Sonifex Redbox RB-AEC User manual

Manufacturers of audio & video
products for radio & TV broadcasters
Redbox RB-AEC
Acoustic Echo Canceller
HANDBOOK

RB-AEC Handbook
This handbook is for use with the following product:
Redbox RB-AEC Acoustic Echo Canceller
Stock Code: 30-285
Revision 1.04, June 2015
©Sonifex Ltd, 2015
All Rights Reserved
Sonifex Ltd, 61, Station Road, Irthlingborough,
Northants, NN9 5QE, England.
Tel: [phone]
Fax: [phone]
Email: [email protected]o.uk
Website: http://www.sonifex.co.uk
Information in this document is subject to change without notice and does not represent a
commitment on the part of the vendor. Sonifex Ltd shall not be liable for any loss or damage
whatsoever arising from the use of information or any error contained in this manual.
No part of this manual may be reproduced or transmitted in any form or by any means, electronic
or mechanical, including photocopying, recording, information storage and retrieval systems, for any
purpose other than the purchaser’s personal use, without the express written permission of Sonifex
Ltd. Unless otherwise noted, all names of companies, products and persons contained herein are part
of a completely fictitious adaptation and are designed solely to document the use of Sonifex product.
Made in the UK by

Contents & Figures
Contents
Product Warranty - 2 Year i
Sonifex Warranty & Liability Terms & Conditions i
1. Definitions i
2. Warranty i
Unpacking Your Product iii
Repairs & Returns iii
CE Declaration of Conformity and Approval Information iv
Safety & Installation of Mains Operated Equipment v
Voltage Setting Checks v
Fuse Rating v
Power Cable & Connection v
WEEE Directive vi
RoHS Directive vi
Atmosphere vi
Fitting Redboxes vi
Introduction 1
Category 1
Product Function 1
Typical Applications 1
Features 1
System Block Diagram 2
Operation of the RB-AEC 2
Front Panel Controls and Indicators 4
Power LED 4
Reset Button 4
Rear Panel Connections and Controls 4
Inputs 4
Outputs 4
Settings DIPSwitch 5
GPIO Connector 6
Ethernet Port 6
Mains Power 6
Applications 7
How to Remove Delayed Presenter’s Audio From Their
Earpiece 7
The Problem: 7
The Solution: 7
How to Remove Delayed Caller Audio From Telephone Line 8
The Problem: 8
The Solution: 8
Calibration 9
Webserver & Unit Discovery 10
Running The Webserver 10
Home Page 11
Far End and Near End Input Type 11
Adaption Status 11
Sample Rate 12
Offset 12
Reset Coefficients 12
Save Coefficients 12
Load Saved Coefficients Now 12
Load Saved Coefficients on Startup 12
Far End Silence Detect Threshold: 12
Enable Noise Gate: 12
Noise Gate Threshold: 13
Noise Gate Release Time: 13
Network Page 13
Network Settings 13
Host Name 13
Static IP Address 14
Static Subnet Mask 14
Gateway IP Address 14
Dynamic Addressing 14
Device Info Page 14
Update Page 15
Update 15
Technical Specification For RB-AEC 16
Figures
Fig 1-1: The RB-AEC Acoustic Echo Canceller 1
Fig 1-2: The RB-AEC Operational Block Diagram 2
Fig 1-3: The RB-AEC Functional Block Diagram 3
Fig 2-1: The RB-AEC Front Panel 4
Fig 2-2: The RB-AEC Rear Panel 5
Fig 4-1: The RB-AEC Sonifex Service Discovery Tool 10
Fig 4-2: The RB-AEC Webserver Interface - Home 11
Fig 4-3: The RB-AEC Webserver Interface - Configuration 12
Fig 4-4: The RB-AEC Webserver Interface - Network 13
Fig 4-5: The RB-AEC Webserver Interface - Device Info 14
Fig 4-6: The RB-AEC Webserver Interface - Update 15

