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Denna manual är också lämplig för
ACOUSTIC ECHO CANCELLER CARD
MY4
-
AEC
Owner’s Manual
Bedienungsanleitung
Mode d’emploi
Manual de instrucciones
Manuale di istruzioni
Руководство пользователя
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ZH
RU
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DE
EN
ENGLISHDEUTSCHFRANÇAISESPAÑOLITALIANO
MY4
-
AEC
ACOUSTIC ECHO CANCELLER CARD
FCC INFORMATION (U.S.A.)
1. IMPORTANT NOTICE: DO NOT MODIFY THIS UNIT!
This product, when installed as indicated in the
instructions contained in this manual, meets FCC
requirements. Modifications not expressly approved by
Yamaha may void your authority, granted by the FCC, to
use the product.
2. IMPORTANT: When connecting this product to
accessories and/or another product use only high
quality shielded cables. Cable/s supplied with this
product MUST be used. Follow all installation
instructions. Failure to follow instructions could void
your FCC authorization to use this product in the USA.
3. NOTE: This product has been tested and found to
comply with the requirements listed in FCC Regulations,
Part 15 for Class “B” digital devices. Compliance with
these requirements provides a reasonable level of
assurance that your use of this product in a residential
environment will not result in harmful interference with
other electronic devices. This equipment generates/uses
radio frequencies and, if not installed and used
according to the instructions found in the users manual,
may cause interference harmful to the operation of
other electronic devices. Compliance with FCC
* This applies only to products distributed by YAMAHA CORPORATION OF AMERICA. (class B)
regulations does not guarantee that interference will not
occur in all installations. If this product is found to be
the source of interference, which can be determined by
turning the unit “OFF” and “ON”, please try to eliminate
the problem by using one of the following measures:
Relocate either this product or the device that is being
affected by the interference.
Utilize power outlets that are on different branch (circuit
breaker or fuse) circuits or install AC line filter/s.
In the case of radio or TV interference, relocate/reorient
the antenna. If the antenna lead-in is 300 ohm ribbon
lead, change the lead-in to co-axial type cable.
If these corrective measures do not produce
satisfactory results, please contact the local retailer
authorized to distribute this type of product. If you can
not locate the appropriate retailer, please contact
Yamaha Corporation of America, Electronic Service
Division, 6600 Orangethorpe Ave, Buena Park, CA90620
The above statements apply ONLY to those products
distributed by Yamaha Corporation of America or its
subsidiaries.
CANADA
This Class B digital apparatus complies with Canadian ICES-003.
Cet appareil numérique de la classe B est conforme à la norme NMB-003 du Canada.
• This applies only to products distributed by Yamaha Canada Music Ltd. (class B)
• Ceci ne s’applique qu’aux produits distribués par Yamaha Canada Musique Ltée.
This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions:
(1) this device may not cause harmful interference, and (2) this device must accept any interference received, including
interference that may cause undesired operation.
이 기기는 가정용(B급) 전자파적합기기로서 주로 가정에서 사용하는 것을 목적으로 하며, 모든
지역에서 사용할 수 있습니다.
(class b korea)
MY4-AEC Owner’s Manual 3
PRECAUTIONS
PLEASE READ CAREFULLY BEFORE
PROCEEDING
* Please keep this manual in a safe place for
future reference.
WARNING
Always follow the basic precautions listed below to
avoid the possibility of serious injury or even death
from electrical shock, short-circuiting, damages,
fire or other hazards. These precautions include, but
are not limited to, the following:
• Do not install the card in any Yamaha products not
specified by Yamaha for use with the card to avoid possible
electrical shock, fire, or equipment damage.
• Do not attempt to disassemble or modify the card. Do not
apply excessive force to card connectors or other card
components. Mishandling of the card may lead to shock,
fire hazard, or equipment failure.
• Be sure to disconnect the power cable of the host device
before installing the card and connecting/disconnecting the
cables (in order to eliminate shock hazard, undesired noise,
and avoid equipment damage).
• Turn off all peripheral devices connected to the host device
before installation, and unplug all related cables (in order
to eliminate shock hazard, undesired noise, and avoid
equipment damage).
CAUTION
Always follow the basic precautions listed below to
avoid the possibility of physical injury to you or
others, or damage to the device or other property.
These precautions include, but are not limited to,
the following:
• Be sure to properly ground the host device to prevent
electrical shock and/or malfunction.
• Do not touch the metallic leads (pins) of the circuit board
when handling the card. The pins are sharp and may cause
hand cuts.
• Wear a pair of heavy gloves during installation to avoid
scratching or cutting your hands on sharp edges.
