User Guide Issue 3, November 2013 This User Guide is applicable for serial numbers M41-01051 and later Copyright © 2013 by Studio Technologies, Inc., all rights reserved www.studio-tech.
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Table of Contents Introduction ................................................................... 5 Installation ..................................................................... 8 Post-Installation ............................................................. 12 Operation ...................................................................... 13 Troubleshooting ............................................................ 16 Technical Notes .............................................................
This page intentionally left blank. Issue 3, November 2013 Page 4 Model 41 User Guide Studio Technologies, Inc.
Introduction The Model 41 is designed to create broadcast-standard IFB outputs from linelevel audio sources. The unit’s primary application is to interface analog outputs associated with digital matrix intercom systems with broadcast IFB user devices. The Model 41 creates four independent IFB outputs. Each IFB output provides DC power and two analog audio signals to support the connected IFB user devices. The Model 41’s audio quality is excellent; little hiss, hum, or other artifacts are present.
IFB outputs provide an effective means of delivering power and two channels of audio to user devices by means of standard audio cables. These cables, ubiquitous to the audio industry, interface using 3-pin male and female XLR connectors. Using IFB outputs and standard audio cables it’s a simple matter to support user devices such as listen-only beltpacks and announcer’s consoles with no external power source required.
a variety of conditions. Unlike other interface devices that use a common but less-than-ideal circuit topology, a unique IFB output circuit was developed by Studio Technologies to achieve the desired performance goals. The result is a major improvement in effectively supporting IFB user devices over a wide range of conditions. Connected devices can draw up to the maximum 220 milliamperes of current with little drop in DC voltage.
performance. The 200-series units combine a variety of microphone control, headphone monitoring, IFB and intercom system interfacing, and related functions into compact desktop units. Legacy listen-only beltpacks from RTS, including the 4020 and 4030, can also be directly supported. Alternate Applications In addition to broadcast intercom applications, the Model 41 can be used to create high-performance stereo headphone cue systems.
a standard 19-inch (48.3 cm) equipment rack. Secure the unit into the equipment rack using two mounting screws per side. Audio Input Connections The Model 41 has eight line-level audio inputs, arranged as four 2-channel pairs. Each pair serves one of the four IFB outputs. Each IFB output, along with its two associated audio inputs, is completely independent. Literally any analog audio source with a nominal operating level in the area of +4 dBu can be successfully connected.
Signal High (+) Signal Low (–) Shield IFB Output 1-Interrupt 24 12 25 Connections IFB Output 1-Program 10 23 11 IFB Output 2-Interrupt 21 9 22 IFB Output 2-Program 7 20 8 IFB Output 3-Interrupt 18 6 19 IFB Output 3-Program 4 17 5 IFB Output 4-Interrupt 15 3 16 IFB Output 4-Program 1 14 2 Notes: 1) Connector type on Model 41 is 25-pin D-subminiature female. Installer must provide plug (male). Connector uses 4-40 threaded inserts for locking with mating plug.
Figure 5. Detail of back panel showing IFB output connectors The Model 41’s IFB outputs are interfaced using four 3-pin male XLR connectors which are located on the unit’s back panel. The associated interface cables, one for each IFB output, must be terminated with 3-pin female XLR connectors. In most cases the IFB outputs should be wired by way of an input/output (I/O) connector panel rather than directly to the external devices.
AC Mains Power The Model 41 operates directly from AC mains power over the range of 100 to 240 V, 50/60 Hz. Being a “universal input” device, there are no switches to set or jumpers to install to match a location’s nominal AC mains voltage. The Model 41 uses a 3-pin IEC 320 C14 inlet connector to mate with a detachable AC mains cord. All units are supplied with an AC mains cord that has a North-American (NEMA 5-15P) standard plug on one end and an IEC 320 C13 connector on the other end.
system from Riedel, the analog ports have a nominal level of +6 dBu. A 2 dB reduction in their output level would be beneficial. In reality, a signal with a nominal level that deviates somewhat from precisely +4 dBu will be acceptable. But with the flexibility of contemporary computercontrolled intercom systems, there’s no reason why a precisely calibrated system can’t be easily implemented.
