Alesis ADAT-M20 EC-1 User manual

ALESIS
EC-1 AES/EBU
INTERFACE CARD
FOR THE M20 PROFESSIONAL 20-BIT DIGITAL
RECORDER
OWNER’S MANUAL
FIRST EDITION VERSION 1.00
APPLIES TO M20 OPERATING SOFTWARE VERSION 1.11
1998 ALESIS CORPORATION

EC-1 AES/EBU Interface, Appendix E
EC-1 MANUAL 1.00

EC-1 MANUAL 1.00 E-1
APPENDIX E
EC-1 AES/EBU
INTERFACE
This document covers only those aspects unique to the EC-1 card and
should be inserted into the binder with the M20 manual.
TABLE OF CONTENTS
Important Safety Instructions..............................................................................................................2
Safety symbols used in this product...................................................................................................2
CE Declaration of Conformity.............................................................................................................2
About the EC-1 .....................................................................................................................................4
Overview of Main Functions...............................................................................................................5
About AES/EBU Digital Audio.............................................................................................5
Digital Audio Cables ..............................................................................................................5
Front Panel Setup..................................................................................................................................5
Installation.............................................................................................................................................6
Precautions..............................................................................................................................6
EC-1 Connection to M20 Main Circuit Board.......................................................................6
Basic Operation.....................................................................................................................................7
Selecting AES/EBU (I/O Card) as the Digital Source.........................................................7
Selecting AES/EBU (I/O Card) as the Clock Source...........................................................7
To select AES/EBU as the clock source:...............................................................................7
If the EC-1 is not installed in the master M20:......................................................................8
Input Routing using AES/EBU (I/O Card) as the Digital Source......................................8
If the input selection is analog and AES/EBU simultaneously:..........................................9
Editing input routing when the input selection is analog and AES/EBU
simultaneously:.......................................................................................................................9

EC-1 AES/EBU Interface, Appendix E
E-2EC-1 MANUAL 1.00
IMPORTANT SAFETY INSTRUCTIONS
SAFETY SYMBOLS USED IN THIS PRODUCT
This symbol alerts the user that there are important operating and
maintenance instructions in the literature accompanying this unit.
This symbol warns the user of uninsulated voltage within the
unit that can cause dangerous electric shocks.
All safety warnings in the M20 manual (pages v and vi) apply to the EC-1
as well.
CE DECLARATION OF CONFORMITY
Manufacturer’s Name: Alesis Corporation
Manufacturer’s Address: 1633 26th Street
Santa Monica, CA 90404
USA
declares, that the product:
Product Name: EC-1
Product Type: Expansion Card for Digital Multitrack
Recorder
conforms to the following Standards:
Application of Council Directive: 89/336/EEC; 73/23/EEC
Safety: Exempt from Low Voltage Directive
EMC: EN 55022:1995 Class A, EN50082-1:1992
(IEC 801-2:1991 2nd Edition, 4kV direct,
8kV air
IEC 801-3:1984 2; 3V/m 150MHz-1GHz
IEC 801-4:1988 1st Edition 2; 1kV, 0.5kV)
All tests were performed with fully-shielded
cabling.
European Contact: Sound Technology plc
Letchworth Point
Letchworth
Hertfordshire, SG6 1ND
UNITED KINGDOM
Phone: [phone]
Fax: [phone]

Appendix E, EC-1 AES/EBU Interface
EC-1 MANUAL 1.00 E-3
October, 1998

EC-1 AES/EBU Interface, Appendix E
E-4EC-1 MANUAL 1.00
ABOUT THE EC-1
The EC-1 is an optional AES/EBU protocol expansion card designed exclusively for the
M20. It provides 8 simultaneous channels of AES/EBU digital audio inputs and outputs
via eight XLR type jacks (four input channel pairs and four output channel pairs). The EC-1
may be installed directly into the M20’s rear panel for simple system integration and
flexibility. With the EC-1 installed, the M20 can receive and transmit AES/EBU digital
audio and digital reference clock.
The EC-1 expansion card is designed for use only with M20 software version 1.11
or higher. If your M20 has a lower software version, contact Alesis
Technical Support at (800) 5-ALESIS or visit our web site at
www.alesis.com to download the latest M20 software in the form of a
standard MIDI file. You will find instructions for updating the M20 on
the web site as well.
The EC-1 features:
•8 channels of AES/EBU digital audio. 8 channels of simultaneous input and output
available on XLR jacks.
•Simple hookup and operation. The EC-1 is designed to install in the rear panel of the
M20 and connects to the main circuit board with the included multi-pin ribbon
connector. Once connected, the M20 will detect the card’s presence thereby allowing
digital audio I/O configurations using AES/EBU as the digital audio source with
digital input routing. AES/EBU channel pairs can be selected as a clock source as well.

