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Additionally, a constant voltage speaker system allows for the use of multiple speakers
on each channel, without the need for complicated impedance calculations and
configurations. In a constant voltage system, all speakers on a given channel are
connected in parallel and the complicated impedance calculations are replaced by a
simple wattage calculation.
For example, if you want to connect two speakers per channel in a traditional 8-ohm
speaker system, you must either connect them in series, which results in an overall 16-
ohm impedance, or in parallel, which results in an overall 4-ohm impedance. In the first
case, the 16-ohms impedance effectively halves the output power of your amplifier,
resulting in 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. 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. For example, with this 120-watt amplifier, the total load from the speakers should
not exceed 96 watts.
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.
Summary of Contents for 18802
Page 18: ...18 Sample Connection Diagram ...
Page 19: ...19 Block Diagram ...
