Radio Shack MPA 31 Owner's Manual page 7

For exam|:te, if you plan to connect
two 8-ohm speakers in paraUel, di-
vide 8 (the impedance of one speak-
er) by 2 (the rsjmber of speakers) f a
a total speaker impec^ce of 4
ohms.
COM 4 0 8 0 160 70V
8Q^
an
• If you connect more than two speak-
a s usng only seri^ or only paraBel
comecttons, the total impedance
might exceed the amplifier's maximum
impedance (16 ohnrs) or fafl below its
mininrHjn impedance (4 ohms).
For example, if you connect four 8-
ofvn speakers:
-In series, ttie total impedance is
32 ohms (8 -F 8 -f 8 -F 8 = 32).
This exceeds the maximum rating.
-In paraflel, the total impedance
is 2 ohms (8 divided by 4 = 2).
This fafls bdow the minimum rating.
You can anive at a proper total im-
pedance by combining series and
parallel ccmriections.
Connecting Orriy One
Speaker
Connect the speaker's negative (-) ter-
minal to the amplifier's COM tenrrwial.
Then connect the ^leaker's positive
(-F) terminal to the terminal that match-
es the speaker's impedance (4Q, 8Q,
or 16Q).
isn 70V
Connecting Sg;»aker8 in
Series
Follow these steps to connect speakers
in series.
COM 4 0 8 0 160 70V
8U
1. CannecA the first speaker's positive
(-F) terminal to the second speak-
er's negative (-) termirral.
2. Connect the first speaker's negative
(-) terminal to the amplifier's COM
tenninal.
3. Connect the second speaker's posi-
tive (-F) terminal to the amplifier's
4 Q , 8 Q , or 16 Q temninal that
matches the toal speaker impectence.