Appendix E, EC-1 AES/EBU Interface
EC-1 MANUAL 1.00 E-5
OVERVIEW OF MAIN FUNCTIONS
ABOUT AES/EBU DIGITAL AUDIO
The AES/EBU protocol is the most common professional standard for transmitting digital
audio. It is a two-channel protocol designed for stereo pairs, so transmitting from the
eight-channel ADAT M20 requires the use of four sets of AES/EBU jacks: four XLR male
jacks for output, and four XLR female jacks for input. The AES/EBU input jacks may be
routed (or “normalled”) to multiple ADAT tracks using the M20’s INPUT ROUTING
feature. The AES/EBU output jacks are always active, outputting the data from their same-
numbered track, in addition to the always-active ADAT Optical outputs, so it is possible to
output digital signals to several destinations simultaneously. As with all digital audio
interchange formats, AES/EBU transmits audio encoded as numbers, which may only be
received by another digital unit.
Do not plug any AES/EBU signals into an analog audio device (such as a
microphone input). Avoid running AES/EBU signals through a patch bay
or cable snake that also handles analog audio signals. Noise and
improper operation may result.
The AES/EBU protocol has an embedded clock so that the transmitter and receiver can
lock onto the exact same sample rate. In simple setups, this is automatic: the device
receiving AES/EBU simply follows the incoming clock (for example, recording from a
single CD in stereo). But in multitrack applications such as the M20, you must design your
system with the “one clock” limitation in mind.
When recording multiple AES/EBU inputs, all inputs being recorded must be
referenced to the same clock. For example, you cannot record into the
M20 from a CD player, a DAT, and a digital sampler simultaneously,
unless all of these devices are synchronous, i.e., set to use a single
master word clock as their reference. For more information on setting
the clock source, refer to the M20 manual chapter 15, tutorial 3 (Digital
Clock Considerations).
DIGITAL AUDIO CABLES
AES/EBU is a high-frequency digital interface with some harmonics of its signal extending
into the radio range. While high-quality standard microphone cables may be used, in some
situations specially-designed cables may be required. Especially in long cable runs, cable
with a specified impedance of 110 ohms may be required. Check with your dealer for more
information.
FRONT PANEL SETUP
After installation, the EC-1 card can be selected as a digital input source and clock reference
via the M20’s front panel. Input routing can be applied to the AES/EBU input as well. The
AES/EBU outputs are always available, no matter what input source is selected.

EC-1 AES/EBU Interface, Appendix E
E-6EC-1 MANUAL 1.00
INSTALLATION
PRECAUTIONS
Install the EC-1 only if you have had some experience with similar devices
and feel competent to do so. If the following instructions are not clear
to you, have your dealer or a trained technician install it for you.
Hazardous voltages are present within the chassis. Do not remove the top
panel without first unplugging the unit from AC power!
EC-1 CONNECTION TO M20 MAIN CIRCUIT BOARD
The EC-1 comes with a 40-pin flexible cable. The cable should be attached to the multi-pin
header on the card with the blue side of the cable facing away from the XLR connectors.
To connect the EC-1 to the M20:
1. Remove the top panel from the M20. The top panel is held to the rear panel with two
Philips head screws.
2. Remove the expansion slot blank panel from the M20 rear panel. Four screws keep the
blank panel in place. It is best to hold the blank panel in place when removing the
screws to prevent the blank from dropping onto the main circuit board.
3. Insert the ribbon connector into the 40-pin header on the main circuit board. The
header is labeled “J7” and sits to the right of the chip labeled “2-32-0007 SMPTE
FPGA”. The blue side of the cable should face the front of the M20.
4. Screw the EC-1 card into the expansion slot from the inside of the M20. Use the four
screws that held the blank panel in place.
5. Replace the top panel.
To test for proper installation, plug the unit back in to AC power, turn on the M20, and
press the Digital Source button (next to the meter display) until the “DIG SOURCE” group
in the meter display indicates “I/O CARD”. This confirms that the M20 has detected the
EC-1’s presence.

