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User Guide
Issue Preliminary 2, March 2009
This User Guide is applicable for serial numbers
M45-00151 and later
Copyright © 2009 by Studio Technologies, Inc., all rights reserved
www.studio-tech.com
50216-0309, Issue Preliminary 2
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Table of Contents Introduction ................................................................... 5 Installation ..................................................................... 10 Configuration ................................................................ 16 Operation ...................................................................... 19 Technical Notes ............................................................. 24 Specifications .................................................
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This page intentionally left blank. Issue Preliminary 2, March 2009 Model 45 User Guide Page 4 Studio Technologies, Inc.
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The connected party-line intercom circuit Introduction can also provide the Model 45’s operat- The Model 45 is designed to interface ing power. For maximum flexibility the unit 2-wire full-duplex party-line (PL) intercom is capable of supplying 30 volt DC power circuits with 4-wire audio circuits associ- and AC terminations, thus creating a ated with matrix intercom systems. Appli- 2-wire party-line intercom circuit. This cations for the Model 45 include television allows direct support f
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mode the 30 volt, 300 milliampere maxi- 2-Wire Party-Line Interface mum output can power devices such as The Model 45’s two-channel 2-wire party- user stations and belt packs. In many line interface is optimized for direct connec- applications this will eliminate the need tion with a dual-channel party-line intercom for an external intercom power supply. circuit. In addition, single-channel party- Besides reducing total system cost, this line intercom circuits can also be connect- feature
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of its 2-wire-to-4-wire hybrid circuits. Each highlight that while the nulling process is of the two independent circuits provides automatic, it only takes place upon user low noise and distortion, good frequency request. The parameters obtained during response, and high return-loss (“nulling”), the nulling process are stored in nonvola- even when presented with a wide range tile memory; power interruptions won’t of 2-wire party-line conditions. Unlike tele- require the auto nulling functio
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of only 2 dB is required. The RTS ADAM™ to be essentially identical to that of the series of matrix intercom systems has a unpowered (“dry”) channel. This unique nominal level of +8 dBu. This level also situation allows the automatic nulling applies to their RVON-I/O VoIP products. circuitry to provide excellent, consistent As such, reducing their nominal input and results for both the powered and unpow- output levels by 4 dB will ensure optimal ered channel. compatibility. Attention to det
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audio quality, advanced users might need Design Philosophy to disable it. This would allow full control While the “bits and pieces” that make up over the Model 45’s two hybrid circuits, the Model 45 have been described in con- enabling them to be used in a completely ventional terms, the real strength of the unit independent manner. rests in the way it integrates and performs in the “real world.” Studio Technologies Simple Installation learned from conversations with indus- The Model 45
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The next step was to identify resources getting it ready for use in portable appli- that would improve the installation process cations requires only making a few inter- and make operation more reliable. This connections. These include 4-wire audio led to the use of standard 3-pin XLR-type input, 4-wire audio output, and 2-wire audio connectors, enabling rapid installa- party-line intercom connections that use tion and troubleshooting in any locale. The 3-pin XLR-type connectors. In many ap-
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cables will help to ensure more reliable and front panel, begin the process by remov- consistent intercom system performance. ing the five screws that hold the standard The differential (“balanced”) 4-wire circuits “throw-down” front panel to the Model are typically not impacted by the length of 45’s chassis. Using a Phillips screw driver, their interconnecting cables. A final location remove the 4-40 flat-head Phillips-head criterion is to provide access to the Model machine screw which is
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Once the desired one or two Model 45 and has an impedance of 13 k ohms. The units have been installed in a rack-mount line inputs are optimized for signals that front panel, the assembly can be mounted have a nominal level of +4 dBu. into the designated equipment rack. One Audio sources are connected to the line space (“1U” or 1.75 vertical inches) in inputs by way of 3-pin female XLR-type a standard 19-inch equipment rack is connectors which are located on the required. Secure the uni
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unbalanced source in this manner results 45’s 2-wire party-line interface can also in hum or noise, connect XLR pin 2 to high serve as an intercom power source and (+ or hot) and pin 3 to shield; leave pin 1 200 ohm impedance generator, allowing unterminated. intercom user devices to be directly con- nected. The Model 45’s internal 30 volt 4-Wire Line Outputs DC intercom power source is limited to The Model 45’s dual-channel interface pro- 300 milliamperes of current. This moder- vides two
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pin 3 of the Model 45’s 2-wire party-line intercom interface, will be utilized. Pin 2, the Model 45’s audio channel 1, will only be used for connecting DC power to the connected devices. While the audio resourc- es provided by channel 1 will not be used, the Model 45 can still be used to supply DC power on pin 2. As previously mentioned, Figure 5. Adapter cable wiring diagram the maximum current draw on the 30 volt DC output is 300 milliamperes. Alternatively, must be set to its of
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External 24 Volts as the Power Source configuration DIP switch 1 must be in its on (up) position. Please refer to the Con- As previously discussed, the Model 45 can figuration section of this user guide for be powered by a source of 24 volts DC. A additional details. “locking” 2.1 x 5.5 mm coaxial power jack is located on the back panel of the unit. Before blithely going ahead and powering The center pin of the jack is the positive (+) the Model 45 with a party-line circuit, it’s conn
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drop can become appreciable in situations Using the Connected 2-Wire where belt pack operation wouldn’t nor- Party-Line Circuit as the mally be impacted. Performing accurate Model 45’s Power Source calculations in this scenario is a bit more difficult but might be required to ensure a Configuration DIP switch 1 is used to reliable installation. select whether or not the connected 2-wire intercom circuit can be used to provide Initial Operation power for the Model 45. When the switch i
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external source of 24 volts is going to be in its off (down) position the Model 45 will connected switch 1 should be placed in not serve as an intercom power source. its off (down) position. This ensures that a This setting is appropriate when an exter- failure of the connected 24 volt DC source nal intercom power supply is providing won’t cause the Model 45 to automatically power and terminations to the connected revert to pulling power from the intercom 2-wire intercom user devices. When s
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interface to be auto nulled at approxi- single-channel intercom circuit are con- mately the same time. The dual auto null nected to the Model 45. In this latter case mode allows a single “tap” of the button to only one of the Model 45’s audio channels initiate nulling of both hybrid circuits. will be used. When configuration DIP switch 3 is in its There may be situations where it’s neces- on (up) position the independent auto null sary for the two channels associated with mode is selected. Th
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the Model 45’s 2-wire-to-4-wire converter completion, the applicable input power circuitry. These audio artifacts will not LED will light. The null settings for the two cause any damage but will be sent out of hybrid circuits are recalled and used, hav- the 4-wire line outputs. Users of the 4-wire ing been previously stored in nonvolatile equipment may be less than pleased with memory. what they hear! Significant user intervention is typically not required during normal Model 45 opera- 4-Wir
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are fully isolated from the 2-wire intercom When the Model 45 is Serving as the circuit. In this situation the Model 45’s only 2-Wire Intercom Power Source function is to route, by way of the hybrids, When configuration DIP switch 2 is set the 2-wire interface’s audio signals to and so that the Model 45 provides 2-wire (PL) from the 4-wire outputs and inputs. In this power its interface supplies 30 volts DC mode of operation the Model 45 acts as a on pin 2 of the 2-wire (PL) intercom co
