Digidesign 888|24 I/O Audio Interface Installation Guide Digidesign Inc. 3401-A Hillview Avenue Palo Alto, CA 94304 USA tel: 650·842·7900 fax: 650·842·7999 Technical Support (USA) 650·842·6699 650·856·4275 Product Information 650·842·6602 800·333·2137 Fax on Demand 1-888-USE-DIGI (873-3444) World Wide Web www.digidesign.com Digidesign FTP Site ftp.digidesign.
Copyright Communications & Safety Regulation Information This User’s Guide is copyrighted ©1999 by Digidesign, a division of Avid Technology, Inc. (hereafter “Digidesign”), with all rights reserved. Under copyright laws, this manual may not be duplicated in whole or in part without the written consent of Digidesign.
contents Using the 888/24 I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 The 888/24 I/O Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Changing Operating Levels of Individual 888/24 I/O Channels . . . . . . . . . . . . . . . . . . . . . . . . 6 Making Signal Connections to the 888/24 I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
iv 888/24 I/O
Using the 888/24 I/O The 888/24 I/O™ is an 8-channel digital audio interface that features 24-bit analog-todigital, and 24-bit digital-to-analog converters for superior dynamic range, reduced noise floor, and the capability to work with the full 24-bit mixing, editing, processing, and mastering environment of Pro Tools.
Internal This is the 888/24 I/O standard setting. In this mode, the 888/24 I/O sample rate is generated by its internal crystal oscillator (whose frequency is determined by the Sample Rate setting in the Session Setup window). Internal mode should be active whenever the 888/24 I/O is not synchronized to an external clock source. Digital This setting indicates that an AES/EBU or S/PDIF word clock signal is currently the source for the 888/24 I/O sample rate.
3. Sample Rate and 1–2 Format Indicators These LEDs indicate the sample rate of the 888/24 I/O internal crystal oscillator and the digital format (AES/EBU or S/PDIF) of the audio input signal to channels 1 and 2. The choice of digital format for these two channels is made in the Session Setup window or Hardware Setup dialog. Digital input pairs 3–4, 5–6, and 7–8 of the 888/24 I/O are always AES/EBU. Sample Rate is set in the Session Setup window or Hardware dialog in Pro Tools.
To calibrate the input and output levels of the 888/24 I/O to match your mixing console or other devices in your studio, use Calibration Tool (for Pro Tools 4.3.1 and earlier) or use Calibration Mode and the Signal Generator Plug-In (for Pro Tools 5.0 or later). pair is disabled when digital input format is chosen for that channel. ☞ Instructions for calibrating the 888/24 I/O 3. AES/EBU Digital Outputs 1–8 appear in Appendix B of this Guide.
5. 50-pin Interface Connector 7/9. Slave Clock In/Out This 50-pin Computer connector is used to connect the 888/24 I/O to a MIX card, d24 audio card, Disk I/O card, or a DSP Farm card. The necessary cable is supplied with your Audio Interface. If you plan to connect two 888/24 I/O Interfaces to a MIX card or d24 card, a 16-channel peripheral cable adapter is necessary. (This cable is available from your Digidesign dealer.
Changing Operating Levels of Individual 888/24 I/O Channels The 888/24 I/O is factory set to +4 dBu operating levels for input and output. However, the 888/24 I/O allows you to individually switch any of its analog inputs or outputs to either a +4 dBu or –10 dBV operating level by moving internal jumpers on its circuit board. output level adjustment switches +4 dBu or -10 dBV cate the jumper switch for the channel you wish to modify. Gently lift the cap off the 3-pronged connector.
5 With the ribbon cable out of the way you’ll see eight 3-pronged jumper switches, each with a removable cap. Locate the switch for the channel you wish to modify. remove jumper detach ribbon cable +4 Depending on how you plan to use the 888/24 I/O, the way you connect it to your studio will vary.
Setting Up Your Studio The following diagram illustrates a typical studio setup, with the 888/24 I/O connected to a mixing console, effects and other equipment.
To use the 888/24 I/O as a stand alone D/A converter: 1 Make sure that a digital device providing a word clock signal is connected to AES/EBU inputs 1–2 of the 888/24 I/O and turned on. 2 Turn on the 888/24 I/O. The 888/24 I/O will search for a valid word clock or a word clock signal on channels 1–2 of its digital input ports.
8 After you have made the desired changes, replace the top of the 888/24 I/O. 9 Replace the four front panel screws using the hex wrench. 10 Replace the top screws with a Phillips screwdriver. stand alone mode default word clock lock switches AES/EBU or S/PDIF stand alone mode DAC muting switches stand alone mode default sample rate switches 44.1 kHz or 48 kHz Figure 1.
