CHAPTER 1 Fundamentals of Audio and Acoustics Absolute levels are useful for rating audio equipment. A power amplifier that can produce 100 watts of continuous power is rated at L out 10 log W 10 log 100 20 dBW (1.2) This means that the amplifier can be 20 dB louder than a 1 watt amplifier. A mixer that can output 10 volts prior to clipping can be rated at L out 20 log E 20 log 10 20 dBV (1.3) If the same mixer outputs 1 volt rms at meter zero, then the mixer has 20 dB of peak room above meter zero. If a loudspeaker can produce a sound level at 1 meter of 90 dB ref. 20 Pa (micro-Pascals), then at 10 meters its level will be L p 90 20 log 1 10 90 ( 20 ) 70 dB (1.4)