User Guide Issue 2, September 2007 This User Guide is applicable for serial numbers: M46-00180 and later and units upgraded with software version 1.3 and higher Copyright © 2007 by Studio Technologies, Inc., all rights reserved www.studio-tech.
This page intentionally left blank.
Table of Contents Introduction ................................................................... 5 Installation ..................................................................... 10 Configuration ................................................................ 16 Advanced Configuration ............................................... 18 Operation ...................................................................... 20 Advanced Operation .....................................................
This page intentionally left blank. Issue 2, September 2007 Page 4 Model 46 User Guide Studio Technologies, Inc.
Introduction The Model 46 is designed to interface 2-wire full-duplex party-line intercom circuits with 4-wire audio circuits associated with matrix intercom systems. Other specialized audio system interfacing applications can also be supported. The Model 46 provides two independent full-featured 2-channel interfaces. Each interface contains two hybrid circuits which include automatic nulling capability. The analog circuitry, under software control, provides excellent audio quality and high returnloss.
The Model 46’s 2-wire interfaces can correctly function with powered (“wet”) or unpowered (“dry”) intercom circuits. Powered circuits have a DC voltage present, typically provided by power supplies such as the RTS PS31 or Clear-Com PS-232. This DC power, normally 30-32 volts, provides energy for connected devices such as user stations or belt packs. In this type of application the Model 46 is configured to operate in its external 2-wire power source mode.
are especially sensitive to this requirement. The Model 46’s sophisticated auto nulling function uses analog circuitry under microprocessor control to achieve significant trans-hybrid loss. This return-loss “null” is achieved by making a series of adjustments to account for the resistive, inductive, and capacitive conditions that are present on the connected 2-wire party-line circuit.
and out of the unit. Additional LED status indicators are also provided, offering a clear view of the 2-wire DC power and auto null functions. Pro Audio Quality The Model 46’s audio circuitry was designed in the spirit of professional audio equipment, rather than that found in typical party-line intercom gear. High-performance components are used throughout, providing low-distortion, low-noise, and high headroom.
Simple Installation The Model 46 uses standard 3-pin XLRtype connectors to allow convenient interconnection in most broadcast and general audio environments. For flexibility, access to the 2-wire party-line intercom interfaces can be made using the connectors provided on both the front and back panels. In permanent installations the back-panel connectors will typically be utilized.
typically connected to 2-wire party-line circuits. By adding DC power sources to the Model 46’s 2-wire interfaces, the need for external intercom power supplies could often be eliminated. The final step was to create a physical package that would provide significant resources in a form that allowed simple and reliable integration with other equipment. This was accomplished by including two 2-channel interfaces in a one-rack-space enclosure.
connected. The source for these signals will typically be ports on a matrix intercom system. It’s also possible that the signals will come from other devices, such as a fiber optic or copper-based audio transmission system. The 4-wire input circuitry is balanced, capacitor coupled, transformer isolated, and has an impedance of 13 k ohms. The line inputs are compatible with signals that have a nominal level of 0, +4, +6, or +8 dBu.
outputs are capable of driving inputs that have impedances as low as 600 ohms, however connecting to loads of 2 k ohms or greater is preferred. The line outputs are connected by way of 3-pin male XLRtype connectors which are located on the Model 46’s back panel. Refer to Figure 1 for a detailed view. The mating connectors (females) should be prepared so that signal high (+ or hot) is expected on pin 2. Signal low (– or cold) should be expected on pin 3. The cables’ shields can be connected to pin 1.
associated with each Model 46 interface. In these applications one might want to view the Model 46 as providing four 2-wire-to-4-wire interface circuits. The Model 46 can certainly be used in this fashion, but adapter cables will have to be prepared. These adapters will “split” the Model 46’s 2-wire PL intercom connectors into two 3-pin male XLR connectors, one for each audio channel. Pin 1 of the female 3-pin XLR intended to mate with the Model 46 will connect to pin 1 of both 3-pin male XLR connectors.
with a 12 volt DC signal using a 560 ohm, ¼-watt resistor in series with the connection would be appropriate. With a 24 volt DC control signal a series resistor of 1.8 k (1800) ohm is recommended. For correct operation a minimum current of 2 milliamperes is recommended. onto a piece of 10-conductor flat ribbon cable. This ribbon cable can safely exit the Model 46 by laying flat between the chassis and the cover.
is part number A1AXH-1036G-ND which is available from Digi-Key (www.digikey.com). It’s important to ensure that the source of the remote control signals can meet the Model 46’s logic-state and timing requirements. The Model 46 recognizes an idle remote control input as one that has no current flowing through it. An active remote control input is one that has current flowing through it for a minimum of 30 milliseconds.
