducing the CEDAR Duos
CEDAR Duo declickle module
CEDAR Duo auto dehiss module
Thank you for purchasing this CEDAR Duo audio restoration module. It is one of a family of the
world’s most advanced and most effective noise removal units, and it offers outstanding
processing power and performance. Quality, speed and simplicity are paramount considerations
in the Duo design, and both units are intended for professional use. Features include the
following:
■Flexibility
Both Duo models handle a wide range of audio restoration requirements.
■Portability
Each Duo is a compact, lightweight unit designed to fit a standard 1U rack space.
■Audio interfaces
Duos incorporate 96kHz, 24-bit digital audio interfaces conforming to the AES/EBU and SPDIF
standards.
■Power
Their universal power supplies means that Duos work anywhere in the world.
■Processor
Two, powerful SHARC processors ensure that a Duo will handle the most complex processing
requirements.

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Specifications and CE Certificates
General:
Power supply: 85–260VAC; 50–60Hz
I/O type: Digital PCM
Power consumption: 15W (standby 1W)
I/O resolution: 24 bits
Overall dimensions: 45 x 483 x 240mm
Sample rate: 30–100kHz
Weight: 3kg (net); 4kg (gross)
Data format: SPDIF or AES/EBU
Processor: 400 Mflops (peak)
Group delay (milliseconds):
declickle
(processing)
auto dehiss
(processing)
44.1kHz
190ms
463ms
48kHz
174ms
458ms
88.2kHz
95ms
461ms
96kHz
87ms
456ms
In Bypass, each unit has a latency of less than five samples, irrespective of sample rate.
EMC Regulations:
In order to comply fully with EMC regulations, a Duo should be connected using metal-shelled
connectors and good quality shielded cable suitable for digital audio.

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Declaration of conformity:
Date of issue: 1 April 2004
Equipment: CEDAR Duo
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:
n89/336/EEC Electromagnetic Compatibility
Applicable standards: EN 50081-1:92
EN 50082-1:92
n73/23/EEC Low Voltage Equipment
Applicable standard: BSEN 60-065:1994

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Contact Information
Headquarters:
Address:
CEDAR Audio Limited, 20 Home End, Fulbourn, Cambridge, CB1 5BS,
United Kingdom
Telephone and Fax:
T: [phone] F: [phone]
Email:
[e-mail]
USA Office:
Address:
CEDAR Audio USA, 43 Deerfield Road, Portland, ME 04101-1805, USA
Telephone and Fax:
T: [phone] F: [phone]
Email:
[e-mail]
Asian Office:
Address:
CEDAR Asia (Mailing address)
Attention: David William Robinson, Tanglin Post Office, PO Box 282,
Singapore 912410
Telephone and Fax:
T: [phone] F: [phone]
Email:
[e-mail]
Web:
Web:
www.cedaraudio.com
Worldwide Dealer List:
For an up-to-date dealer list, please visit www.cedaraudio.com

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Technical Support
We hope that you will never need to read this page, but should you experience difficulties with
your CEDAR Duo, please contact your local dealer or CEDAR office. Alternatively, you may send
an email to [e-mail]. In either case, please provide the following details:
■Your Duo hardware and software version numbers. (See General Set-up and Connections)
■A precise description of the problem
■All details shown in the status page.
Thank you.

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Safety Instructions
Read these instructions, follow them, and save them for future
reference.
■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 a Duo to reach ambient temperatures naturally before
connecting the mains power.
■Mounting and ventilation
The unit may be mounted in a 19" EIA rack, or placed on a flat, stable surface. Do not subject it
to strong sunlight, excessive dust, mechanical vibration or periodic shocks. A Duo is not
susceptible to heat build-up, but should be installed away from heat sources such as radiators,
and audio devices such as amplifiers that produce large amounts of heat. If it is used as a free-
standing unit, the supplied rubber feet should be fixed to the base of the unit.
■Power sources
Each Duo features a universal power supply that will work safely on any mains supply in the
ranges 85V to 260V, 50Hz or 60Hz AC only. The unit should always be grounded (or ‘earthed’),
and power connectors should be routed so that they will not be walked on or pinched.
A Duo is connected to the mains power as long as it is plugged in to a mains supply, so if it is
not to be used for an extended period, unplug it from the wall. Pull the connector out by the
plug, never by the cord itself.
■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
A Duo 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.

