OEM IW-303 — Speaker Selector Switch Installation Guide

The IW-303 is a speaker selector switch that lets you route a single amplifier channel to Pair A, Pair B, or both speaker pairs simultaneously. It's available in White, Ivory, and Almond finishes and can be used with zero, one, or two OEM Autoformer Volume Controls depending on how much independent volume control you need per zone.

Wiring Configurations

Using the IW-303 without Volume Control(s)

1. Connect the amplifier's left & right speaker outputs to the terminal block on the IW-303 marked "Input" [C].
2. Connect the left & right wires going to speaker pair "A" to the terminal block marked "Speakers A".
3. Repeat for speaker pair "B" to the terminal block marked "Speakers B".

Using the IW-303 with One (1) Volume Control

Provides combined control over both speaker pairs.

1. Connect the amplifier's left & right speaker outputs to the terminal block marked "Input" on the OEM Autoformer Volume Control.
2. Connect the Autoformer's "Output" terminal block to the IW-303 terminal block marked "Input" [C].
3. Connect speaker pair "A" to the "Speakers A" terminal block, and pair "B" to "Speakers B".

Using the IW-303 with Two (2) Volume Controls

Provides individual volume control over each speaker pair. Suggestion: when using two controls, locate the second volume control in the same room/area as the second pair of speakers.

1. Connect the amplifier's left & right speaker outputs to the IW-303 terminal block marked "Input" [C].
2. From the "Speakers A" terminal block, run wires to the Input of one OEM Autoformer Volume Control; connect that control's "Output" to speaker pair "A".
3. Repeat for speaker pair "B" with a second Autoformer Volume Control.

Wire & Wiring Notes

• Wiring to and from the switch should be CL-2 or CL-3 rated. Use 16 gauge or larger for runs over 100 feet.
• Strip 1/4" off each wire. Ensure all strands are twisted together and inserted into the respective terminals.
• For 12 gauge and larger wire, trim some strands to fit into the terminals.
• Perform initial testing of the selector at low volume to prevent equipment damage.

Important: More Than Two Pairs of Speakers

When speaker pairs A & B are both 8 ohms, the summed impedance when both pairs are playing simultaneously drops to 4 ohms. Because most amplifiers are designed to operate between 4-8 ohms, do not configure your system to play more than two pairs of 8 ohm speakers at a time without an impedance compensating device.

If you need to play more than two pairs of 8 ohm speakers simultaneously, OEM Systems manufactures impedance-compensating speaker switchers:

• SW-4SPKR — 4 pair speaker switcher with impedance compensation
• SW-8SPKR — 8 pair speaker switcher with impedance compensation