OEM Systems SW-4SPKR — Impedance Compensating Speaker Selector Manual

The SW-4SPKR is an impedance-compensating speaker selector from OEM Systems Co., designed as a distribution and switching center that allows up to 4 pairs of 8-ohm speakers to be connected to a single stereo amplifier or receiver, with amplifier protection built in.

Overview

Buttons 1 through 4 turn each individual pair of speakers ON and OFF. To maintain individual volume control over each pair, an "Autoformer"-type impedance matching volume control should be installed in-line between the SW-4SPKR and each speaker pair (one control per pair).

Safety & Wiring Notes

• Speaker wiring should be a minimum of 18-gauge; use "CL"-rated wire if running through walls; use 14-gauge wire for runs over 100 feet.
• If uncertain about proper setup and installation, refer to a qualified technician — improper installation can severely damage the device and connected equipment.
• Maintain polarity on all connections: always connect Positive (+) to Positive and Negative (-) to Negative. Never cross wire connections, or a loss of fidelity will occur.
• Amplifier Protection switch: engage this switch whenever two or more pairs of speakers are selected. It protects the amplifier by buffering its output through high-power resistors. If you notice an unusual drop in volume from one speaker or excessive heat from the selector, check the system for possible configuration issues.

Setting Volume Levels (Single Amplifier, Multiple Rooms)

When distributing audio from a single amplifier/receiver to multiple rooms, set the maximum speaker level at the amplifier, not at each room's volume control:

1. Set each room's individual volume control to its maximum position
2. Adjust the amplifier to the highest normal listening level you'd want in any room
3. Turn down the volume at each room's individual volume control as desired
4. If a volume control vibrates in the wall, or sound can be heard from the control when turned down, the amplifier level is set too high — reduce it, or damage may occur to the volume controls and/or amplifier

Note: if a speaker's volume control is turned off, it cannot be turned back on from the speaker selector — the two controls are independent of each other.

Specifications

Wiring & Connection

Connect each pair of speakers to the appropriate screw terminals: 1L+/1L-/1R+/1R- for Speaker Pair 1, and correspondingly for Pairs 2, 3, and 4. Connect the amplifier output to the input of the speaker selector, taking care to maintain proper polarity on all connections. In a typical 4-room installation, each room gets its own speaker pair (1-4), optionally with its own impedance-matching volume control for independent level adjustment.

Manufactured by OEM Systems Co.