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Getting Started
Unpacking
Unpack the Duo carefully. Save the carton and all packing materials since you may need them
to transport the unit in the future. In addition to the Duo and the packaging, the carton should
contain the following:
■mains connection lead
■this manual
■rack mounting hardware
■four self-adhesive feet
Installation site
To maintain reliability and prolong operating life, observe the following environmental
considerations:
■the nominal temperature should be maintained between 5° and 35° Celsius
■relative humidity should be in the range 30% to 80% non-condensing
■strong magnetic fields should not exist nearby.

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Front Panel Indicators and Controls
Power switch and power LEDs
■When OFF, the Duo is in standby mode.
■When ON, the Duo is powered up and operational.
The power status is reported by the power LEDs on the right of the front panel.
Warning: The unit is not powered off completely unless the power lead is removed.
Screen, soft buttons and spin wheel
The set up and operation of the Duo is determined using the illuminated 'soft' buttons and the
spin wheel.
■When a control or menu option is available, the button alongside it will be faintly illuminated.
■When an option is selected for adjustment, the button alongside it will be fully illuminated.
Adjustment is carried out either by (i) repeated pressing of the illuminated button, or (ii)
rotating the spinwheel in either direction, as appropriate.
■If no menu or control is associated with a button, it is not illuminated.

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General Set-up and Connections
Basic Set-up
When you switch on the Duo, it will present one of the following screens to you. These are the
Main screens for declickle and auto dehiss, respectively. To set up the unit and access a number
of less often required parameters, press the MENU option.
declickle main screen
auto dehiss main screen (auto mode)
auto dehiss main screen (manual mode)
Menu
You will now be presented with the MENU screen:
declickle menu screen
auto dehiss menu screen

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These offer five or six options, depending upon the product. Press the desired option to access
the screen of your choice.
■SETUP: Enter the set-up and reset screen
■AUDIO I/O: Enter the audio set-up and monitoring screen
■PROCESS MODE: Enter the AUTO DEHISS process mode screen.
■MEMORY: Enter the memory screens to name, save, recall and delete user memories
■CLOSE: Returns you to the main operation screen
■STATUS: Provides information about the operation of the unit
Setup
■Contrast
Press the CONTRAST option and use the spinwheel to alter the contrast of the display to suit
your viewing angle.
■MIDI Channel
Press the MIDI CH option and use the spinwheel to select the desired MIDI channel for remote
control.
■Reset
Press RESET to reset the Duo to the factory defaults. This will clear all user-defined parameters
and all the memories. You will be asked to CANCEL or CONFIRM the RESET.
Pressing CANCEL will return you to the Setup screen.
Pressing CONFIRM will reset the unit to the factory defaults and return you to the Main screen.
■Close
Press CLOSE to return to the Main screen.
■Version number
Reports the version number of the software installed in this Duo.

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■Serial number
Reports the serial number of this unit.
Audio I/O
■Output
Press the OUTPUT option repeatedly to cycle through 16, 18, 20 and 24-bit output wordlength
options. You should choose the option most suitable for the next device in the audio chain.
The internal 32-bit wordlengths are dithered to the output wordlength using TPDF dithering.
■Gain
Press the GAIN option and use the spinwheel to adjust the gain of the unit between -10dB and
+10dB in steps of 0.1dB.
■Level
This displays the signal level presented to the unit's input. A 'peak hold' is implemented, and the
unit will display the word CLIP! if it detects digital ‘overs’.
Pressing the LEVEL button in this screen will reset the peak hold.
■Bypass
Press the BYPASS option to bypass the Duo's processing. In this mode, the Duo is 24-bit
transparent. The latency is reduced to less than 10 samples.
■Close
Press CLOSE to return to the Main screen.
Physical Connections
Audio
Your Duo offers two audio connection standards, and passes its signal to both outputs
irrespective of the input used. The standards are:
■Digital SPDIF format audio data
SPDIF is used by domestic and semi-professional digital audio devices.
You should connect the SPDIF output from your source to the SPDIF input of the Duo using a
single cable terminated with an RCA (or 'phono') plug. The SPDIF output of the Duo should be
connected to the SPDIF input of a recording device or external DAC.

