Radio Shack MPA-50 - Manual (Page 8)

8 Speakers
One Speaker
Connect the speaker’s negative (–) ter-
minal to the amplifier’s
COM (common)
terminal. Then connect the speaker’s
positive (+) terminal to the amplifier’s
terminal that matches the speaker’s im-
pedance. For example, if you have an 8-
ohm speaker, connect the speaker’s
positive terminal to the amplifier’s 8-ohm
terminal.
Two or More Speakers Without
Transformers
We recommend connections without
transformers if the length of the connect-
ing wires between the amplifier and the
speakers is 50 feet or less.
When making connections without
transformers, all the speakers must
have the same impedance rating to en-
sure equal volume from each speaker.
When there is more than one speaker in
a sound system, you must determine the
total impedance of the speakers before
you can make the correct connection.
The total impedance of all the speakers
must match one of the amplifier’s output
terminals (
4
Ω Ω Ω Ω , 8
Ω Ω Ω Ω , or 16
Ω Ω Ω Ω ).
Speakers in Series
1. To determine the total impedance of
speakers connected in series, add
the impedance of all the speakers.
For example, if you want to connect
two 8-ohm speakers in series, add 8
(the impedance of one speaker)
plus 8 (the impedance of the other
speaker) for a total speaker imped-
ance of 16 ohms.
2. Connect the first speaker’s positive
(+) terminal to the second speaker’s
negative (–) terminal.
3. Connect the first speaker’s nega-
tive (–) terminal to the amplifier’s
COM terminal.
4. Connect the second speaker’s posi-
tive (+) terminal to the amplifier’s
terminal that matches the total
speaker impedance (
16
Ω Ω Ω Ω , in this
example).
8
Ω Ω Ω Ω
Speaker
Two 8
Ω Ω Ω Ω
Speakers
32-2002.fm Page 8 Friday, February 11, 2000 11:36 AM