Connection Neutral (N) Line (L) Earth/Ground (E) Wire Color Light Blue Brown Green/Yellow Safety Warning: The Model 46 does not contain an AC mains disconnect switch. As such, the AC mains cord plug serves as the disconnection device. Safety considerations require that the plug and associated inlet be easily accessible to allow rapid disconnection of AC mains power should it prove necessary. As soon as AC mains power is applied the Model 46 will begin its power-up sequence.
power supply is providing power to the intercom circuit. In addition to power, it’s expected that the external power supply will also provide the required 200 ohm terminating impedance to both pins 2 and 3. When switch 1 is in its on (up) position the Model 46 will provide a 30 volt, 300 milliamperes maximum source of DC power to pin 2 of the 2-wire PL intercom connectors. The Model 46 will also provide 200 ohm terminating impedances for both pin 2 and pin 3 of the party-line connectors.
Advanced Configuration Four DIP switches are provided on the Model 46’s back panel. They allow the two interfaces to be configured for several advanced operating modes. Refer to Figure 7 for a detailed view of these DIP switches. The available modes include auto terminate disable, auto null button operation, refresh disable, and factory test. Figure 7.
The auto terminate disable function should be used only when absolutely necessary; it’s possible that a significant downside could be experienced. With auto terminate disabled it’s important that properly terminated 2-wire party line-intercom circuits be connected to pins 2 or 3 on the Model 46’s 2-wire PL connectors. If they are not connected, it’s likely that audio oscillations, noise, and distortion will be generated in the Model 46’s 2-wire-to-4-wire converter circuitry.
longer passing through this component and on to the 4-wire audio output. Whenever this situation arose the component was not damaged, but restoring the flow of audio required either a power down/power up sequence, an auto null operation, or a change to one of the level configuration DIP switches to take place. While it is very unlikely that this type of ESD event would occur during normal field operation it is of concern for critical Model 46 applications.
completion, the power LED will light steadily. The settings for the four hybrid circuits are stored in non-volatile memory and will be recalled during the power-up process. Level Meters The Model 46 contains eight 5-segment LED level meters. These meters are provided as a support aid during installation, configuration, operation, and troubleshooting. The meters represent the signals coming in from, and going out to, the 4-wire connections.
ADAM system has a published nominal level of +8 dBu, but using its configuration software it’s possible to set panels or ports to a level different than nominal. The best solution in this case is to adjust the intercom system so that its levels comply with its own published nominal. This should, at least in theory, lead to the best system performance, including correct interfacing with the Model 46. But often it’s impossible to “clean up” the levels of a existing system.
external 2-wire power mode the Model 46 is simply an observer; whether intercom power is present on pin 2, pin 3, or both pins 2 and 3 is not significant. mount component technology and have a lower maximum current draw of 65 milliamperes. Four of these “modern” BP325 units can easily be supported. So that the Model 46’s 2-wire-to-4-wire interface circuits remain stable and don’t generate audio artifacts, an auto terminate feature is implemented.
Auto Null Each of the Model 46’s dual-channel interfaces has circuitry to automatically null the two 2-wire-to-4-wire interfaces. Normally this process is performed at the time of initial Model 46 configuration but there’s no reason why “auto nulling” can’t be initiated anytime one desires. The only time that auto null must be performed is if conditions have changed vis-à-vis the intercom user devices and wiring connected to a Model 46 2-wire PL interface connector.
active microphones. While the automatic “mic kill” signal will apply to many user devices it may not apply to all. Muting microphones is significant as obtaining a “deep” null requires that no extraneous signals be present on the intercom circuit. Advanced Operation The Model 46 allows several of the operating parameters to be configured to meet the needs of specific applications. The following paragraphs provide details about the auto terminate disable and factory test modes.
Factory Test Mode Back-panel DIP switch 4 allows a factory test mode to be enabled. During normal operation switch 4 should remain in its off (down) position. When switch 4 is in its on (up) position factory mode is active. Enabling this mode will result in the following operating condition: during an auto null sequence the associated 4-wire output channel will remain active. This will allow the tones associated with the nulling process to be present on the 4-wire output.
To display the Model 46’s software version is very simple. From the powered-down state, press and hold the auto null button associated with interface 1. Apply mains power while continuing to press the button. The normal power-up sequence will not occur but instead one LED will be lit in the column associated with interface 1 and one LED will be lit in the column associated with interface 2. As previously described, these two LEDs represent the unit’s current software version.
Specifications General Audio: 4-Wire Inputs: 4, 2 per interface Frequency Response: ±2 dB 100 Hz to 8 kHz Type: transformer-coupled, capacitor isolated Distortion (THD+N): <0.
Appendix A Interfacing Telex®/RTS® Matrix Intercom Systems with the Model 46 Interface ADAM™ Matrix Intercom System Analog Ports to Model 46 Interface RVON-I/O I/O Connections to Model 46 Interface Model 46 User Guide Studio Technologies, Inc.
Appendix B Interfacing Riedel® Artist™ Matrix Intercom System Analog Ports with the Model 46 Interface Issue 2, September 2007 Page 30 Model 46 User Guide Studio Technologies, Inc.
Appendix C Interfacing Clear-Com® Matrix Intercom System Analog Ports with the Model 46 Interface Model 46 User Guide Studio Technologies, Inc.