• Avoid touching exposed connectors and metal parts to
minimize the possibility of bad connections.
• Drain all static electricity from your clothing and body
before handling the card. Static electricity can damage the
card. Touch an exposed metal part of the host device or
other grounded object beforehand.
• Do not drop the card or subject it to physical shock as this
can result in breakage and/or malfunction.
• Do not drop screws or other small parts inside the card. If
power is applied while screws or similar metal objects are
loose inside the unit the card may malfunction or be
damaged. If you cannot retrieve dropped objects yourself,
refer the problem to qualified Yamaha service personnel.
Yamaha cannot be held responsible for damage caused by
improper use or modifications to the device, or data that is
lost or destroyed.
• The illustrations as shown in this manual are for
instructional purposes only, and may be different from the
ones on your equipment.
• The company names and product names in this manual are
the trademarks or registered trademarks of their respective
companies.
4 MY4-AEC Owner’s Manual
Information for Users on Collection and Disposal of Old Equipment
This symbol on the products, packaging, and/or accompanying documents
means that used electrical and electronic products should not be mixed with
general household waste.
For proper treatment, recovery and recycling of old products, please take them
to applicable collection points, in accordance with your national legislation and
the Directives 2002/96/EC.
By disposing of these products correctly, you will help to save valuable
resources and prevent any potential negative effects on human health and the
environment which could otherwise arise from inappropriate waste handling.
For more information about collection and recycling of old products, please contact your local
municipality, your waste disposal service or the point of sale where you purchased the items.
[For business users in the European Union]
If you wish to discard electrical and electronic equipment, please contact your dealer or supplier
for further information.
[Information on Disposal in other Countries outside the European Union]
This symbol is only valid in the European Union. If you wish to discard these items, please contact
your local authorities or dealer and ask for the correct method of disposal.
European models
Purchaser/User Information specified in EN55103-1 and EN55103-2.
Conforms to Environments: E1, E2, E3 and E4
MY4-AEC Owner’s Manual 5
Introduction
Thank you for choosing the Yamaha MY4-AEC. The MY4-AEC is an acoustic echo canceller
card designed for use with the DME64N/24N Digital Mixing Engines that can effectively reduce
troublesome acoustic echoes due to secondary pickup of speaker output and reflections from
room surfaces in teleconferencing situations. It is also capable of reducing feedback as well as
ambient noise from air conditioning and fans. This technology enables noise-free, high-
intelligibility teleconferencing in just about any environment. Four AES/EBU input and output
channels are provided, all with built-in sample rate conversion capability. The MY4-AEC can
also connect to digital audio devices that do not allow word clock synchronization.
Refer to the DME64N/24N owner’s manual for installation details. The screws on the left and
right sides of the card also ground (earth) the device, so be sure to tighten them securely.
Owner’s Manual (this document)
3-pin Euroblock plugs x 4
Cable ties x 4
Installation
Supplied Items
6 MY4-AEC Owner’s Manual
Principle of Operation
How Acoustic Echo and Noise are Reduced
Acoustic echo occurs in a teleconferencing system when the sound from a speaker or
reflections from surfaces of the room are picked up by a microphone and transmitted to the
other party, resulting in a loss of intelligibility. Projectors and air conditioning systems also
produce noise that can interfere with clear teleconferencing. The echo cancelling and noise
reduction capabilities of the MY4-AEC help to achieve maximum clarity and intelligibility for
smooth, effective communication.
NOTE
In order to reduce acoustic echo originating from the remote location, an echo canceller must be
installed and active at the remote location.
HOME UTILITYSCENE LEVEL MUTE
ENTERCANCEL
“Hello”
Remote Local
“Hello”
“How’s business?”
Fan noise
“How’s business”
+ “Hello”
+ fan noise
“How’s business?”
DME64N/24N
MY4-AEC
+
MY4-AEC Owner’s Manual 7
MY4-AEC Signal Flow
The local and remote locations in a teleconferencing system are referred to as the “near end”
and “far end”, respectively. The MY4-AEC acoustic echo canceller (AEC) works by comparing
the reference signal received from the far-end with the signal from the microphone in order to
determine which components of the signal are echo, and then subtracts only the far-end echo
component from microphone signal. The near-end sound is thus clearly transmitted to the far
end without echo.