Warranty Registration
Sonifex Limited y61 Station Road yIrthlingborough yNorthamptonshire yNN9 5QE yUnited Kingdom
Tel: [phone] yFax: [phone] yEmail: [email protected] yInternet: www.sonifex.co.uk
As standard, Sonifex products are supplied with a 1 year back to base
warranty.
If you register the product online, you can increase your product warranty to
2 years and we can also keep you informed of any product design
improvements or modifications.
To register your product, please go online to www.sonifex.co.uk/register
Register Online for an
Extended 2 Year Warranty

i
Warranty
Product Warranty - 2 Year
As standard, Sonifex products are supplied with a 1 year back to base
warranty. In order to register the date of purchase and so that we can keep
you informed of any product design improvements or modifications, it is
important to complete the warranty registration online. Additionally, if you
register the product on the Sonifex website within 30 days of purchase, you
can increase your product warranty to 2 years. Go to the Sonifex website at:
http://www.sonifex.co.uk/technical/register/index.asp to apply for your 2
year warranty.
Note: For your own records the product serial number is recorded on the
CE certification page of this handbook.
Sonifex Warranty & Liability Terms & Conditions
1. Definitions
‘the Company’ means Sonifex Ltd and where relevant includes companies
within the same group of companies as Sonifex Limited.
‘the Goods’ means the goods or any part thereof supplied by the Company
and where relevant includes: work carried out by the Company on items
supplied by the Purchaser; services supplied by the Company; and software
supplied by the Company.
‘the Purchaser’ means the person or organisation who buys or has agreed
to buy the Goods.
‘the Price’ means the Price of the Goods and any other charges incurred by
the Company in the supply of the Goods.
‘the Warranty Term’ is the length of the product warranty which is usually
12 months from the date of despatch; except when the product has been
registered at the Sonifex website when the Warranty Term is 24 months
from the date of despatch.
‘the Contract’ means the quotation, these Conditions of Sale and any
other document incorporated in a contract between the Company and the
Purchaser.
This is the entire Contract between the parties relating to the subject
matter hereof and may not be changed or terminated except in writing in
accordance with the provisions of this Contract. A reference to the consent,
acknowledgement, authority or agreement of the Company means in
writing and only by a director of the Company.
2. Warranty
(a) The Company agrees to repair or (at its discretion) replace Goods
which are found to be defective (fair wear and tear excepted) and
which are returned to the Company within the Warranty Term
provided that each of the following are satisfied:
(i) notification of any defect is given to the Company immediately
upon its becoming apparent to the Purchaser;
(ii) the Goods have only been operated under normal operating
conditions and have only been subject to normal use (and
in particular the Goods must have been correctly connected
and must not have been subject to high voltage or to ionising
radiation and must not have been used contrary to the
Company’s technical recommendations);
(iii) the Goods are returned to the Company’s premises at the
Purchaser’s expense;
(iv) any Goods or parts of Goods replaced shall become the
property of the Company;
(v) no work whatsoever (other than normal and proper
maintenance) has been carried out to the Goods or any part of
the Goods without the Company’s prior written consent;

ii
Warranty
(vi) the defect has not arisen from a design made, furnished or
specified by the Purchaser;
(vii) the Goods have been assembled or incorporated into other
goods only in accordance with any instructions issued by the
Company;
(viii) the defect has not arisen from a design modified by the
Purchaser;
(ix) the defect has not arisen from an item manufactured by
a person other than the Company. In respect of any item
manufactured by a person other than the Company, the
Purchaser shall only be entitled to the benefit of any warranty or
guarantee provided by such manufacturer to the Company.
(b) In respect of computer software supplied by the Company the
Company does not warrant that the use of the software will be
uninterrupted or error free.
(c) The Company accepts liability:
(i) for death or personal injury to the extent that it results from the
negligence of the Company, its employees (whilst in the course
of their employment) or its agents (in the course of the agency);
(ii) for any breach by the Company of any statutory undertaking as
to title, quiet possession and freedom from encumbrance.
(d) Subject to conditions (a) and (c) from the time of despatch of
the Goods from the Company’s premises the Purchaser shall be
responsible for any defect in the Goods or loss, damage, nuisance
or interference whatsoever consequential economic or otherwise or
wastage of material resulting from or caused by or to the Goods. In
particular the Company shall not be liable for any loss of profits or
other economic losses. The Company accordingly excludes all liability
for the same.
(e) At the request and expense of the Purchaser the Company will test
the Goods to ascertain performance levels and provide a report of
the results of that test. The report will be accurate at the time of the
test, to the best of the belief and knowledge of the Company, and the
Company accepts no liability in respect of its accuracy beyond that
set out in Condition (a).
(f) Subject to Condition (e) no representation, condition, warranty or
other term, express or implied (by statute or otherwise) is given by
the Company that the Goods are of any particular quality or standard
or will enable the Purchaser to attain any particular performance
or result, or will be suitable for any particular purpose or use
under specific conditions or will provide any particular capacity,
notwithstanding that the requirement for such performance, result or
capacity or that such particular purpose or conditions may have been
known (or ought to have been known) to the Company, its employees
or agents.
(g) (i) To the extent that the Company is held legally liable to the
Purchaser for any
single breach of contract, tort, representation or other act or
default, the Company’s liability for the same shall not exceed
the price of the Goods.
(ii) The restriction of liability in Condition (g)(i) shall not apply to
any liability accepted by the Seller in Condition (c).
(h) Where the Goods are sold under a consumer transaction (as defined
by the Consumer Transactions (Restrictions on Statements) Order
1976) the statutory rights of the Purchaser are not affected by these
Conditions of Sale.