Appendix E, EC-1 AES/EBU Interface
EC-1 MANUAL 1.00 E-7
BASIC OPERATION
SELECTING AES/EBU (I/O CARD) AS THE DIGITAL SOURCE
When using digital inputs, the Digital Source function selects one of three digital input
options. The I/O CARD option will appear in the display only if an I/O card (such as the
Alesis EC-1 card) is installed in the M20. With the EC-1 card installed, pressing the Digital
Source button (next to the meter display) toggles through the available sources, such as
ADAT OPTICAL, TRACK COPY, and I/O CARD. To select AES/EBU as the digital
source, press the Digital Source button until I/O CARD appears in the DIG SOURCE group
of the meter display. Now, when Input Select mode is set to digital input for a given
channel pair (and dependent on how input routing is configured), an AES/EBU input will
be the source for the selected channels.
SELECTING AES/EBU (I/O CARD) AS THE CLOCK SOURCE
If a word clock, video, or optical clock source that is synchronous to AES/EBU digital
audio input is not available, sample clock for the M20 can be derived from any of the four
AES/EBU input channel pairs.
TO SELECT AES/EBU AS THE CLOCK SOURCE:
1. Press the Clock Source button (under the main display) until I/O CARD appears in the
CLOCK SOURCE group of the main display.
2. When I/O Card is selected, the alpha-numeric in the main display will indicate, “AES
Clk Source: Chan 1/2”. This implies that the M20 will look for clock input at the
channel pair 1 and 2 XLR input. If AES/EBU clock input is not detected, the I/O
CARD indicator will flash and the M20’s internal clock will be used until valid
AES/EBU input is detected.
3. To select the AES clock source, use the Up/Down arrows on the keypad. The
selections are Chan 1/2, Chan 3/4, Chan 5/6, or Chan 7/8. As noted earlier, if recording
multiple AES/EBU pairs, their clocks must be synchronous to avoid “ticks” and “pops” or
audio distortion. If you have multiple synchronous inputs (for example, from a single digital
mixer), it does not matter which channel pair is chosen as the clock source.
Example: Suppose you set the digital source to I/O CARD, and set the input selection
for channels 3 and 4 to digital (shown by the “D” illuminated under those channel
meters on the M20). Input 3/4 on the EC-1 card is the only jack connected to an
AES/EBU digital audio source (like a DAT recorder). If no other AES/EBU-
synchronous external clock source is available, I/O CARD must be selected as the
clock source. But when you do this, the clock source I/O CARD indicator flashes,
and audio monitored via the M20 is distorted. Why?
Because there still is not a valid clock. The M20’s default AES/EBU clock source is
channel pair 1/2. But in this example, channel pair 3/4 is the only AES/EBU input
present, so the M20 tries to use its internal clock. Since there is no connection
between the M20’s internal clock and the internal clock of the DAT feeding it in this
case, the numbers that make up the digital transfer are arriving in the wrong
positions, causing the distortion. The cure? Simply set the AES clock source to
“Chan 3/4" (or whatever channels you’re using), or plug the AES/EBU source into
channel pair 1/2.