Reference signal FBS: Feedback suppressor NR: Noise reduction
From Far
-
end A Far
-
end Voice A
NR
From Far
-
end B Far
-
end Voice B
NR
From Far
-
end C Far
-
end Voice C
NR
From Far
-
end D Far
-
end Voice D
NR
To Far
-
end 4
Near
-
end Mic. 4
Near
-
end Voice 4
NR
FBS
To Far
-
end 3
Near
-
end Mic. 3
Near
-
end Voice 3
NR
FBS
To Far
-
end 2
Near
-
end Mic. 2
Near
-
end Voice 2
NR
FBS
To Far
-
end 1
Near
-
end Mic. 1
Near
-
end Voice 1
NR
FBS
AEC
AEC
AEC
AEC
Matrix Router
8 MY4-AEC Owner’s Manual
The Connectors and Their Functions
AES/EBU IN and OUT Connectors
These connectors support four channels of AES/EBU format digital audio input and output to
and from the host DME64N/24N unit, but those signals are not directly routed via the MY4-AEC
processing section. Signals from the host’s analog or digital inputs must be routed to the MY4-
AEC card’s AEC processing section via the host’s processing section in order to apply echo
cancellation, as shown in the illustration below. Operational details are provided in the DME
Designer owner’s manual. Built-in sample rate conversion is provided for all inputs and outputs
(sample rate conversion settings are also made via the DME Designer software).
Use the supplied Euroblock plugs for connection (refer to “Euroblock Connection” on
page 10).
NOTE
The channel 3 and channel 4 inputs and outputs ([IN3/4] and [OUT3/4] in the above illustration)
cannot be used when the DME64N/24N word clock sampling rate is set to 88.2 kHz or 96 kHz.
MY4-AEC Owner’s Manual 9
DME Processing
DME64N/24N
MY4-AEC
AEC
Processing
SRC SRC
AES/EBU
[OUT1/2][OUT3/4]
AES/EBU
[IN1/2][IN3/4]
Analog Out Mic In
10 MY4-AEC Owner’s Manual
Euroblock Connection
Please be sure to use the supplied Euroblock plugs to connect the AES/EBU [IN] and [OUT]
connectors.
Cable preparation
• To prepare the cable for attachment to a Euroblock
connector, strip the wire as shown in the illustration
using stranded wire to make connections. With a
Euroblock connection, stranded wires may be prone to
breakage because of metal fatigue due to the weight of
the cable or due to vibration. Bundle the cables and the
Euroblock tabs using the supplied cable ties (page 12). When rackmounting your
equipment, use a lacing bar when possible to bundle and fasten the cables.
NOTE
Do not tin (plate with solder) the exposed end.
• If cables will be frequently connected and
disconnected, as in the case of a portable installation,
we recommend that you use ferrules with insulation
sleeves. Use a ferrule whose conductor portion has an
external diameter of 1.6 mm or less, and a length of
approximately 7 mm (such as the AI0,5-6WH made by
the Phoenix Contact corporation).
approx.
7 mm
1.6 mm or less
approx.
7 mm
MY4-AEC Owner’s Manual 11
1 Loosen terminal screws.
NOTE
A slotted screwdriver with a blade width of
about 3 millimeters is recommended.
2 Insert cables.
3 Securely tighten terminal
screws.
Pull the cables (not too strongly) to
confirm that they are securely
connected.
Loosen.
Slotted
Screwdriver
Terminal
Screw
Euroblock
Plug
Tab
3mm or less
+
–
G
12 MY4-AEC Owner’s Manual
4 Bundle the cables and the
Euroblock tab using the
supplied cable tie.
NOTE
Trim any excess part of the cable tie as
necessary.
5 Insert the Euroblock plug into
the AES/EBU [IN] or [OUT]
connector of the MY4-AEC.
MY4-AEC Owner’s Manual 13
Basic Connection and Setup
This is an example of a teleconferencing system set up to allow multiple participants to hold
conferences with a remote location (“Office X”).
The first step is to make the basic local (near end) connections and determine the optimum
microphone and speaker locations as well as gain settings. The AEC system will have the best
possible effect if these initial steps are carried out properly.
1 Prepare the following equipment.
DME24N x 1
MY4-AEC x 1
Microphones x 4
Speakers x 2
NOTE
Be sure to choose microphones and speakers that have good frequency response characteristics
in order to ensure optimum AEC operation.
2 Connect the microphones and speakers to the analog [IN] and [OUT]
connectors on the DME24N rear panel as shown in the diagram.
Example 1: Teleconferencing with a Remote Location
Preparation
14 MY4-AEC Owner’s Manual
3 Make the required virtual connections in the DME Designer configuration
window.
• Connect the signals from microphone inputs 1 – 4 to the “Near-end Mic. 1” – “Near-end
Mic. 4” inputs on the AEC component.
• Place an oscillator that will be used for AEC adjustment in the configuration window and
connect it to the AEC component “From Far-end A” input.