iii
Repairs & Returns
Unpacking Your Product
Each product is shipped in protective packaging and should be inspected
for damage before use. If there is any transit damage take pictures of the
product packaging and notify the carrier immediately with all the relevant
details of the shipment. Packing materials should be kept for inspection and
also for if the product needs to be returned.
The product is shipped with the following equipment so please check to
ensure that you have all of the items below. If anything is missing, please
contact the supplier of your equipment immediately.
Item Quantity
Product Unit 1
IEC Mains lead fitted with moulded mains plug 1
Handbook and warranty card 1
If you require a different power lead, please let us know when ordering the
product.
Repairs & Returns
Please contact Sonifex or your supplier if you have any problems with your
Sonifex product. Email [e-mail] for the repair/
upgrade/returns procedure, or for support & questions regarding the
product operation.
പ

iv
CE Certification
61 Station Road • Irthlingborough • Northants
NN9 5QE • United Kingdom • www.sonifex.co.uk
T: [phone] • F: [phone]
Registered Office • 61 Station Road • Irthlingborough • Registered in England 1717864 • VAT Reg No. GB 119 85 32 52
CE Declaration of Conformity and
Approval Information
Product:
Serial No:
This document certifies that the Sonifex product that you have purchased is
compliant with CE specifications. If you would like further information on
compliance of all Sonifex products, please check the website at the address
above where full information is available.
Sonifex Limited hereby certify that the following product with serial
number shown has been designed and manufactured in accordance with
the following specifications :
EMC: EN 55103-1: 1997 Electromagnetic Compatibility.
Limits of disturbance for audio apparatus for professional use
For use in environments 1 to 4.
EN 55103-2: 1997 Electromagnetic Compatibility.
Limits of disturbance for audio apparatus for professional use
For use in environments 1 to 4.
Safety: EN 60950: 1992 Safety of Information Technology Equipment
Including Electrical Business Equipment.
Hybrid BS6301, BS7002, BS415, CTR21,
Approvals: R&TTE directive (1999/5/EC)
The Reference Technical Justification File for this product is available at
Sonifex Ltd.
Authorised By:
Name: Chris Stills
Position: Technical Director
Date of Issue: 01 June 2015
Signature:

v
Safety & Installation
Safety & Installation of Mains
Operated Equipment
There are no user serviceable parts inside the equipment. If you should
ever need to look inside the unit, always disconnect the mains supply
before removing the equipment covers. The cover is connected to earth
by means of the fixing screws. It is essential to maintain this earth/
ground connection to ensure a safe operating environment and provide
electromagnetic shielding.
Voltage Setting Checks
Ensure that the machine operating voltage is correct for your mains power
supply by checking the box in which your product was supplied. The voltage
is shown on the box label. The available voltage settings are 115V, or 230V.
Please note that all products are either switchable between 115V and 230V,
or have a universal power supply.
Fuse Rating
The product is supplied with a single fuse in the live conducting path of the
mains power input. For reasons of safety it is important that the correct
rating and type of fuse is used. Incorrectly rated fuses could present a
possible fire hazard, under equipment fault conditions. The active fuse is
fitted on the outside rear panel of the unit.
Power Cable & Connection
An IEC power connector is supplied with the product which has a moulded
plug attached – this is a legal requirement The mains lead is automatically
configured for the country that the product is being sent to, from one of :
Territory Voltage IEC Lead Type Image
UK & Middle East 230V UK 3 pin to IEC lead
Europe 230V European Schuko round 2 pin to
IEC lead
USA, Canada and
South America 115V 3 flat pin to IEC lead
Australia & New
Zealand 230V Australasian 3 flat pin to IEC lead
Connect the equipment in accordance with the connection details and
before applying power to the unit, check that the machine has the correct
operating voltage for your mains power supply.
Important Note: If there is an earth/ground terminal on the rear panel of
the product then it must be earthed/grounded.

