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lower overall volume levels. In the latter case, the 4-ohms impedance means that your
amplifier will have to work harder and must be rated as stable at 4 ohms. Adding a third
speaker to the mix would complicate it further, producing either a 24-ohm or 2.67-ohm
overall impedance. Note that very few amplifiers are stable under 2-ohm loads, so that is
usually not an option.
On the other hand, with a constant voltage system, you consider first the RMS output
wattage of the amplifier. This should be reduced by 20% to compensate for insertion loss.
For example, if using a 100-watt amplifier, the total load from speakers should not exceed
80 watts.
Each individual speaker on a given channel is set to a value such that the total does not
exceed the rated power, less 20%. You do not need to worry about making the total as
close as possible to the limit; just ensure that the total does not exceed the limit.
If all speakers are set to the same wattage value, they will all have the same volume level.
If one speaker is set to a higher wattage value, it will be louder than the others, while a
speaker set to a smaller value will be quieter than the others. This allows you to
compensate for the environment in which the speaker is placed. For example, a speaker
placed outside would need to be louder than a speaker placed in a small room.
SPEAKER WIRING
Most constant voltage speaker installations will consist of
multiple speakers per channel, with all speakers connected in
parallel, as shown in the diagram to the right.
To wire speakers in parallel, connect the first speaker to the
amplifier as normal. Connect the positive terminal on the first
speaker to the positive terminal of the second speaker, and
the negative terminal on the first speaker to the negative
terminal on the second. Repeat for each additional speaker in
the array.
7
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