Audioplex AT-12 Installation Manual

Your AT-12 speaker selector uses high-powered transformers with selectable taps which allow you to obtain maximum
power transfer while maintaining a safe load of 4 Ohms or higher on the driving amplifier, regardless of the number of
speakers in use at the time. A six position rotary switch is provided to allow convenient choice of the appropriate tap. Note
that there is no significant power loss with transformer matching, when optimally set there will be a level drop but the full
amplifier power output will be available, divided equally among the speakers in operation.
This system is capable of transforming a 1/3 Ohm load to appear as a 4 Ohm to the amplifier, which is equivalent to 12-4
Ohm or 24-8 Ohm speakers operating simultaneously. Thus it is apparent that many more speakers can be used than the
number of ON-OFF switchers (12) suggest. Some switches can be used to control individual speaker pairs, while perhaps
others may be used to control "zones" consisting of several pairs on the same switch.
These transformers are rated for continuous operation at 100 Watts RMS (300 Watts audio). They are connected so that
the left and right channels are completely isolated electrically. Wiring to the switchbox is through push-to-connect terminals
on the AT-12 rear panel, which can accommodate wire up to 12 gauge, adequate for most installations.
A built-in self powered, minimum impedance load warning indicator is provided to aid in choosing the best matching
setting of the rotary switch. A red and green indicator on the front panel shows a constant indication of operating status. The
amplifier load is 4 Ohms or higher when the green lamp is lit, below 4 Ohms if the red on. If red, simply rotate the load
switch until the indication turns green, and you are operating within a safe parameters.
This indicator system is useful for maintaining maximum power transfer to the speakers in use. If this is desired, rotate
the matching control clockwise until the red lamp comes on, then back off one position at a time until the green lamp lights.
You will then be matched as closely as safely possible to 4 Ohms at the amplifier output, which is the point of maximum
power transfer for the speakers in operation.
A separate label strip is furnished which has a peel-off adhesive back. It can be affixed to any convenient surface, or kept
loose where it will be a convenient reference during the installation process.
Three connector strips are provided with the AT-12. They are removable, so can be wired while connected to the AT-12,
or disconnected and pre-wired to be plugged in later, when completing the installation. This normally is the preferred method
since it is much more convenient.
Viewing the AT-12 from the front, the connection order is Left to Right in groups of 4, with terminal 48 being the #1
speaker set R+, #47 #1 R-, #46 #1 L+, and #45 #1 L-. This sequence repeats for the entire set of connectors, including the
INPUT FROM AMPLIFIER on which is separate.
Connect the AT-12 terminal strip marked "INPUT" to the amplifier output, observing polarity and proper channel
identification (note that the INPUT connector block is green and the OUTPUT connector blocks are black). Strip about 1/4"
of insulation from the wire ends, twist any loose strands together tightly, insert in the appropriate connector opening and
tighten the associated screw down. Make sure no loose strands are hanging out to be a potential cause of a short circuit.
INSTALLATION MANUAL
TECHNOLOGY
IN-WALL TWELVE SPEAKER PAIR SELECTOR
INSTALLATION:
AT-12
2000 - 6/20/00