vi
Safety & Installation
WEEE Directive
The Waste Electrical and Electronic Equipment (WEEE)
Directive was agreed on 13 February 2003, along with the
related Directive 2002/95/EC on Restrictions of the use of
certain Hazardous Substances in electrical and electronic
equipment (RoHS). The Waste Electrical and Electronic Equipment Directive
(WEEE) aims to minimise the impacts of electrical and electronic equipment
on the environment during their life times and when they become waste.
All products manufactured by Sonifex Ltd have the WEEE directive label
placed on the case. Sonifex Ltd will be happy to give you information about
local organisations that can reprocess the product when it reaches its “end
of use”, or alternatively all products that have reached “end of use” can be
returned to Sonifex and will be reprocessed correctly free of charge.
RoHS Directive
The RoHS directive limits the use of certain hazardous
substances currently used in EEE manufacture, including
lead, mercury, cadmium, hexavalent chromium, and
halide-containing compounds PBB (polybrominated biphenyl) and PBDE
(polybrominated diphenyl ether). Elimination of these substances will result
in more environmentally friendly recycling of electronic equipment.
Sonifex Ltd practices lead-free (LF) manufacturing processes and does not
use any of the hazardous substances identified in the European Union’s
Restriction of Hazardous Substances (RoHS) directive. The manufacturing
processes include the assembly of purchased components from various
sources. Product is offered as RoHS compliant, or LF, only after sufficient
evidence is received from the component manufacturers that their
components are RoHS compliant. Sonifex Ltd relies solely on the distributor,
or manufacturer, of the components for identification of RoHS compliance.
Thus whilst every effort is made to ensure compliance, Sonifex Ltd makes
no warranty, or certification, or declaration of compliance concerning said
components.
Atmosphere
The units should be installed in an area that is not subject to excessive
temperature variation (<0°C, >50°C), moisture, dust or vibration.
Fitting Redboxes
Redboxes can be fixed to the underside of a mixing desk, or other surfaces
using 4.2mm holes in the sides and fixed with 2 x M4 screws or 2 x No. 6
countersink wood screws.
They can also be rack-mounted, with either the front, or rear of the Redbox
positioned at the front of the rack:
Rear Mounting a 1U Rackmount Redbox:
The RB-RK3 1U rear panel rack kit can be used for large 1U rackmount
Redboxes.
Note: When fitting the RB-RK3 rear-mounting rack-kits, a notch has been left on the inside of the right-hand rack-piece for the mains cable to pass through.
Make sure that the mains cable has been put through the notch before attaching the right hand rack-piece.

1
Introduction 1
Introduction
Fig 1-1: The RB-AEC Acoustic Echo Canceller
Category
Synchronisers, Delays & Silence Detectors.
Product Function
Remove acoustic echo in a presenter’s earpiece caused by microphones
picking up audio from loudspeakers in delay.
Typical Applications
In a TV production environment where presenters are fed a signal which has
some form of acoustic delay or echo. Any situation where adaptive echo
cancellaton is required.
Features
The RB-AEC 1U rack-mount is an acoustic echo canceller primarily designed
for the benefit of studio personnel for television and radio. When a studio
presenter’s microphone signal is played out through a monitor speaker in
the control room, it can be picked up by the control room microphone(s)
and returned to the presenter’s earpiece as an undesirable echo.
In circumstances where green screen video processing is taking place, the
delay can be greater than 200ms. Additionally, the dimensions, occupancy
and distance between mouth and microphone can further influence the
echo. The RB-AEC is used to remove the entire control room monitor
speaker output from the presenter’s feed by adapting to the environment
in which the control room microphones are placed. Although acoustic echo
cancellation is more commonly implemented in telephony systems, the
Sonifex RB-AEC is designed to produce broadcast quality cancellation.
Much like during a conference call configuration between two rooms, each
room has a microphone and speaker to conduct a conversation. When an
occupant of one room speaks, it takes a certain length of time before it
is received in the second room. Without a suitable solution this ‘delayed’
signal can then be captured by the microphone in the second room and
returned back to the first room as an echo.
In the particular example of TV production, as well as the processing/
transmission delay, sound reflections from the control room monitor
speaker into the control room microphone(s) cause the studio earpiece to
suffer further delay. The sound reflections in the control room vary with
the contents of the room including any personnel present. Also, different
frequencies produce varying reflections across various types of surfaces
and magnitudes within the room. For a 15m distance between speaker and
microphone the delay is as much as 40ms.The DSP solution offered by the
RB-AEC can dynamically compensate for varying configurations.

