Installation manual

Community WET II - Operation and Installation Manual - Page 19
SELECTING AMPLIFIERS
Amplifiers are a vital part of the sound system’s performance and should be carefully selected for
appropriate power output. A table is provided below to help you size your amplifier’s power output
capability to the various models in the WET II product line.
Typically, it’s good practice to select an amplifier that can provide substantially more power than the
continuous rating of the loudspeaker. This is so that enough reserve power will be available for transient
peaks. More loudspeakers are damaged by under-powering them than by over-powering.
If you know in advance that a particular loudspeaker, or zone of loudspeakers will never be used at, or near
their maximum rated power, then it’s acceptable to select a power amplifier that is equal to, or slightly
larger than the loudspeaker’s power handling specification. We do not recommend operating WET II
loudspeakers with an amplifier that does not at least meet the rated power handling of each model.
Model Rated Power Handling Recommended Amplifier Power
W2-218 125W RMS / 300W Program 250 - 375 WRMS at 8 Ω
W2-228 250W RMS / 600W Program 500 - 750 WRMS at 4 Ω
W2-2W8 250W RMS / 600W Program 500 - 750 WRMS at 8 Ω
W2-215 200W RMS / 500W Program 400 - 600 WRMS at 8 Ω
W2-312 200W RMS / 500W Program 400 - 600 WRMS at 4 Ω
W2-322L
LF: 400W RMS / 1000W Program
MF/HF: 160W RMS / 400 W
Program
Bi-amped
LF: 800 - 1200 WRMS at 4 Ω
MF/HF: 320 to 640 WRMS at 8 Ω
W2-315 200W RMS / 500W Program 400 – 600 WRMS at 4 Ω
W2-112 200W RMS / 500W Program 400 – 600 WRMS at 8 Ω
W2-122 400W RMS / 1000W Program 800 – 1200 WRMS at 4 Ω
W2-125 400W RMS / 1000W Program 800 – 1200 WRMS at 4 Ω
Note: “WRMS” = “Watts RMS” = “Watts Root Mean Squared”
Amplifiers for 70V/100V Operation
In past times, nearly all 70V/100V amplifiers were of modest power level and employed step-up
transformers to increase their output voltage to a fixed value of 70V (or 100V) at their maximum operating
level. The purpose of stepping up the output voltage is largely to decrease the wire size needed for a given
system, particularly when long wire runs are unavoidable. A basic rule of Ohm’s Law is that the higher the
voltage and the higher the load impedance, the less effect the cable resistance has on the absorption of
power within the cable. A 70V/100V system achieves both of these desirable design goals.
A second important reason for constant voltage systems is that the use of a step-down transformer at each
loudspeaker (or in the case of WET II products… a step-down autoformer) permits the installer to choose
among several power taps at each individual loudspeaker location. This lets the installer adjust each
loudspeaker’s level in relation to the other loudspeakers, even though multiple loudspeakers are driven by
the same amplifier on the same circuit. Without a transformer (or an autoformer), level adjustment could
only be accomplished by adding resistance to one or more loudspeakers. Resistors would in fact reduce the
operating level, but would also consume valuable power from the amplifier, as well as produce unnecessary
heat as a byproduct.