Radio Shack 32-2054, User Manual, Page: 7 / 11

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Connecting Four Speakers in Series and Parallel Combination
1. Group the four speakers into two pairs (A and B, C and D). Connect each
pair of speakers in series: A’s positive terminal to B’s negative terminal, C’s
negative terminal to D’s positive terminal.
If you use all 8
Ÿ speakers, the total impedance of a pair is 16 Ÿ .
2. Connect the two pairs together in parallel: A’s negative terminal to D’s
negative terminal, B’s positive terminal to C’s positive terminal.
If you use all 8
Ÿ speakers, the total impedance of the four speakers thus
connected is 8 Ÿ ((8+8)/2=8).
3. Connect the negative terminals of Speakers A and D to the amplifier’s
COM terminal, and the positive terminals of Speakers B and C to the
amplifier’s 4
Ÿ
, 8
Ÿ
, or 16
Ÿ
terminal.
Speaker A
Speaker B
Speaker D
Speaker C
Amplifier Terminals
Connecting Speakers with Transformers
For best results when using two or more speakers, connect a line transformer
(not included) to each speaker. Transformers allow you to:
• Connect speakers with different impedances without causing output
differences between the speakers.
• Add or remove a speaker from the PA system without having to recalculate
the entire system’s impedance.
• Reduce signal loss when using a speaker wire over 50 feet (15.24 meters)
long.
Line transformers have primary connection taps on the input side, which are
rated in watts, and secondary connection taps on the output side, which are
rated in ohms. Before you connect speakers, be sure the total wattage of the
primary taps you use does not exceed the amplifier’s maximum output power
rating (40W).
The following illustration shows how to connect three speakers with
transformers.
• Connect the amplifier’s
70V terminal to the primary taps (10, 5, 2.5, 1.25, or
0.62 watts) of the transformer.
• Connect the amplifier’s COM terminal to the C (common) taps on the Input
Side of the transformer.
• Connect the speaker’s positive terminal to the transformer’s 4 Ÿ , 8 Ÿ , or 16 Ÿ
tap (whichever matches the total speaker impedance).
• Connect the speaker’s negative terminal to the C tap on the Output Side
of the transformer.
Notes:
• Do not connect multiple wires to the amplifier’s 70V and COM terminals.
• Wires with the mark
A
are to be connected together.
• Usually, a speaker in a system uses the same wattage tap of its transformer.
If you want a particular speaker to have a higher volume level, connect
the wire from the amplifier’s
70V terminal to a higher wattage tap on the
transformer.
Illustration on Page 14
Connections
Connections