Ifb circuits – Studio Technologies 41 2007 User Manual

Page 10

Issue 2, February 2007

Model 41 User Guide

Page 10

Studio Technologies, Inc.

connector’s hold-down screws use 4-40
threads. This complies with the original
design standard for D-subminiature con-
nectors which used English rather than
metric thread pitch.

The Model 41’s audio input circuits have
a nominal signal level of +4 dBu. They
are transformer coupled, have a nominal
impedance of 10 k ohms, and compatible
with balanced or unbalanced sources.
Balanced sources should be wired so that
signal high is connected to the + pins,
signal low to the – pins, and shield to the
shield pins. With unbalanced sources,
connect signal high to the + pins, and
shield to both the – and the shield pins.
If connecting 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 41 is
compatible with matrix intercom systems
from Riedel. Appendix A, located near the
end of this user guide, provides detailed
connection information.

IFB Circuits

As mentioned previously, the Model 41
has four independent IFB output circuits
each supplying DC power and two chan-
nels of unbalanced audio. The IFB circuits
are designed to connect to a variety of
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.

The Model 41’s IFB circuits are interfaced
using four 3-pin male XLR-type connec-
tors which are located on the unit’s back
panel. The associated interface cables,
one for each IFB circuit, must be terminat-
ed with 3-pin female XLR-type connectors.
In most cases the IFB circuits should be
wired by way of an input/output connector
panel rather than directly to the external
devices. It’s also recommended that the
panel have “mults” (multiple connectors)

Signal

Connections

High (+)

Low (–)

Shield

IFB Circuit 1-Channel 1

IFB Circuit 1-Channel 2

IFB Circuit 2-Channel 1

IFB Circuit 2-Channel 2

IFB Circuit 3-Channel 1

IFB Circuit 3-Channel 2

IFB Circuit 4-Channel 1

IFB Circuit 4-Channel 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.

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