Studio Technologies Model 2A Central Controller

Product Code: ST-M2A

Key Features
The IFB Plus Series Model 2A Central Controller from Studio Technologies is a highly integrated, 2-channel IFB (interruptible foldback) unit. It is the main component of the IFB Plus Series which is expressly designed to provide talent cueing for ENG, SNG, OB, and mobile production facilities. It can also find use in fixed installations that need a compact but feature-rich stand-alone IFB system. The performance and features of the Model 2A, along with its companion accessories, reflect the needs of contemporary applications. Only after extensive polling of field production and engineering personnel was the Model 2A's feature group established. We think you'll find it to be a great addition to your facility.
$5,348.32 inc GST
Increase value Decrease value
Qty Each (inc GST) Each
Estimated Lead time 2-4 weeks
  • Features
  • Overview
  • Technical Specs
  • Documents

Studio Technologies Model 2A Central Controller

Mounted in a single space of a 19-inch rack, the Model 2A provides everything required to implement a 2-channel IFB system. Features include multiple program inputs, telephone interfaces, voice-operated (VOX) interrupt, level metres, monitor amplifier output, and an internal interrupt microphone. In addition, up to four Model 22 or Model 24 Access Stations can be connected to a Model 2A, allowing producer or director positions to access the IFB channels. In addition, up to six Model 32A or Model 33A Talent Amplifiers can be connected to a Model 2A. These portable "beltpack" units interconnect with a Model 2A using standard microphone cables. Both DC power and two channels of audio are supplied on just one 3-conductor cable, providing personnel with convenient, reliable access to the two IFB channels.

The Model 2A packs numerous features into a rugged yet lightweight single-rack-space (1U) enclosure. Standard connectors are used throughout, including 3-pin XLR, ¼-inch 2-conductor, 9-position D-subminiature, and modular telephone (RJ11) jacks. A source of 100-240 V, 50/60 hertz is connected via a detachable mains cord and provides power for the Model 2A.

IFB Channels

The Model 2A contains two independent IFB channels. Each channel has individual controls and indicators, including program source select switches, program level control, 5-segment LED level metre, and LED status indicators. The features of one of two identical channels will be highlighted in this paragraph. Six switches allow the four program audio inputs and audio coming from the two telephone interfaces to be selected as program audio sources. A rotary level control allows adjustment of the program audio level relative to that of the non-adjustable interrupt audio level. A 5-segment LED metre displays the level of the composite IFB audio signal. (The composite audio signal is the combination of the selected program audio source(s) and the interrupt audio source(s).) The level metre facilitates the rapid setting of the program level control, as well as providing a general indication of the IFB channel's signal level.

Each channel's composite IFB audio signal (a mix of program and interrupt audio) is sent to four places: a line-level output, the talent amplifier output, telephone interface 2, and the monitor output section. Each line output provides an electronically balanced, line-level signal that interfaces with external equipment via a 3-pin XLR connector. The talent amplifier output provides IFB channel 1 and 2 audio, along with 24 Vdc power on one 3-pin XLR connector. Any combination of up to six Model 32A or Model 33A units can be connected to the talent amplifier output. For application flexibility, the talent amplifier output provides 200 ohm line impedances on both of its output channels. This allows direct connection of not just listen-only devices, such as the Models 32A and 33A, but party-line (PL) user beltpacks as well. In this way popular PL beltpacks, from suppliers such RTS® and Clear-Com®, can be connected and used to create a small PL intercom system that includes IFB listen. A selector switch associated with telephone interface 2 can be used by an operator to send either IFB channel 1 or 2 out the connected phone line. The monitor output section allows loudspeaker monitoring of audio from either IFB channel 1 or 2. (An optional external loudspeaker is required.)

Program Inputs

The Model 2A contains four line-level program inputs. Each can be individually assigned to the two IFB channels, with the ability to assign multiple program inputs to an IFB channel. Program signals enter the unit via four 3-pin XLR connectors located on the unit's back panel. The program inputs are electronically balanced and feature low noise, low distortion, and high common mode signal rejection. Each program input has a trim potentiometre associated with it. The trim pots, accessible from the back panel, allow source signals with a nominal level of –10 to +8 dBu to be correctly utilized.

Program audio is muted whenever interrupt activity is taking place. Solid-state circuitry is used to provide noise-free audio switching with essentially no "clicks" or "pops" added. If desired, a program "dim" rather than a full mute can be implemented by adding two resistors to the Model 2A's circuit board.

For further information please view the attached Datasheet.


We offer a 3 year warranty on this product from its date of purchase. For more information regarding our support, repair and warranty, please download our Warranty Guide here.

Trade Terms
The above item is non-returnable, unless defective. Please ensure part numbers and descriptions are as required before placing this order. If any confirmation or information is required please contact AV Sales on 1800 00 77 80.
Model 2A Central Controller
General Audio Parametres (Program Input to Main Output):
Overall Frequency Response: 20 Hz to 20 kHz, 0.3 dB @ 20 Hz, 0.8 dB @ 20 kHz
Distortion (THD+N): 0.008%
S/N Ratio: 89 dB, ref. +4 dBu nominal
Interrupt Audio Compressor/Limiters: one per IFB channel, studio quality, dual slope, threshold 1 dB above nominal
Access Station: DE-9F (9-pin D-subminiature, female)
Program and Aux Audio Inputs: 3-pin female XLR
Line Outputs: 3-pin male XLR
Talent Amplifier Output: 3-pin male XLR
Telephone Interfaces: 2, RJ11 modular jack (6-position modular with pins 3 and 4 implemented)
Monitor Amplifier Output: -inch, 2-conductor phone jack
AC Mains Input: 3-blade, IEC 320 C14-compatible (mates with IEC 320 C13)
Internal Interrupt Microphone: electret condenser
Program Inputs: 4
Type: electronically balanced, direct coupled
Impedance: 24 k ohms
Level: +4 dBu, nominal, trim adjustable over a range of 10 to +8 dBu
Auxiliary Audio Input:
Type: electronically balanced, direct coupled
Impedance: 24 k ohms
Level: +4 dBu, nominal, trim adjustable over a range of 10 to +8 dBu
Application: used with voice operated (VOX) interrupt function
Line Outputs: 2, 1 per IFB channel
Type: electronically balanced, capacitor coupled, intended to drive 2000 ohm or greater loads
Level: +4 dBu, nominal, +25 dBu maximum
Talent Amplifier Output:
Applications: provides power and audio signals for up to six Model 32A or Model 33A Talent Amplifiers; also allows connection of party-line (PL) intercom beltpacks
Connections: common on pin 1, DC (+24 Vdc nominal) modulated with channel 1 audio ( 10 dBu nominal) on pin 2, and channel 2 audio ( 10 dBu nominal) on pin 3
Output Impedance: 200 ohms nominal from pin 2 to 1; 200 ohms nominal from pin 3 to pin 1; RTS and Clear-Com compatible
Maximum DC output current: 250 mA
Maximum Audio Output Level: +10 dBu
Voice Operated (VOX) Interrupt Function:
Input Source: audio from telephone interface 1, audio from telephone interface 2; or auxiliary audio input, selectable
Output: IFB channel 1 or 2, selectable
Detection Bandpass: 400 to 1400 Hz, nominal
Detect Time: less than 1 mSec
Release Time: 320 mSec, nominal
Telephone Interfaces 1 and 2:
Operating Modes: switch selectable for use with telephone lines or standard balanced or unbalanced audio signals
Receive Audio Level: 15 dBu, nominal, trim adjustable 8 dB
Telephone Line Requirements: 2-wire, loop start, 10 mA loop current minimum
Telephone Line Disconnect: manual, using front-panel switch; automatic, after detection of 250 mSec, nominal, break in loop current
Telephone Line Interface Control: switch on front panel allows manual answer ("off-hook") and manual hang-up ("on-hook") functions
Telephone Interface 2 Additional Features:
Auto Answer (when set for telephone line operation): configurable for 1, 2 or 4 rings or disabled
Audio Routing Control: switch on front panel allows Interface 2 to receive audio, or send IFB channel 1 or 2 audio
Send Audio Level: 6 dBu, nominal
Monitor Output:
Power: 4 watts RMS into 8 ohms @ 1% THD+Noise
Application: designed to drive loads of 8 ohms or greater
Access Station Interface: allows connection of up to four Model 22 or Model 24 Access Stations
AC Mains Input: 100-240 V (-15/+10%), 50/60 Hz, 24 watts maximum
Dimensions (Overall):
19.0 inches wide (48.3 cm)
1.72 inches high (4.4 cm)
9.2 inches deep (23.4 cm)
Mounting: one space (1U) in a standard 19-inch rack
Weight: 4.5 pounds (2.1 kg)

Products to compare:
Comparing Products
Your browser currently does not support some features required by this site. Please try another browser