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Related Manuals for Lexicon 20 - REV 1
Summary of Contents for Lexicon 20 - REV 1
- Page 1 User Guide 20/20 AD 20 Bit A/D Converter...
- Page 2 This publication is protected by copyright and all rights are reserved. No part of it may be reproduced or transmitted by any means or in any form, without express prior consent in writing from Lexicon. Printed in the United States of America...
- Page 3 Failure to comply with these precautions, or with specific warnings elsewhere in these instructions violates safety standards of design manufacture and intended use of the instrument. Lexicon assumes no liability for the customer's failure to comply with these requirements. General definitions of safety symbols used on equipment or GROUND THE INSTRUMENT in manuals.
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Page 4: Table Of Contents
20/20 AD User Guide Contents Introduction Controls and Connectors ..............1 Unpacking • Power • Mounting ............1 Front Panel Controls ................2 The Converter • The Level Meters • The Compressor Synchronization and Output Formatting • Alternate Modes Rear Panel Connectors ..............5 Audio Connections ................ -
Page 5: Introduction
Information on specific data which may be required by any target device should be obtained from the manufacturer. Lexicon has attempted to provide correct information and functional capability corresponding to digital audio standards known and available to us at the time of publication of this document and manufacture of this instrument. -
Page 6: Controls And Connectors
Controls and 20/20 AD User Guide Controls and Connectors Connectors After unpacking the 20/20 AD, save all packing materials in case you ever need Unpacking to ship the unit. Thoroughly inspect the 20/20 AD and packing materials for signs of damage. Report any shipment damage to the carrier at once. The following accessories are included with the 20/20 AD: 1. -
Page 7: Front Panel Controls
Controls and Connectors Lexicon 20/20 AD Front Panel Controls The 20/20 AD front panel controls are divided into three functional groups for conversion, compression, and synchronization/output formatting. Synchronization and Output Formatting Converter Compressor UNBAL THRESH UNBAL THRESH UNBAL THRESH UNBAL... - Page 8 20/20 AD User Guide Controls and Connectors The Level Meters When the compressor is off , the behavior of the level meters is determined by the settings of the 1dB SCALE, and PK HOLD switches. When the compressor is on , pressing DISPLAY will cause gain reduction (in dB) to be displayed on the two right hand meters (2-channel mode) or on all four meters (4-channel mode).
- Page 9 Controls and Connectors Lexicon Synchronization Output Formatting DITHER SAMPLE RATE Selects the type of dither: Selects the sample rate of DITHER WIDE 20 BIT wide bandwidth, 20 bit, or the A/D conversion. This PL DN SAMPLE RATE High Frequency .
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Page 10: Rear Panel Connectors
20/20 AD User Guide Controls and Connectors 20/20 AD Rear Panel Connectors BAL/UNBAL Push on/push off switch. Set button to correspond to input signal type. A mismatch be- tween the input signal and Analog Input the setting of this switch, will AC Power 3-pin XLR connectors. -
Page 11: Audio Connections
Controls and Connectors Lexicon Audio Connections Connectors Signal Mating Connector Description AES/EBU XLR A3M Balanced RS-422 Digital Input AES/EBU XLR A3F Balanced RS-422 Digital Output S/PDIF Unbalanced 75 Consumer Digital Output S/PDIF Consumer Digital Consumer Digital Audio Optical Output Word Clock... - Page 12 20/20 AD User Guide Controls and Connectors Cables This interface requires balanced connections using high-quality, low-capaci- AES/EBU tance, controlled-impedance, data communication, twisted-shielded pair cable. Digital Output Microphone cable may introduce a significant amount of jitter into the signal, causing distortion. S/PDIF Use commercially-available, consumer audio optical cable assemblies.
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Page 13: Using The 20/20 Ad
Using the 20-/20 AD 20/20 AD User Guide Using the 20/20 AD The 20/20 AD has four analog inputs: CH1, CH2, CH3 and CH4. In two-channel Analog Inputs mode, only CH1 and CH2 are used, and the dynamic range of the unit is extended. - Page 14 Using the 20/20 AD Lexicon CAUTION These instructions are for use by qualified personnel only. Before opening the 20/20 AD, REMOVE THE POWER CORD. You may be exposed to hazardous voltages even if power to the unit is turned off.
- Page 15 20/20 AD User Guide Using the 20/20 AD The following figure indicates the locations and factory settings of these jumpers on the board. In their closed positions, the jumpers have their right two (or lower two) pins shunted together. To open a jumper, move the shunting block to the left (or upper) two pins.