7 Place it in the position corresponding to 3 Using the 1/16 inch hex wrench in- the value that you desire. For an AES/EBU word clock lock port, it should be placed over the right two prongs. For a S/PDIF word clock lock port, it should be placed over the left two prongs. Refer to Figure 1 and 2 for details. cluded with the 888/24 I/O, carefully remove the front four panel screws as noted on the bag containing the hex wrench. 4 Lift the top off of the 888/24 I/O.
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appendix a Technical Specifications General A/D Specifications Analog Inputs/Outputs: SNR (signal-to-noise ratio): ■ Actively balanced XLR connectors, outputs internally switchable between +4 dBu and –10 dBV line levels ■ ≥ 113 dB (balanced, A-weighted) ■ ≥ 110 dB (unweighted) THD: Analog Level Trimming: ■ Accessible from front panel Digital I/O AES/EBU: ■ 8 channel; balanced XLR connectors Digital I/O S/PDIF: ■ 2 channel; coaxial RCA connectors 0.003% –0.
D/A Specifications SNR (signal-to-noise ratio): ■ ≥ 110 dB (balanced, A-weighted) ■ ≥ 107 dB (unweighted) THD: ■ 0.003% –0.01dB @ 1kHz; 20 Hz- 20 kHz (band-limited) Maximum Output Level: ■ +26 dB/channel (bridging loads) Frequency Response: ■ ±1dB, 20 Hz–20 kHz Physical Specifications Power requirements: ■ 90–260 VAC, 47 63 Hz; 30 VA; auto-switching Weight: ■ 7.6 lbs (4.1 kg) Dimensions: ■ 2U external rackmount device 19" x 3.5" x 9.75" (48.26 cm x 8.89 cm x 24.
appendix b Calibrating the 888/24 I/O (Pro Tools 5.0) Before you use the 888/24/I/O Audio Interface, you may want to calibrate its input and output levels to the level of your mixing console. The 888/24 I/O is factory-calibrated so that its input operating level is set to +4 dB nominal with 18 dB headroom nominal at full code, unity gain, making calibration unnecessary for most professional applications.
The Calibration Process Analog To calibrate the input level of an analog device to a mixing console’s output level, you would typically send a 1 kHz tone at 0 VU from the console to the analog deck and align the recording deck’s meters to read 0 VU. ups. You can use these in addition to the calibration procedure given below. ▲ Turn down your monitoring system before beginning calibration. The Signal Generator Plug-In emits a continuous signal when inserted on a track.
12 Create an additional mono auxiliary in- put track for each 888/24 I/O input you want to calibrate. Set the input assignment for each of these auxiliary inputs to its respective 888/24 I/O input. Then set the output of each of these auxiliary inputs to an unused bus pair (for example bus 31–32) so that feedback doesn’t occur when monitoring main outputs 1–2. 13 Connect an external VU meter to each of the 888/24 I/O outputs in turn. (One at a time as you calibrate.
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appendix c Calibrating the 888/24 I/O (Pro Tools 4.x) Before you use the 888/24/I/O Audio Interface, you may want to calibrate its input and output levels to the level of your mixing console. The 888/24 I/O is factory-calibrated so that its input operating level is set to +4 dB nominal with 18 dB headroom nominal at full code, unity gain, making calibration unnecessary for most professional applications.
The Calibration Process Analog To calibrate the input level of an analog device to a mixing console’s output level, you would typically send a 1 kHz tone at 0 VU from the console to the analog deck and align the recording deck’s meters to read 0 VU. Digital With a digital recording device such as the 888/24 I/O, however, in order to allow for headroom, you must align a 0 VU tone from the console to a value less than zero on the 888/24 I/O, by exactly the amount of headroom that you want.
Level Use this to select the output level relative to the Headroom for the audio waveform generator. 2 In the Headroom field, enter the amount Wave Type Use this to select the type of audio waveform generated the waveform generator. 3 Send a 1kHz tone into the 888/24 I/O Output Every Channel If this option is selected and the Oscillator is on, every output will generate an audio waveform signal at the selected frequency.
Using a VU meter If you don't have a sine wave generator or another way to send a 1 kHz tone into the 888/24 I/O at 0 VU, a second alternative is to measure the output level of the 888/24 I/O with a VU meter, such as the kind found on a professional-quality mixing console. To do this, be sure that the outputs of the 888/24 I/O are connected to the VU meters of the console or other device. (On most consoles these inputs are usually the tape returns, or possibly the line inputs.
