Crown Audio IQ-INT3 - Manual (Page 9)

Page 9
IQ-INT 3 IQ Interface
IQ-INT 3 Reference Manual
• Use twisted-pair wire at least 26 AWG in size.
Use twisted-pair wire with a shield when interfer-
ence is a concern. The wire should be of good
quality and should have low capacitance (30 pi-
cofarads/foot or less). In most cases, interference
is not a problem and unshielded wire is a better
choice because of its lower capacitance. When
used with the IQ Bus, a shield serves two pur-
poses: it helps prevent data signals from being
transmitted to nearby audio wiring, and helps
prevent high external RF levels from interfering
with data transmissions. If you must install
shielded wire, use a low-capacitance shielded
data wire.
• The total capacitance for each loop should be
30 nanofarads or less. Add up the loop’s total
capacitance based on the wire’s rating in picofar-
ads per foot, and allow approximately 60 picofar-
ads for each connected IQ component.
Experience has shown that loops with 50 or more
components usually require at least one re-
peater.
added to the audio lines. Use only the signal lines
which normally connect to pins 2 and 3 of the
XLR’s. Note: Because typical mic cables have
higher capacitance, the maximum possible IQ
Bus loop will be shorter than low-capacitance
twisted-pair wire.
Outside RF interference is seldom a problem for an IQ
Bus loop—especially if shielded twisted-pair wire is
used. However, there are extreme situations when fiber
optic wiring is recommended. For example, locating
an IQ Bus loop next to an AM radio transmission line
may require fiber optic transceivers and cabling. It
may also be more practical to use fiber optics for
extremely long IQ Bus loops when distances exceed
several miles.
Three different types of connectors are used for IQ Bus
wiring on IQ components. These include RJ-45 connec-
tors, DIN connectors and removable terminal block con-
nectors. The IQ-INT 3 uses RJ-45 connectors that
accept standard RJ-45 plugs like the one shown in
Figure 3.2, allowing the use of industry-standard
straight-thru type network cables for input and output
wiring.
Figure 3.4 RJ-45 Output to Din Input
Figure 3.3 RJ-45 Output to RJ-45 Input
Figure 3.2 RJ-45 Plug
Figures 3.3 through 3.7 show how to connect IQ com-
ponents the IQ Bus inputs and outputs.
• Add an IQ Repeater for long loops greater than
1,000 feet (305 m) or when required by high-ca-
pacitance wire. Although repeaters are recom-
mended for loops longer than 1,000 feet, it is often
possible to set up reliable loops of 2,000 feet (610
m) or more without a repeater. Although we recom-
mend shielded wire, unshielded wire typically has
less capacitance and can support longer loops.
• Never use the ground wire in a mic snake. At
times, it may be convenient to run IQ Bus data sig-
nals to and from stage monitor amplifiers along un-
used wires in a mic snake. If this is done, do not
use the ground wire which is normally connected
to pin 1 on an XLR connector, or data noise will be