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IQ-INT II IQ Interface

Page 7

Reference Manual

its lower capacitance. When used with the Crown

Bus, a shield serves two purposes: 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

wire like West Penn 452 or equivalent.

• If shielded wire is used, only connect the shield

at the input connection.

Connecting both ends of

the shield may cause a ground loop.

• The total capacitance for each loop should be

40 nanofarads or less.

Add up the loop’s total

capacitance based on the wire’s rating in picofarads

per foot, and allow approximately 60 picofarads for

each connected IQ component. Experience has

shown that loops with 75 or more components

usually require at least one repeater.

• Add an IQ Repeater

for long loops greater than

1,000 feet (305 m) or when required by high-

capacitance wire. Although repeaters are

recommended 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

recommend shielded wire, unshielded wire typically

has less capacitance and can support longer loops.

• Never use the ground wire in a mic snake.

times, it may be convenient to run Crown Bus data

signals to and from stage monitor amplifiers along

unused 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

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 Crown Bus

loop will be shorter than low-capacitance twisted-

pair wire.

Outside RF interference is seldom a problem for a Crown

Bus loop—especially if shielded twisted-pair wire is used.

However, there are extreme situations when fiber optic

wiring is recommended. For example, locating a Crown

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

Crown Bus loops when distances exceed several miles.

Three different of connectors are used for Crown Bus

wiring on IQ components. These include DIN connectors,

RJ45 connectors, and removable barrier strip plugs. The

IQ-INT II

uses 5-pin DINs for input and 4-pin DINs for

output. Figure 3.2 shows how to connect IQ components

with DIN connectors.

Fig. 3.2 IQ-INT II Output Connection to a DIN Input.

Fig. 3.3 IQ-INT II Output Connection to Barrier Block Input.

Fig. 3.4 Barrier Block IQ Component Connection to an

IQ-INT II

1 Input (–)

2 Input (+)

3 GND

4 Not used

5 Not used

DIN IQ Component

Input

Optional Shield

Output (–) 1

Output (+) 2

Not used 3

Not used 4

IQ–INT II Output

OUT IN

+ – + –

Output (+)

Output (–)

Input (+)

Input (–)

GND

Output (–) 1

Output (+) 2

Not used 3

Not used 4

Barrier Block IQ

Component

Input

IQ–INT II Output

ptional Shield

The following examples show how to connect the

IQ-INT II to other IQ components on the Crown Bus: