现场扩声

rate 额定  according to 取决于，根据   capability能力　amplifiers 功率放大器
sine wave 正弦波 stated规定的  loadimpedance.负载
crest factor 峰值系数　square wave has a crest factor equal to unity 方波的峰值系数为１．
(peak-to-RMS ratio)峰值与均方根值或有效值之比
square wave 方波
spech signals语言信号
  amplifier's power 功率的功率　　nominal标称 rating额定
peak output voltage 峰值输出电压 primarily 　主要的，根本的，
all amplifiers are rated according to their maximun sine wave output capability into a stated loadimpedance.所有的功放的额定功率取决于给定一个规定的负载，所能输出最大正弦波的能力．
since music and spech signals are composed primarily of sine-like waves因为音乐和语音信号主要由各种正弦波复合而成，
the amplifier's power nominal rating is stated as 0.707,the actual peak output voltage rating of the amplifier,or 3dB lower.功放标称的额定功率是（规定所能输出）最大正弦波电压时的０．707(√2⁄2)倍.或更低.这时输出的峰值电压已达到功放的额定值.

why then do we rate this amplifiers at only 100 watts?
为何我们仅仅规定功率放大器的功率为100W？
all amplifiers are rated according to their maximun sine wave output capability into a stated loadimpedance.所有的功放的额定功率取决于给定一个规定的负载，所能输出最大（不失真的）正弦波的能力．the sine wave has a 3dB crest factor (peak-to-RMS ratio),while the square wave has a crest factor equal to unity .正弦波有3dB的峰值系数，而方波的峰值系数为0dB。
since music and spech signals are composed primarily of sine-like waves因为音乐和语音信号主要由各种正弦波复合而成，
the amplifier's power nominal rating is stated as 0.707,the actual peak output voltage rating of the amplifier,or 3dB lower.功放标称的额定功率是输出最大正弦波（不失真的）电压时的０．707(√2⁄2)倍或更低.这时功放所输出的峰值电压已达到功放的额定值.

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厉害!!!!!!!!!!!!!!!!