Radio Shack MPA-50 owner manual Connecting Speakers

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determine if your speakers are connect- ed in series, parallel, or series/parallel combined.

Note: We recommend that you use speakers that are rated the same (for example, all 8-ohm speakers) for all se- ries or parallel connections.

•Speakers are connected in series when the first speaker’s positive ter- minal is connected to the next speaker’s negative terminal. Deter- mine the total impedance of speak- ers connected in series by adding up the individual impedances of all the connected 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.

•Speakers are connected in parallel when all their negative terminals are connected together and all their positive terminals are connected together. For speakers rated the same, find the total impedance of speakers connected in parallel by dividing the impedance of one speaker by the number of speakers.

For example, if you want to connect two 8-ohm speakers in parallel, divide 8 (the impedance of one speaker) by 2 (the number of speak- ers) for a total speaker impedance of 4 ohms.

•If you connect more than two speak- ers using only series or only parallel connections, the total impedance might exceed the amplifier’s maxi-

mum impedance (16 ohms) or fall below its minimum impedance (4 ohms).

For example, if you connect four 8- ohm speakers:

–In series, the total impedance is 32 ohms (8 + 8 + 8 + 8 = 32). This exceeds the maximum rating.

–In parallel, the total impedance is 2 ohms (8 ⎟ 4 = 2). This falls below the minimum rating.

You can arrive at a proper total impedance by combining series and parallel connections.

CONNECTING SPEAKERS

You need speakers and wire (available at your local RadioShack store) to com- plete the connections to your amplifier. Be sure to use 16-gauge wire or heavi- er. (The smaller the gauge number, the heavier the wire.)

Remove about 1 inch of insulation from both ends of each wire. Then twist the exposed wire to secure all its strands.

Connect the speaker wire to the amplifi- er by pressing down on the appropriate push terminal tab and inserting the end of the twisted wire into the terminal’s hole. Then release the tab to secure the wire.

You can connect one or more 4-, 8-, or 16-ohm speakers, with or without trans- formers, between the amplifier’s output and the speakers’ input. To ensure equal volume from each speaker, all the connected speakers should have the same impedance rating.

Speakers 7