• The “Far-end voice A” output is connected to the conference room speakers (SP 1 and
SP 2) in parallel.
Meeting Room (Near End)
Speaker 1
Speaker 2
Microphone 1
Microphone 2
Microphone 3
Microphone 4
IN (Analog)
OUT
(Analog)
DME24N
MY4-AEC
+
MY4-AEC Owner’s Manual 15
4 Speak into the microphones as you would during an actual conference
and adjust the input gain of each channel.
Adjust the DME24N HA Gain while watching the “Mic. In” meters in the AEC component
editor so that the yellow segment lights only occasionally.
NOTE
AEC may not function properly if the gain is set too high.
16 MY4-AEC Owner’s Manual
5 Open the Oscillator component editor, set the Wave Form type to “Pink,”
and engage the Output section “On” button.
Go back to the AEC component editor and, while watching the “Ref. In” meter, adjust the
oscillator output level so that the yellow segment lights only occasionally.
MY4-AEC Owner’s Manual 17
6 Check that the ERL (Echo Return Loss) meter in the AEC component is
moving.
If this meter is moving over a wide range it means that a large portion of the pink noise
being output from the speaker is being picked up by the corresponding microphone, and
therefore a large amount of echo will be transmitted to the remote location. Carefully adjust
the positions and pickup directions of the four microphones in relation to the speakers in
order to reduce this echo level as much as possible. The more you can reduce the echo at
this stage, the more effective the AEC will be.
NOTE
• If the local meeting room is very reflective or reverberant, it may be difficult to reduce the echo
level sufficiently by simply repositioning the microphones and speakers. In such cases it may
be necessary to apply acoustic panels to the walls or use other means to reduce room
reflections.
• If only the green segment of the ERL meter lights, setting the “Effect” parameter to 1 or 2 should
be optimum, but if the yellow segment of the ERL meter lights an “Effect” setting of 3 or 4 will be
required to produce the best results. Since the actual effectiveness of the processing will
depend on the rooms in which it is used it is important make adjustments while actually
connected to and conferring with the remote location.
• If the input signal becomes distorted for any reason before it reaches the Near-end Mic. 1 – 4
inputs of the AEC component, echo cancelling will not function properly.
7 Enter the microphone-to-speaker distance in meters into the Acoustic
Echo Canceller section “Distance” field.
If multiple speakers are used, enter the distance between the microphone and nearest
speaker for each channel.
If the distance is less than 2 meters, use the default value of “2”. For greater distances
enter the appropriate value.
18 MY4-AEC Owner’s Manual
1 Connect the microphones, speakers, and teleconferencing system to the
analog [IN] and [OUT] connectors on the rear panel of the DME24N as
shown in the diagram.
Four microphones can be connected at the near-end location, allowing multiple
conference participants.
Remote Connection and Settings
Meeting Room (Near End)
Microphone 1
Speaker 1
OUT
(Analog)
IN/OUT (Analog)
IN (Analog)
Office X
(Remote –
Far End)
Network
Teleconferencing system
Microphone 2
Microphone 3
Microphone 4
DME24N
MY4-AEC
+
Speaker 2
MY4-AEC Owner’s Manual 19
2 Make the required virtual connections in the DME Designer configuration
window.
• Connect the signal from the four local microphones (Mic1 – Mic4) and the audio signal
from the remote location (From Office X) to the appropriate inputs of the AEC
component.
• Mix the “Near-end Voice 1” – “Near-end Voice 4” outputs and the “Far-end Voice A”
outputs from the AEC component and connect the mixed output in parallel to the
meeting room speakers (SP 1 and SP 2).
• Mix the “To Far-end 1” – “To Far-end 4” outputs from the AEC component and connect
the mixed output to “To Office X” for transmission to the remote location.
HINT
When multiple speakers are being used in the local meeting room, be sure to connect the
mixed signal to them in parallel. AEC may not function properly if the output balance
between the speakers changes.
20 MY4-AEC Owner’s Manual
3 Adjust the DME Designer AEC component editor parameters so that
acoustic echo is effectively cancelled from the audio signal sent to Office
X.
Begin by checking that the connection with Office X is working properly and that
conversation is possible. If echo can be heard with the default AEC section Effect setting
of “1”, try increasing the setting in small increments. Echo cancellation efficiency will
increase as the setting is increased, but sound quality will decrease at the same time so it
is necessary to find the best setting for conditions in the local meeting room while actually
listening to the audio signal.
Other parameters can usually be left at their default settings. Refer to the DME Designer
owner’s manual for details on the individual AEC component parameters.
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Yamaha MY4-AEC Bruksanvisning
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