Crown MPX-6, SMX-6, AMB-5 installation manual Multiloop Advantages, Crown Bus Wiring

IQ Mixer / Multiplexer Hardware Installation

Crown Bus can have the same address. Suppose, for example, an IQ System has two Crown Bus loops as shown in Figure 3.1 and an SMX-6is installed in loop 1 and given IQ address 77. No other SMX-6can be given the same address in Crown Bus loop 1. However, an SMX-6can have the same address if it is installed in loop 2. Different IQ components can have the same address and be in the same Crown Bus loop. In the previous example, an AMB-5could be installed in loop 1 and use IQ address 77 because it is not an SMX-6.

A valid IQ address is any number from 1 to 250. Do not use a number higher than 250 since they are reserved for special use. An address of ÷0š (zero) should not be used. The IQ address is determined by adding the values of each segment of the DIP switch which is turned on (pushed down). Figure 3.5 shows the value of each DIP switch segment. For example, if the desired unit address is 1, only switch 1 should be down. If the desired unit address is 217, switches 8, 7, 5, 4, and 1 should be down (128+64+16+8+1=217). See Appendix A for list of all valid DIP switch settings.

If the IQ interface used is an IQ-INT, the system can have up to eight separate Crown Bus loops. This will enable the audio system to be divided into different zones, each with its own Crown Bus loop. Dividing the IQ System into multiple Crown Bus loops has advantages and disadvantages which are listed be- low:

Multiloop Advantages

•A break in communication in one loop does not affect other loops.

•Over 250 IQ components of the same model can be use in a system.

•The same IQ address can be used more than once (once per loop per model).

Single Loop Advantages

•The IQ System can send and retrieve data faster in a single loop.

•÷Real timeš level display of a greater number of units is possible.

3.2.2 Crown Bus Wiring

The Crown Bus is implemented in IQ mixer/multi- plexers as a 20 milliamp current loop operating at

38.4K baud so that it can function with inexpensive twisted-pair wiring. If fiber optic wiring is required contact Crown Tech. Support or Amcron Tech. Ser-

vices (see page 22) for information on adding the appropriate transceivers.

Here are some guidelines for twisted-pair wiring:

•Use shielded twisted-pair wire at least 26 AWG in size. The wire should be of good qual- ity and should NOT have high capacitance (30 picofarads/foot or less is good). Shielded wire is recommended for situations where interfer- ence is a problem. (West Penn 452 or an equivalent wire works well.) The shield serves two purposes: First, it helps prevent the IQ data signal from transmitting to nearby audio wiring. Second, it helps prevent outside RF from interfering with the data signal. However, in most cases interference is not a problem and, since unshielded wire has lower capaci- tance, it is a better choice.

•If shielded wire is used, connect the shield only to the input connector.

•Add an IQ Repeater for very long loops…greater than 1,000 feet (305 m)…or when required by high-capacitance wire. Al- though we recommend adding a repeater for loops longer than 1,000 feet, it is often pos- sible to go 2,000 feet (610 m) or more. The most significant characteristic of the wire is its capacitance. The lower the capacitance, the longer the loop can be. Unshielded wire typi- cally has less capacitance.

•Never use the ground wire in a mic snake line. It may sometimes be convenient to run Crown Bus data signals to and from stage monitor amplifiers along unused wire pairs 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

Mixer/Multiplexer 1Mixer/Multiplexer 2

1 2 3 4 1 2 3 4

Cable connectors are numbered as they appear from the front.

	PIN	PIN
Input (–)	1	1	Input (–)
Input (+)	2	2	Input (+)
Output (–)	3	3	Output (–)
Output (+)	4	4	Output (+)
GND			GND

Fig. 3.6 Crown Bus Wiring for Removable Barrier Blocks

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