Datasheet

Model 47A Specifications
General Audio:
Frequency Response: ±2 dB 100 Hz to 8 kHz
Distortion (THD+N): <0.5%, measured at 1 kHz, 4-wire input to
2-wire interface pin 2
Signal-to-Noise Ratio: >55 dB, measured at 1 kHz, 4-wire input to
2-wire interface pin 2
Connectors:
Inputs from 4-Wire: 3-pin female XLR
Outputs to 4-Wire: 3-pin male XLR
2-Wire Party-Line Intercom: 3-pin male XLR
Remote Control: 10-pin header, requires user-provided 10-pin ribbon
connector assembly
AC Mains: 3-blade, IEC 320 C14 (mates with IEC 320 C13)
2-Wire Party-Line Intercom Interfaces:
2
Type: 2-channel party-line (PL), unbalanced (pin 1 common;
pin 2 channel 1 audio or DC with channel 1 audio; pin 3 channel 2
audio or DC with channel 2 audio)
Compatibility: single- and 2-channel intercom systems such as from
RTS® and Clear-Com®
Impedance, External Power Mode: >10 k ohms
Impedance, Internal Power Mode: 200 ohms
Nominal Level: –10 or –14 dBu, selectable
“Mic Kill” Signal: square wave, 24 kHz, ±1%
2-Wire Party-Line Power Sources:
4, 2 per interface
Rating: 30 volts DC nominal, 315 mA maximum, software monitored
and controlled
Hybrids: 4, 2 per interface
Topology: 3-section analog circuitry compensates for resistive,
inductive, and capacitive 2-wire party-line loads
Nulling Method: automatic upon user initiation, processor
implements digital control of analog circuitry; null settings stored
in non-volatile memory
Nulling Line Impedance Range: 120-350 ohms
Nulling Cable Length Range: 0-3500 feet, typical
Trans-Hybrid Loss: >40 dB, typical at 800 Hz
4-Wire Inputs: 4, 2 per interface
Type: transformer-coupled, capacitor isolated
Impedance: 13 k ohms
Nominal Level: 0, +4, +6, or +8 dBu, selectable in tandem with
nominal output level
Maximum Level: +22 dBu
4-Wire Outputs:
4, 2 per interface
Type: transformer-coupled, capacitor isolated
Impedance: 50 ohms nominal
Nominal Level: 0, +4, +6, or +8 dBu, selectable in tandem with
nominal input level
Maximum Level: +20 dBu into 2 k ohms
Meters: 8
Function: displays level of 4-wire inputs and outputs
Type: 5-segment LED, modified VU ballistics
Remote Control Inputs:
3
Type: optically coupled
Input: 3-32 volts DC; 2 mA minimum for operation, 20 mA maximum
Functions: auto null interface 1, auto null interface 2, and “mic kill”
AC Mains Requirement:
100-240 volts (–15/+10%), 50/60 Hz,
60 watts maximum
Dimensions (Overall):
19.0 inches wide (48.3 cm)
1.72 inches high (4.4 cm)
8.4 inches deep (21.3 cm)
Mounting: one space (1U) in a standard 19-inch rack
Weight:
4.7 pounds (2.1 kg)
Specifications subject to change without notice.
© by Studio Technologies, Inc.
, September 2014
Studio Technologies, Inc.
Skokie, Illinois USA [phone] www.studio-tech.com
time can be better spent elsewhere!) The need to adjust trim
potentiometers, fabricate special cabling and connector straps,
use nulling earpieces, etc., had to be eliminated. For example,
in virtually all instances, input and output levels fall within just a
few dB of their nominal values and, as such, could be supported
with a limited number of configurable choices. In addition, it was
acknowledged that in this application analog audio circuitry was
capable of providing excellent audio performance, but that the
required manual nulling process was operationally taxing. By
adding digital control to the analog circuitry, automatic nulling
could be performed—the best of both worlds!
The next step was to identify resources that would improve
the installation process and make operation more reliable.
This led to the inclusion of multiple LED level meters, allowing
continuous monitoring of the input and output signals. It also
turned out that in many applications only a small number of user
devices, such as beltpacks, are typically connected to 2-wire
party-line intercom circuits. But power on both pins 2 and 3 of
each interface was necessary for compatibility with SAP panel
applications. By adding two DC power sources to each of the
Model 47A’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 1U enclosure. Us
-
ing standard 3-pin XLR audio connectors would enable rapid
installation and troubleshooting. And by making the Model
47A “universally” powered, installation in any locale could be
directly supported
Studio Technologies, Inc. 50118-0914, Issue 1