Alesis EC1 User Manual

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ALESIS

EC-1AES/EBU

INTERFACECARD

FOR THE M20 PROFESSIONAL20-BITDIGITAL

RECORDER

OWNERSMANUAL

FIRSTEDITIONVERSION1.00

APPLIES TOM20 OPERATING SOFTWAREVERSION1.11

©1998 ALESISCORPORATION

EC-1AES/EBU Interface, Appendix E

EC-1MANUAL 1.00

APPENDIXE

EC-1AES/EBU

INTERFACE

This document covers only those aspects unique to the EC-1card and

 

should be inserted into the binder with the M20 manual.

 

TABLE OFCONTENTS

 

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-1Connection 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-1is 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

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EC-1AES/EBU Interface, Appendix E

IMPORTANTSAFETYINSTRUCTIONS

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-1as well.

CE DECLARATION OFCONFORMITY

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 801-2:19912nd Edition, 4kV direct,

 

8kV air

 

IEC 801-3:19842; 3V/m150MHz-1GHz

 

IEC 801-4:19881st 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: +44.1462.480000

 

Fax: +44.1462.480800

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EC-1MANUAL 1.00

Appendix E, EC-1AES/EBU Interface

October, 1998

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EC-1AES/EBU Interface, Appendix E

ABOUT THEEC-1

The EC-1is 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). TheEC-1may be installed directly into the M20’s rear panel for simple system integration and flexibility. With theEC-1installed, the M20 can receive and transmit AES/EBU digital audio and digital reference clock.

The EC-1expansion 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-ALESISor 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-1features:

8 channels of AES/EBU digital audio. 8 channels of simultaneous input and output available on XLR jacks.

Simple hookup and operation. TheEC-1is designed to install in the rear panel of the M20 and connects to the main circuit board with the includedmulti-pinribbon 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.

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Appendix E, EC-1AES/EBU Interface

OVERVIEW OFMAINFUNCTIONS

ABOUTAES/EBU DIGITALAUDIO

The AES/EBU protocol is the most common professional standard for transmitting digital audio. It is a two-channelprotocol designed for stereo pairs, so transmitting from theeight-channelADAT 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 samenumbered track, in addition to thealways-activeADAT 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).

DIGITALAUDIOCABLES

AES/EBU is a high-frequencydigital interface with some harmonics of its signal extending into the radio range. Whilehigh-qualitystandard microphone cables may be used, in some situationsspecially-designedcables 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.

FRONTPANELSETUP

After installation, the EC-1card 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.

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EC-1AES/EBU Interface, Appendix E

INSTALLATION

PRECAUTIONS

Install theEC-1only 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 TOM20 MAINCIRCUITBOARD

The EC-1comes with a40-pinflexible cable. The cable should be attached to themulti-pinheader on the card with the blue side of the cable facing away from the XLR connectors.

To connect the EC-1to 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-pinheader on the main circuit board. The header is labeled “J7” and sits to the right of the chip labeled“2-32-0007SMPTE FPGA”. The blue side of the cable should face the front of the M20.

4.Screw the EC-1card 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’spresence.

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Appendix E, EC-1AES/EBU Interface

BASICOPERATION

SELECTINGAES/EBU (I/O CARD) AS THEDIGITALSOURCE

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-1card) is installed in the M20. With theEC-1card 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.

SELECTINGAES/EBU (I/O CARD) AS THECLOCKSOURCE

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 SELECTAES/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-numericin 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 theEC-1card is the only jack connected to an AES/EBU digital audio source (like a DAT recorder). If no other AES/EBUsynchronous 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.

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EC-1AES/EBU Interface, Appendix E

Once again, we must remind you: if independent (non-synchronous)AES/EBU sources are connected to theEC-1card, 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 THEEC-1 IS NOT INSTALLED IN THE MASTERM20:

If the EC-1card 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.

INPUTROUTING USINGAES/EBU (I/O CARD) AS THEDIGITAL

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-1card. AES/EBU routing accommodates a2-,4-,or8-busmixing configuration. You have the following AES/EBU routing choices when the digital source = I/O Card:

Odd/Even (2-busfeed): 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 anodd-numberedtrack, route the signal(s) to bus #1 or left. To record onto aneven-numberedtrack, 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-busfeed): 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-busfeed): Press either the Track 5, 6, 7, or 8 button in Input Routing mode. This is thepower-ondefault, 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.

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EC-1MANUAL 1.00