2
1 Introduction
Operation of the RB-AEC
The post-processed transmission output program from the studio (A) is
sent to the RB-AEC as an analogue or digital audio signal (the stereo input
is auto-sensing) which acts as a mix-minus to the input signal (B) from
the Control Room. The RB-AEC removes the unwanted acoustic echoes so
that the audio sent to the presenter’s earpiece (C) is free of echoes and
reflection artifacts.
The RB-AEC is a high performance, reliable single channel acoustic echo
canceller designed to be a transparent addition to an exisiting studio
environment.
The canceller will auto-detect analogue and digital inputs with sample rates
up to 192kHz. Digital output is available when using a digital input and its
sample rate is set to the rate detected at the input.
The settings for the RB-AEC are adjusted using the onboard webserver
interface.
Studio
Before
Monitor/
Earpiece
Presenter
Receiving
Delayed
Audio
Mic
Approx 200ms
Delay
Vol
Control Room/
Gallery
Monitor
Speaker
Output
TB
Mic
Studio
After
Monitor/
Earpiece Mic
Approx 200ms
Delay
Vol
RB-AEC
(B)
(C)
Presenter Receiving
Artifact Free Audio
T(z) (A)
Control Room/
Gallery
Monitor
Speaker
Output
TB
Mic
System Block Diagram
Fig 1-2: The RB-AEC
Operational Block Diagram

3
Introduction 1
ANA/AES Input ANA Output
ANA Output
AES Output
ANA/AES Input
ADC DSP DAC
SRC
SRC
SRC
Fig 1-3: The RB-AEC Functional Block Diagram

4
2 Connections and Operation
Front Panel Controls and Indicators
Fig 2-1: The RB-AEC Front Panel
Power LED
The POWER LED illuminates whilst internal power is present within
the unit. If this indicator is not on, the most likely reason is simply the
absence of mains power, but under fault conditions it may also indicate
a ruptured mains fuse or a problem with the internal power supply
module.
Reset Button
In the unlikely event that the unit fails to respond, press and hold the
reset button for 3 seconds to reboot the unit
Rear Panel Connections and Controls
Inputs
Far End Input
An XLR 3 pin socket is used for the FAR END input channel and it can
take an analogue or AES/EBU digital feed. The input will automatically
detect whether the source is analogue or digital. It is electronically
balanced, with the following connections:
Pin 1: Screen.
Pin 2: Phase.
Pin 3: Non-phase.
Reset
Button
Power
LED
The source of this XLR input must be from the audio feed that is the source of
the echo. This is used by the cancelling algorithm to calculate what to remove
from the near end.
Near End Input
An XLR 3 pin socket is used for the NEAR END input channel and it can take
an analogue or AES/EBU digital feed. The input will automatically detect
whether the source is analogue or digital. It is electronically balanced, with
the following connections:
Pin 1: Screen.
Pin 2: Phase.
Pin 3: Non-phase.
The source of this XLR input must be from the audio feed that is
contaminated with the echo. It is from this feed, that the cancelling algorithm
will be subtracting it’s echo estimation to produce an echo free result.
Outputs
Analogue Outputs 1 & 2
The analogue outputs consist of two XLR male connectors professionally
balanced with following connections:
Pin 1: Screen.
Pin 2: Phase.
Pin 3: Non-phase.

