32-2001.fm Page 9 Friday, February 4, 2000 7:53 AM

Four 8Ω Speakers

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.

If you connect these speakers in paral- lel, the total impedance is 2 ohms (8 ⎟ 4

=2). This falls below the minimum rat- ing.

You can arrive at a proper total imped- ance by combining series and parallel connections.

1.Group speakers into pairs.

2.Connect each pair of speakers in series.

For example, the total impedance of each pair of 8-ohm speakers is 16 ohms (8 + 8 = 16).

3.Connect the pairs of speakers in parallel.

4.To determine the total impedance of speakers connected in serial and parallel combined, divide the imped- ance of one pair of speakers by the number of pairs.

For example, if you want to connect four 8-ohm speakers in serial and parallel combined, divide 16 (the

impedance of one pair of speakers) by 2 (the number of speaker pairs) for a total speaker impedance of 8 ohms.

5.Connect the negative (–) terminals of all pairs of speakers to the ampli- fier’s COM terminal.

6.Connect the positive (+) terminals of all pairs of speakers to the ampli-

fier’s terminal that matches the total speaker impedance (8Ω, in this example).

Multiple Speakers with

Transformers

For complex multiple-speaker arrange- ments that require many speakers and long runs of connecting wire, we recom- mend you use a line transformer (not supplied), available at your local Ra- dioShack store.

Note: When running lengths of wire longer than 50 feet, use wire that is heavier than 16 gauge.

There are several advantages to using transformers.

•You can connect speakers with dif- ferent impedances without causing differences in output between the speakers.

•You can add or remove a speaker without having to recalculate the entire system’s impedance.

•You can reduce signal loss when you use speaker wire over 50 feet long.

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Radio Shack 32-2001, MPA-40, 811081640B owner manual Multiple Speakers with Transformers
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MPA-40, 32-2001, 811081640B specifications

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