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Page 16: Balanced And Unbalanced Input Signals
Using the 20/20 AD Lexicon Balanced and Make sure the BALANCE switches located on the rear panel are set to match the type of input. (OUT=balanced , IN=unbalanced). The red UNBAL lights on Unbalanced the front panel will indicate an error if there is a mismatch between the switch Input Signals setting and the signal type. -
Page 17: Front Panel Adjustments
20/20 AD User Guide Using the 20/20 AD Adjust the front panel Gain knobs until the peak input levels are balanced and Front panel come within a few dB of clipping. For now, make sure that the DISPLAY switch Adjustments in the DIGITAL COMP/LIMITER section is set to OFF. -
Page 18: Synchronization And Sample Rate
Using the 20/20 AD Lexicon Synchronization The 20/20 AD can synchronize to its internally derived sample clock at 44.1kHz or 48kHz, or to an external AES or Word Clock signal, in the range of 41-51kHz. and Sample Rate The EXT SYNC switch allows you to select external Word Clock (WC), external AES (AES), or internal source (WC and AES off). - Page 19 20/20 AD User Guide Using the 20/20 AD Internal and The 20/20 AD is shipped configured for Internal mode. To operate in External External modes mode, press EXT SYNC until the desired sync source (WC or AES) lights. If the selected sync source light flashes and the PRES light is not on, it indicates that there is no signal present as a sync source.
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Page 20: About Dither
Using the 20/20 AD Lexicon Dither is a low-level pseudo-random signal which is added to digital audio to About Dither reduce quantization noise, in effect, by replacing it with a “nicer sounding” noise. If the recorder or workstation which follows the 20/20 AD is capable of recording or processing 20 bits, the DITHER switch should be set to 20 BIT. - Page 21 20/20 AD User Guide Using the 20/20 AD -60.00 -60.00 -70.00 -70.00 -80.00 -80.00 -90.00 -90.00 -100.0 -100.0 -110.0 -110.0 -120.0 -120.0 -130.0 -130.0 -140.0 -140.0 -150.0 -150.0 -160.0 -160.0 2.00k 4.00k 6.00k 8.00k 10.0k 12.0k 14.0k 16.0k 18.0k 20.0k 2.00k 4.00k 6.00k...
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Page 22: Automatic Offset Removal
Using the 20/20 AD Lexicon Automatic Offset DC offsets are created by input amplifiers and A/D converters for a number of reasons. In the 20/20 AD, these typically include temperature changes, Removal changes between 2-channel and 4-channel mode, change of sample rate or sync source, or large adjustments of input level controls. - Page 23 20/20 AD User Guide Using the 20/20 AD Note that the 6dB GAIN setting is given only as an example. Feel free to experiment with any level in this mode. (GAIN settings above 12dB are not available because at that point practically all of the dynamic range of the converter will fit onto 16-bit media.
- Page 24 Using the 20/20 AD Lexicon GAIN -3dB 1.50:1 3.00:1 4.00:1 4.00:1 4.00:1 4.00:1 4.00:1 4.00:1 4.00:1 4.00:1 4.00:1 4.00:1 -6dB 1.20:1 1.50:1 2.00:1 3.00:1 4.00:1 4.00:1 4.00:1 4.00:1 4.00:1 4.00:1 4.00:1 4.00:1 -8dB 1.14:1 1.33:1 1.66:1 2.00:1 2.66:1 4.00:1 4.00:1 4.00:1...
- Page 25 20/20 AD User Guide Using the 20/20 AD When RELEASE is set to 0, the compressor acts like an amplifier with a non- Non-linear linear transfer function. For example, setting GAIN to 6dB and THRESHOLD to Transfer Functions -14dB produces a close approximation of a generic tape saturation curve. This mode is also useful for overload protection of some types of percussive instruments.
- Page 26 Using the 20/20 AD Lexicon To summarize: 1. Set the input levels so that the peak level is a few dB below clipping. 2. Turn on the compressor. 3. Set compressor GAIN to the input level safety margin, and THRESHOLD to 0dB.
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Page 27: Digital Audio Outputs
20/20 AD User Guide Using the 20/20 AD In 2-channel mode, when the LINK switch is off, each of the two channels is LINK compressed independently. When the LINK switch is on, the louder of the two channels sets the amount of compression. This serves the same function as “stereo link”... -
Page 28: Realigning Two Dat Recordings
Using the 20/20 AD Lexicon Realigning Two DAT When recording in 4-channel mode to two DAT recorders, it may be useful to record a "clapper" signal to both DATs to facilitate realignment during post- Recordings production. When you press ALT-LINK, the 20/20 AD will generate 8mS of silence, followed by an 8-cycle 1 kHz square wave burst at -12dBfs This signal is time-aligned on all four output channels. -
Page 29: Specifications
20/20 AD User Guide Specifications Digital Audio Frequency Response Signal Delay Inputs and Outputs (relative to 1kHz) 112 samples +0.1, -0.15dB, 10Hz to -20 kHz (2.54 mS at 44.1kHz AES, S/PDIF: XLR, 3-wire balanced 2.33 mS at 48kHz) RCA, 2-wire MAX Input Level unbalanced coaxial line Optical, optical fiber... - Page 30 3 Oak Park Bedford, MA 01730 USA Tel 781-280-0300 Fax 781-280-0499...