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■Digital AES/EBU format audio data
The AES/EBU format is used by professional digital audio devices. You should connect the
AES/EBU output from your source to the AES/EBU input of the Duo using a single cable
terminated with an XLR plug. The AES/EBU output of the Duo should be connected to the
AES/EBU input of a recording device or external DAC.
No Duo processes are affected by channel status data. All units will echo any such data directly
to the outputs.
Input Selection
The Duo will automatically switch to whichever input is receiving a valid signal. If both inputs
are active when you switch on, the Duo may not select the input you require, so it is advisable
only to present signal to one input at a time.
MIDI
The Duo offers MIDI In, Out and Thru. These operate in the conventional manner.
Use MIDI to store and recall the memories, and to control the Duo using external equipment.
See MEMORIES.
USB
The Duo offers a USB socket. This is for factory use only.
Status
The Menu/Status page provides important information about the operation of your unit, and
technical support information in the event of a failure.
Status
■Input
There are three options:
■LOCK XLR: A valid digital signal is being received at the XLR (AES/EBU) input and the Duo has
locked to this
■LOCK RCA: A valid digital signal is being received at the RCA/phono (SPDIF) input and the
Duo has locked to this

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■OFF LOCK: No valid digital signal is being received at either the AES/EBU input or the
RCA/phono (SPDIF) input and the Duo is not locked to incoming audio
■FS (Sample rate)
This shows the measured sample rate of incoming audio, and is accurate to approximately
0.01%.
This field is blank if the Duo is OFF LOCK
■DSPn: NN NN mm
This provides information about each of the SHARC processors within the Duo.
■NN NN: These are status codes that should be reported to CEDAR Audio in the event of a
failure
■mm: This field reports two messages, "OK" or "ERROR"
■Close
Press CLOSE to return to the Main screen.

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Memories
Your Duo offers 99 memory locations in addition to the current workspace. The workspace is
volatile, so it is useful to be able to store and recall set-ups. You do so using the MEMORY
screens, as follows.
Press the MEMORY option in the MENU screen to access the memory screens. When you press
this for the first time, the following screen will appear:
There are six options:
Mem:xx
The number XX shown here tells you which memory location is being addressed. To change
memory location, press the soft button associated with this option and use the spinwheel to
select other memories.
Store
Press this to save the current workspace in the location MEM:XX shown above.
Recall
Press this to load the settings in MEM:XX into the current workspace.
Rename
When you press RENAME, the following screen will appear:
■CLEAR: Press this to clear the current name
■NEXT: Moves the edit cursor to the right
■DELETE: Deletes the current character (identified by an underline) and moves the edit cursor
to the left

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■CANCEL: Exits from this screen without making any changes, and returns you to the MEMORY
screen
■DONE: Saves the name changes, exits from this screen, and returns you to the MEMORY
screen
You may change the identified character by rotating the spinwheel clockwise or anticlockwise, as
appropriate.
If you do not choose a name for a memory, it will be set to MEMORYXX by default:
If you clear a name and do not replace it, the Duo will insert UN-NAMED as the default.
Close
Closes this screen and returns you to the Main screen.
Delete
Deletes the contents of the current memory, MEM:XX. Use this with care; you will not be
prompted to confirm the operation.
When the Duo is first switched on, it recalls the settings held in MEM:01. If you wish to create a
default set-up, store it here.

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Remote Control (MIDI) Implementation
Standard MIDI control messages may be used to control all the Duos' audio parameters. The
only system parameters that can be altered from the front panel but which cannot be edited via
MIDI are the display contrast and the MIDI channel.
■Audio parameters are adjusted by sending MIDI controller change messages.
■User memories may be stored and recalled using MIDI patch change messages.
MIDI Controller Numbers (All models)
Command
CC#
Comments
Bypass
16
■0-63 = Bypass OFF
■64-127 = Bypass ON
Makeup Gain
17
0-127 maps to -10dB to +10dB
Wordlength
18
■0-31 = 16-bit
■32-63 = 18-bit
■64-95 = 20-bit
■96-127 = 24-bit
On/Off
19
■0-63 = Processing OFF
■64-127 = Processing ON
MIDI Controller Numbers (Declickle only)
Command
CC#
Comments
Threshold
(left)
20
0-127 is scaled to 0-99
Threshold
(right)
21
0-127 is scaled to 0-99
Model (left)
22
0-127 is scaled to 0-99
Model (right)
23
0-127 is scaled to 0-99
Detect
24
■0-42 = fine
■43-84 = medium
■85-127 = coarse