Community WET Series II, Руководство по эксплуатации и установке

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Community WET Series II - Operation and Installation Manual - Page 18
70.7V and 100V Systems
Several voltage standards have been put in place regarding so called ‘constant voltage systems.’ In the United
States, 25V, 70.7V and 100V are common. Occasionally 140V systems can be found, usually in very large venues
such as racetracks, where the need to overcome cable resistance by scaling the voltage upwards becomes
extremely important, due to the very long cable lengths from the amplifiers to the loudspeakers. In Europe and
Asia, most constant voltage systems use the 100V standard.
A WET Series II loudspeaker equipped with an optional autoformer supports both the 70.7V and 100V
standards. The same physical conductors are used for both voltage standards, but the power level of each tap
is different, depending on whether the voltage is 70.7V or 100V.
A 100V system will produce twice the power at a given tap, as that of a system that is operated at 70.7 volts.
This can be verified by the simple Ohm’s Law calculation E
2
/Z = W, where E is the voltage applied, Z is the load
impedance, and W is the power expressed in Watts. Assuming a load impedance of 50 ohms, we can see that
70.7 x 70.7 / 50 = 99.97 and that 100 x 100 / 50 = 200. Therefore, when scaling up from 70.7V to 100V the
power will double; when scaling down, the power will halve.
CAUTION: Be sure to carefully observe polarity when wiring your loudspeakers. If one loudspeaker is
wired with the opposite polarity from another loudspeaker, acoustic cancellation will occur. The result
will be less power output than if only one loudspeaker were used by itself.