Ifb circuits – Studio Technologies 42A 2008 User Manual
Page 10
Issue 1, February 2008
Model 42A User Guide
Page 10
Studio Technologies, Inc.
shield pins. With unbalanced sources,
connect signal high to the + pins and
shield to both the – and the shield pins.
If connecting to an unbalanced source in
this manner results in hum or noise, try
connecting signal high to the + pins and
shield to the – pins; leave the shield pins
unterminated.
As previously mentioned, the Model 42A is
compatible with matrix intercom systems
from Riedel. Appendix A, located near the
end of this user guide, provides detailed
connection information.
IFB Circuits
The Model 42A’s four IFB output circuits
each supply DC power and two channels
of unbalanced audio. The IFB circuits are
designed to connect, by way of 3-pin male
XLR-type connectors, to a variety of user
devices that conform to the broadcast
IFB standard. In this implementation pin
1 is used for a combination of shield, DC
power return, and audio common; pin 2
supplies a combination of DC power and
one channel of unbalanced audio; pin 3
supplies a second channel of unbalanced
audio. The DC power supplied on pin 2 is
30 volts nominal with a maximum current
of nominally 200 milliamperes. The audio
superimposed on the DC power has a
nominal signal level of –10 dBu. Its audio
source is the channel one audio input as-
sociated with that specific IFB circuit. The
audio on pin 3 also has a nominal signal
level of –10 dBu. Its audio source is the
channel two audio input channel associ-
ated with that specific IFB circuit.
For convenience, the Model 42A’s four
IFB circuits can be connected by way of
eight 3-pin male XLR-type connectors;
four which are located on the back panel
Signal
Signal
Connections
High (+)
Low (–)
Shield
IFB Circuit 1-Channel 1
24
12
25
IFB Circuit 1-Channel 2
10
23
11
IFB Circuit 2-Channel 1
21
9
22
IFB Circuit 2-Channel 2
7
20
8
IFB Circuit 3-Channel 1
18
6
19
IFB Circuit 3-Channel 2
4
17
5
IFB Circuit 4-Channel 1
15
3
16
IFB Circuit 4-Channel 2
1
14
2
Notes: 1) Connector type on Model 42A is 25-pin
D-subminiature female. Installer must provide plug
(male). Connector uses 4-40 threaded inserts for
locking with mating plug.
2) Wiring scheme follows TASCAM DA-88 convention.
Standard DA-88-style wiring harnesses are directly
compatible, with the exception of 4-40 screw threads
being
required.
Figure 3. Connections for Audio Inputs using
Dual-Channel Nomenclature
Signal
Signal
Connections
High (+)
Low (–)
Shield
IFB Circuit 1-Interrupt
24
12
25
IFB Circuit 1-Program
10
23
11
IFB Circuit 2-Interrupt
21
9
22
IFB Circuit 2-Program
7
20
8
IFB Circuit 3-Interrupt
18
6
19
IFB Circuit 3-Program
4
17
5
IFB Circuit 4-Interrupt
15
3
16
IFB Circuit 4-Program
1
14
2
Notes: 1) Connector type on Model 42A is 25-pin
D-subminiature female. Installer must provide plug
(male). Connector uses 4-40 threaded inserts for
locking with mating plug.
2) Wiring scheme follows TASCAM DA-88 convention.
Standard DA-88-style wiring harnesses are directly
compatible, with the exception of 4-40 screw threads
being
required.
Figure 2. Connections for Audio Inputs using
IFB Nomenclature