zapco I-Force i-250 User Manual page 33

Even Numbers of speakers can be connected in series parallel
circuits to achieve the correct load for your amplifier.
Example: The above drawing shows four 4-ohm loads. In series you
would have 16 ohms. This high impedance would reduce effective amp
power. In parallel they would create a 1-ohm load, and seriously damage
your amplifier.
Solution: The top pair is wired in series to make an 8-ohm load. The
bottom pair is also wired to 8 ohms. The two 8-ohm loads are then wired in
parallel for a total load of 4 ohms.
Your local Zapco dealer can help you with series parallel circuits to
match your speakers to your amp.
The chart on the following page will give you a quick reference for the
most common combinations.
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