Radio Shack MPA-125 - Manual (Page 12)

12 Connections
Follow these steps to connect speakers using a transformer.
Connect a wire from 70V RMS on the back of
the amplifier to the transformer’s desired pri-
mary tap (10, 5, 2.5, 1.25 or 0.62 watts).
Note: Usually, each speaker in a system
uses the same wattage tap. If you want a
particular speaker to have a higher volume
level, connect the wire from
70V RMS to a
higher wattage tap on the transformer.
Connect a wire from COM on the back of the
amplifier to the C (common) taps on the
transformer’s primary side.
Connect a wire from the speaker’s positive
(+) terminal to the transformer’s secondary
tap that matches the speaker’s total imped-
ance (4 ohms, 8 ohms, or 16 ohms).
Connect a wire from the speaker’s negative
(–) terminal to the
C (common) tap on the
transformer’s secondary side.
CONNECTING POWER
To connect the amplifier to power, plug its
power cord into a standard AC outlet.
Your amplifier’s fuse (located on the amplifi-
er’s back panel) protects the amplifier from
voltage surges. If the PROTECTION indica-
tor does not light when you press
POWER
(see “Using Your Amplifier” and “Safety Indi-
cators” on Page 13), check the fuse. If it is
blown, see “Replacing the Fuse” on Page 17.
USING YOUR AMPLIFIER
Press in POWER to turn on the amplifier.
Start the input sound source.
Rotate MASTER VOLUME to its mid-position.
One at a time, adjust MIC 1 , MIC 2 , MIC 3 , MIC
4/PHONO , and CD/AUX to the desired volume
and balance.
Note: If you hear feedback after you adjust
these controls, turn
FEEDBACK FILTER clock-
wise until the noise disappears (see “Using
the Feedback Filter” on Page 14).
After you get the desired balance, adjust
MASTER VOLUME to the desired volume lev-
el.
32-2003.fm Page 12 Tuesday, March 28, 2000 10:45 AM