Originally Posted by Heinrich S
So is music and home theater sound made up of sine waves at different frequencies? Test bench uses sine waves.. correct?
Music is made up of many sine waves at many different frequencies, each with a unique envelope or time-versus-amplitude characteristic, all mixed together. The magic word is multitone.
In a typical musical track thousands of different frequencies are present. Some are harmonically related but many are either near misses of harmonics or aren't harmonics of any other tone at all.
Test bench tests for amplifiers are generally done with one pure tone or two pure tones or a pure tone whose frequency is steadily varied across the audio band over a period of a few seconds. Audyssey users are familiar with swept tones or chirps.
Multitones necessarily have high crest factors, but single pure tones whether steady or swept have low crest factors.
One exception to the rule I just gave about multitones and crest factors is pure square waves which contain odd harmonics with carefully defined amplitudes and phase, and have a very low crest factor of 0.0 dB. Pure sine waves have a crest factor of 3.0 dB. The crest factor of music varies from as low as 8 dB to more than 30 dB with 17-20 dB being a very high number.
The classic "boat anchor" high mass power amplifier is generally designed to handle signals with a very low crest factor. If you are running a shaker table, its probably exactly what you want. ;-)Edited by arnyk - 7/24/13 at 7:56am