EC-1 AES/EBU Interface, Appendix E
E-8EC-1 MANUAL 1.00
Once again, we must remind you: if independent (non-synchronous) AES/EBU sources are
connected to the EC-1 card, audio cannot be monitored (or recorded) simultaneously since
the clock for each input channel pair is independent. When monitoring AES/EBU digital
audio from more than one channel pair, all of the AES/EBU sources must be synchronous,
i.e., controlled by the same sample clock.
IF THE EC-1 IS NOT INSTALLED IN THE MASTER M20:
If the EC-1 card is installed in a slave M20 (e.g. ID 2), the only clock source available will be
ADAT (the clock coming in through the ADAT Sync In jack). In this case, AES/EBU input
to the slave must be synchronous to the master (ID 1) M20 to avoid clocking problems.
This is where the use of synchronous word clock (or other applicable external clock source)
into the master M20 is an appropriate solution.
Note: In typical scenarios where ADAT optical is used as the digital input source, the “D”
indicators beneath each channel’s meter segments will remain solid to indicate that digital
audio input for the selected source is present. If ADAT optical signal is not detected, the
“D”s flash as a warning. When a valid external (synchronous) clock source other than I/O
CARD (e.g. WORD CLOCK) is used with an AES/EBU digital audio input, the “D”
indicators will always remain solid even though AES/EBU signal may not be present.
INPUT ROUTING USING AES/EBU (I/O CARD) AS THE DIGITAL
SOURCE
The Input Routing feature of the M20 allows you to go from any input to any track without
the need for repatching. Just as the analog Input Routing feature allows you to do that with
an analog input, you can do the same for AES/EBU inputs from the EC-1 card. AES/EBU
routing accommodates a 2-, 4-, or 8-bus mixing configuration. You have the following
AES/EBU routing choices when the digital source = I/O Card:
•Odd/Even (2-bus feed): Press INPUT ROUTING and either the Track 1 or 2 button.
Input 1 feeds channels 1, 3, 5, 7, and Input 2 feeds channels 2, 4, 6, 8. To record on
an odd-numbered track, route the signal(s) to bus #1 or left. To record onto an
even-numbered track, route the signal(s) to bus #2 or right. By simply putting the
desired track into record, the proper signal will get there, even though it is not
connected directly to the track’s input jack.
•Half & Half (4-bus feed): Press INPUT ROUTING and either the Track 3 or 4
button. Input 1 feeds channels 1, 5; input 2 feeds 2, 6; input 3 feeds 3, 7; input 4
feeds 4, 8). To record on tracks 1 or 5, route the signal(s) to bus #1. Likewise, to
record onto tracks 2 or 6, route the signal(s) to bus #2, and so on.
•One-to-one (8-bus feed): Press either the Track 5, 6, 7, or 8 button in Input Routing
mode. This is the power-on default, where each input feeds its corresponding
channel. To record on track 1, send the signal to mixer bus 1, to record on track 2
send the signal to mixer bus 2, etc. This is also the recommended mode when
feeding the M20 from a mixer channels’ direct outs.

Appendix E, EC-1 AES/EBU Interface
EC-1 MANUAL 1.00 E-9
Note: The above illustrations assume that the source tracks of the M20 are set to receive
digital input (as shown by a “D” under the meter for each track).
IF THE INPUT SELECTION IS ANALOG AND AES/EBU
SIMULTANEOUSLY:
If you have INPUT SELECT configured for analog and AES/EBU input, input routing must
use the one-to-one configuration. This is the case because using any other bus configuration
will route the selected I/O card digital source tracks (e.g. tracks 1 and 2 using odd/even
routing) to all input enabled tracks even when the input enabled tracks are set to analog
input, i.e., all input enabled tracks become I/O card destination tracks.
EDITING INPUT ROUTING WHEN THE INPUT SELECTION IS ANALOG
AND AES/EBU SIMULTANEOUSLY:
If you have INPUT SELECT configured for analog and AES/EBU input, editing the input
routing is limited to selecting I/O card source tracks only. The analog input routing will
not be editable and will follow (be the same as) the I/O Card routing. If the you want to
edit analog input routing, the digital source cannot be I/O Card.
The scenario below describes a mixed signal input using I/O CARD as the digital source:
Example: You are recording a digital submix patched into AES/EBU input pair 1/2
and intend to route this input to channels 3 and 4. You also have an analog submix
patched into the analog inputs for channels 7 and 8. The M20 is configured as
follows: The DIGITAL SOURCE is I/O CARD. INPUT ROUTING uses the
"odd/even" configuration (channels 1 and 2 are the digital source tracks). INPUT
SELECT is set to DIGITAL input for channels 1 through 4; and ANALOG input for
channels 5 through 8. Channels 3, 4, 7 and 8 are input enabled.
Channels 3 and 4 will monitor the AES/EBU input as expected (the “D” under each
meter seems to make this obvious). Channels 7 and 8 will also monitor AES/EBU
input (not the direct analog input) because the M20 is being told to bus channels 1
and 2 to ANY input enabled track(s). You cannot use odd/even or half & half input
routing with AES/EBU input and monitor analog inputs simultaneously. To
monitor the analog inputs for channels 7 and 8 together with AES/EBU input,
INPUT ROUTING must use the one-to-one routing configuration. In this case
however, AES/EBU input into channel pair 1/2 will not route to channels 3 and 4.

EC-1 AES/EBU Interface, Appendix E
E-10 EC-1 MANUAL 1.00