QSC Audio IT-42 User Manual

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IT-42 Installation Guide

INTRODUCTION

The IT-42 is an output isolation transformer accessory for the QSC CX 302 amplifier, allowing it to drive two 25-, 70-, and 100-volt distributed lines in stereo or
parallel, or a single 140- or 200-volt line in bridged mono. It mounts conveniently to the back of the amplifier and requires no additional rack space.

In stereo or parallel modes, the two distributed lines may be loaded at up to 400 watts each. In bridged mono, the distributed line may be loaded at up to 800
watts.

Figure 1 shows the necessary mounting and configuration features of the IT-42

1. Mounting tabs

2. Transformer input wires with spade lug connectors

3. Isolated output barrier strip

4. Transformers

5. Slotted mounting tabs (× 2)

6. #8-32 × 5/16” Philips screw, black (× 2),

included

Figure 1

INSTALLATION

Although the IT-42 transformer accessory can be installed while the amplifier is already rack mounted, installation is much easier with the amplifier out of the rack
and placed face-down so it rests on its front panel.

CAUTION: Turn off the amplifier before installing the IT-42 accessory.

1. Open the safety shroud over the amplifier’s output barrier strip. Fully loosen—but do not remove—the two screw terminals at the top and the two at the bottom.

2. Align the spade lug connectors on the transformer input wires with their respective screw terminals and slide them fully onto the screws. Tighten
the screw terminals.

3. Insert the slotted mounting tabs on the right end of the IT-42 into the slots in the amplifier chassis (Figure 2).

4. Align the holes in the mounting tabs on the left end of the IT-42 with the threaded holes in the amplifier chassis. Insert and tighten the
mounting screws.

5. Press the right end of the bracket in to the left so that the slotted tabs lock to the amplifier and will not pull out (Figure 3).

Rack mounting

The IT-42 adds to the depth of the amplifier, so you
must allow more space at the rear of the rack. See
Figure 4. Because of the additional weight of the
transformers, it is important to support the amp at the
back, even in fixed installations. Rear rack ear kits for QSC
amplifiers are available from QSC’s technical services
department or from your dealer or distributor.

If you are using in the same rack two or more
amplifiers with transformer accessories, separate
them by at least one rack space to minimize crosstalk.

CX 302 Amplifier • Amplificateur CX 302 • CX 302-Verstärker • Amplificador CX 302

Figure 4

Figure 2

Figure 3

To front rack rail
Vers le rail montage avant
Zur Vorderrackstange
Hacia la barandilla de

montaje anterior

16.48"

418.6 mm

17.31"

439.7 mm

*TD-000081-00*

TD-000081-00

Preliminary

CONFIGURATION

With the IT-42 installed, the CX 302 amplifier can operate in several different configurations listed below.

TWO-CHANNEL OR TWO-ZONE OPERATION (STEREO OR PARALLEL)

Both channels 25V
Both channels 70V
Both channels 100V
One channel 25V, the other 70V or 100V
One channel 70V, the other 100V

BRIDGED MONO OPERATION

140V or 200V
Amplifier settings: To minimize transformer saturation, we recommend

always

using the amplifier’s 75 Hz input filters. We also
recommend using the clip limiters in most applications. See the amplifier user’s manual for instructions on configuring filters and
clip limiters, as well as configuring the CX 302 for stereo, parallel, or bridged mono operation.

Connecting outputs

Turn off the amplifier before opening the safety shroud over the output barrier strip or making any changes to the output
connections. Always close the safety shroud when you finish working on the output connections and before turning the amplifier
on. The illustrations at right will help you identify the correct output terminals for your distributed line.

Use fully insulated wiring that conforms with local and national electrical and safety codes. Wiring for circuit classes listed below
are as specified by the 1999 National Electrical Code, which is prevalent in the United States. Codes in your location may vary.

25-VOLT LINE
Connect the 25-volt distributed line across the 70V and 100V terminals. Use wiring suitable for a Class 2 circuit.

70-VOLT LINE
Connect the 70-volt distributed line across the COM and 70V terminals. Use wiring suitable for a Class 2 circuit.

100-VOLT LINE
Connect the 100-volt distributed line across the COM and 100V terminals. Use wiring suitable for a Class 2 circuit.

140-VOLT LINE (BRIDGED MONO)
Connect a jumper wire between the COM terminals of Channel 1 and Channel 2. Connect the 140-volt distributed line across the

70V terminals of Channel 1 and Channel 2. Use wiring suitable for a Class 3 circuit.
200-VOLT LINE (BRIDGED MONO)

Connect a jumper wire between the COM terminals of Channel 1 and Channel 2. Connect the 200-volt distributed line across the
100V terminals of Channel 1 and Channel 2. Use wiring suitable for a Class 3 circuit.

COM

70V

100V

COM

70V

100V

COM

70V

100V

COM

70V
100V
100V

70V

COM

COM

70V
100V
100V

70V

COM

25V line

70V line

100V line

140V line

200V line

SCHEMATIC

Ch. 1 + out

Ch. 1 - out

Ch. 2 + out

Ch. 2 - out

Phone: [phone] Fax: [phone] Technical Services phone: [phone] Technical Services fax: [phone]

100V
70V

COM

100V
70V

COM

QSC Audio Products, Inc. 1675 MacArthur Blvd., Costa Mesa, California 92626 USA

www.qscaudio.com