Audio Monitoring The dual 5-segment LED level meters allow a direct observation of the audio levels present on pins 2 and 3 of the selected IFB output’s 3-pin XLR connector. In television broadcast settings, the Pin 2 (left) meter will typically display the “interrupt” signal while the Pin 3 (right) meter will display “program.” A quick glance at the meters will give an accurate overall indication of a circuit’s performance.
by one. A delay is built into the channel selection process allowing a user to move, for example, from channel 1 to channel 3. By pressing the button twice in rapid succession channel 2 will be automatically skipped. Unique to the Model 41 is its auto scan feature. Pressing and holding the button for two seconds will cause this feature to begin operation. In this mode the monitor source automatically “steps” through each IFB output, pausing for eight seconds before moving on to the next.
Troubleshooting If you’re having trouble getting the Model 41 up and running, this section may help. If you haven’t read the previous sections of this guide, you should do so before proceeding. If the Model 41 Doesn’t Function At All A source of AC mains power must be connected to the Model 41. The unit is a “universal input” type so that applying power in the range of 100 to 240 volts, 50/60 Hz is acceptable.
Maintaining Correct IFB Output Current Draw Each of the four IFB outputs is designed to provide up to 220 milliamperes of DC current. By design, the IFB outputs are protected so that an overload condition, or even a complete short circuit, should not cause damage. Exceeding 220 milliamperes for more than a few seconds will typically cause the auto shut-down mode to become active. A continuous overload condition will cause the IFB output voltage to cycle through a 4-seconds-on/10seconds-off sequence.
to the pin 2 leads on both connectors. Then connect the meter leads to these two wires. The meter will indicate the DC current being drawn while normal operation of the connected device(s) takes place. Be certain to connect the maximum number of devices that might be powered by the IFB output. That is, measure the worst-case condition and ensure that the load is within the maximum 220 milliamperes output. If possible, leaving a 5- or 10-percent reserve margin is a good practice. Figure 9.
in the connecting cable; the lower the resistance per foot (or meter), the longer the cable can be. (Although cable capacitance affects high-frequency performance, resistance is the limiting factor in this case.) For example, a traditional 20 AWG microphone cable is Belden 8412, which has 10.9 ohms resistance per conductor per 1000 feet. Since we’re using two conductors to carry the signal (pins 1 and 2) you’d get 21.8 ohms per 1000 feet of cable.
be noticed, especially since monitoring is generally done using headsets, headphones, or earpieces. Is it possible to reduce the crosstalk that is created? Absolutely, as long as a nonstandard cable connection is made. This becomes a trade-off between an improved crosstalk figure and ease of installation and use. Using two full pairs can significantly reduce crosstalk. Several connection schemes are possible; the exact one selected will depend on the specific installation and personal technical philosophy.
35 4010 Model 41 30 Voltage (V) 25 20 15 10 5 0 0 50 100 150 200 250 Current (mA) Figure 10. IFB output voltage-current curves for RTS 4000-Series and Model 41 Interface Model 41 User Guide Studio Technologies, Inc.
Specifications General Audio: Monitor Section – Headphone Output: Frequency Response – Pin 2 Output (DC with Channel 1 Audio): +0/–3 dB, 20 Hz-20 kHz; +0/–1 dB, 100 Hz-20 kHz Type: 2-channel (stereo), drives headphones by way of 100 ohm series resistors Frequency Response – Pin 3 Output (Channel 2 Audio): +0/–3 dB, 20 Hz-20 kHz; +0/–1 dB, 100 Hz-20 kHz Maximum Voltage: 8 Vpp, 100 ohm load Distortion (THD+N) – Pin 2 Output: (DC with Channel 1 Audio): 0.
Appendix A Interfacing Riedel® Artist™ Matrix Intercom Systems with the Model 41 Interface Information courtesy of Riedel Communications Inc. Model 41 User Guide Studio Technologies, Inc.