5
Connections and Operation 2
Both channels contain the same signal. When using analogue as the input
type, only analogue outputs are enabled.
Digital Output
The digital output is connected using a male XLR connector on the rear
ƉĂŶĞůdŚŝƐy>ZϯƉŝŶƉůƵŐŚĂƐĂŶŝŵƉĞĚĂŶĐĞŽĨϭϭϬɏǁŝƚŚƚŚĞĨŽůůŽǁŝŶŐ
connections:
Pin 1: Screen.
Pin 2: Phase.
Pin 3: Non-phase.
When using analogue as the input type, this output is disabled.
General Note About Inputs & Outputs
The analogue and digital outputs will both be present when digital inputs
are used. The digital output is disabled when an analogue input is used
because it detects the clock from the digital input to detect the input/
output sample rate. However, it it is possible to use different analogue and
digital input configurations for the Near End and Far End inputs.
Settings DIPSwitch
Unit Settings are configured using a 4 way DIPSwitch:
Settings DIPSwitch
1 Far end digital input termination. ON = Terminated, OFF =
Unterminated
2 Near end digital input termination. ON = Terminated, OFF =
Unterminated
3 ON = Bootstrap mode, OFF = Normal mode
4 ON = Disable cancellation (Bypass), OFF = Enable cancellation
Input Termination
ϭϭϬɏŝŶƉƵƚƚĞƌŵŝŶĂƚŝŽŶĨŽƌƚŚĞ^hĚŝŐŝƚĂůŝŶƉƵƚƐĂƌĞĐŽŶƚƌŽůůĞĚďLJƚŚĞ
settings of DIPSwitches 1 and 2, as follows:
SW1:tŚĞŶƐĞƚƚŽKE&ĂƌĞŶĚĚŝŐŝƚĂůŝŶƉƵƚŝƐƚĞƌŵŝŶĂƚĞĚǁŝƚŚϭϭϬɏ
SW2: tŚĞŶƐĞƚƚŽKEEĞĂƌĞŶĚĚŝŐŝƚĂůŝŶƉƵƚŝƐƚĞƌŵŝŶĂƚĞĚǁŝƚŚϭϭϬɏ
Bootstrap Mode
To enable bootstrap mode, power the unit off, switch DIPSwitch 3 to ON
and power up the unit. The RB-AEC can now be programmed with new
firmware.
Warning: This removes the main firmware from the unit and should not
be necessary unless the unit has been loaded with incorrect or corrupt
Analogue &
Digital Inputs
Analogue
Outputs
Digital
Output Settings Ethernet Port Fuse Mains Input
Fig 2-2: The RB-AEC Rear Panel
GPIO
Connector

6
2 Connections and Operation
firmware. Once in Bootstrap Mode you will need to load main firmware
into the device using a standalone application. Contact Sonifex for more
information.
Bypass Cancellation
To test whether the product is effective in your application, you can
configure it and then toggle DIPSwitch 4 to listen to the effect with (OFF)
and bypassed without (ON) cancellation.
GPIO Connector
This a 9 way D-type socket with the following connection details:
GPIO Pin
Pin No Signal I/O Description
Pin 1 GPO1 O General purpose output 1 - Power good
Pin 2 GPO2 O General purpose output 2
Pin 3 GPO3 O General purpose output 3
Pin 4 GPI1 I General purpose input 1 - Mute input detect
Pin 5 GPI2 I General purpose input 2
Pin 6 GPI3 I General purpose input 3
Pin 7 12VDC - 50mA fused +12V power supply
Pin 8 DGND - Ground return for external circuits
Pin 9 DGND - Ground return for external circuits
Power Good
Pin 1 shows a power fail condition. This open collector output is normally
HIGH. Should a power failure occur, this level will go low (DGND).
Mute Input Detect
Setting the mute input detect pin 4 to DGND 0V will disable adaption.
This may prevent the canceller from becoming unstable when the input is
muted.
Ethernet Port
The Ethernet port is connected using a standard RJ-45 connector on the
rear of the panel. It is a 10/100Mbps link. The unit can be controlled
remotely over the Ethernet connection using the built-in webserver. By
default the unit is configured for dynamic addressing using DHCP and Auto-
IP. If a static IP address is required then this must be configured through the
webserver.
The connections for the RJ45 connector are as follows:
Ethernet Connector (RJ-45)
Pin No. Function
Pin 1 Transmit data (+)
Pin 2 Transmit data (-)
Pin 3 Receive data (+)
Pin 4 No connection
Pin 5 No connection
Pin 6 Receive data (-)
Pin 7 No connection
Pin 8 No connection
Mains Power
Power is applied via a standard three-pin IEC male socket. Mains voltages
between 85V and 264V AC and frequencies between 47 and 63Hz are
accepted without adjustment.
A 2A, 5 x 20mm SB fuse is used. The Earth pin MUST be connected to
ensure safety.

7
Applications 3
Applications
How to Remove Delayed Presenter’s Audio From
Their Earpiece
The Problem:
Microphone audio from the presenter(s) is played aloud in the control
room/gallery, where a live microphone allows the director to talk to the
presenter(s) via their earpiece(s). This live microphone also inadvertently
picks up the presenter’s microphone audio and feeds it back to them in
delay, causing a disconcerting self-echo in their earpiece.
The Solution:
1. Connect the director’s microphone signal (at line level) to the RB-AEC
near-end input.
2. Connect the gallery monitor signal (at line level, containing the
presenter’s microphone audio) to the RB-AEC far-end input.
3. Connect the RB-AEC output(s) to the presenter’s earpiece(s). Turn on the
RB-AEC.
4. Allow the presenter(s) to talk for 1 minute without the director using
their microphone (though it must still be active). The RB-AEC will
learn the environment and the echo will gradually disappear from the
presenter’s earpiece(s). The coefficients are stored and loaded on power-
up. This process will not need repeating unless the environment changes.
Studio
Control Room/
Gallery
Amp
M
Amp Line Level
Line Level
To Presenter’s
Earpiece

3 Applications
8
How to Remove Delayed Caller Audio From The
Telephone Line
The Problem:
Caller audio from the telephone hybrid is played aloud in the TV studio,
where live microphones are fitted to presenters and guests (boundary
microphones may also be present). These live microphones also
inadvertently pick up the caller’s audio and feed it back to them in delay,
causing an undesirable self-echo.
TV Studio
Sound Studio
Amp Amp
Telephone Line
Studio Mics
(Presenter/Guest/Boundary)
Line Level Line Level
The Solution:
1. Connect the mixed studio microphones signal (at line level) to the RB-
AEC near-end input.
2. Connect the TBU output to the RB-AEC far-end input.
3. Connect the RB-AEC output(s) to the hybrid’s input (in line mode). Turn
on the RB-AEC.
4. Make a test call and allow the caller to talk for 1 minute, their voice
played aloud through the studio monitor and being picked up by all
studio microphones (which should be in-position and active but not
being used). The RB-AEC will learn the environment and the echo will
gradually disappear from the phone line. The coefficients are stored and
loaded on power-up. This process will not need repeating unless the
environment changes.

9
Applications 3
Calibration
When using the RB-AEC for the first time, the unit must first be calibrated
to suit the environment in which it will be used. Using the webserver, select
the ‘Config’ tab.
1. Select the desired sample rate.
2. Measure the distance between the speaker and microphone in
centimetres. Halve this number and enter it here. Example: For a
distance of 100cm, enter 50. Otherwise leave this value at zero.
3. Tick the box labelled ‘Load Saved Coefficients on Startup’. This will ensure
that any saved coefficients are used next time the unit is switched on.
4. Set the presenter’s(Far End) silence detect threshold. Levels below this
value will disable the canceller.
5. You also have the option of enabling the noise gate, setting the threshold
and changing the release time.
6. Submit your settings
7. For calibration, ensure the control room is silent and speak into the
presenter’s microphone while monitoring using the presenter’s earpiece
for around one minute or until the echo has subsided to a satisfactory
level.
8. Save your coefficient values so they can be used as a starting point for
next time the RB-AEC is used.

10
4 Network Discovery and Webserver
The Sonifex device can be detected using the Sonifex Discovery Tool and the
device’s webserver may be launched.
Bonjour is available as standard on MAC OS and as plug-in for Internet
Explorer for the ‘Bonjour for Windows’ download. You can also use the
discovery application provided by Sonifex and available for download on the
Sonifex website www.sonifex.co.uk
Running The Webserver
Use Google Chrome or Mozilla Firefox browsers and simply type in the
RB-AEC IP address.
Webserver & Unit Discovery
The RB-AEC uses the Zeroconf networking methodology to allow the unit to
be a “plug and play” device. Just simply connect it to the network and use
it. The unit is assigned an IP address using a DHCP server, or a self-assigned
address using AUTOIP when one isn’t available. The RB-AEC can also use
Bonjour discovery on a network.
Once the RB-AEC has been connected to the network, it will try to obtain
an IP address from a DHCP server on the network. If none is found then the
unit will use Auto-IP to assign itself an IP address.
There is no direct method for you to determine exactly which IP address has
been assigned to the unit. However, using a Bonjour discovery application
or browser plug-in, the unit can be discovered and connected to with
relative ease.
Fig 4-1: The RB-AEC Sonifex Service Discovery Tool