Audio and speakers
Crossover frequency
The frequency below which a receiver redirects bass from a speaker to the subwoofer, with 80 Hz as the THX standard for most systems.
A crossover splits the band between speakers and subwoofer. Below the crossover point, bass is filtered out of a speaker's signal and sent to the subwoofer; above it, the speaker carries the sound. Bass management does this for every channel set to 'small'.
Too high, and the subwoofer becomes localizable and voices sound thick; too low, and small speakers strain while the subwoofer misses bass they cannot reproduce cleanly.
THX standardized 80 Hz, which suits most bookshelf and many tower speakers because the ear cannot easily locate sound below that. Set the crossover about 10 to 20 Hz above the speaker's -3 dB point, and set even large towers to small so the subwoofer, placed for bass, handles the bottom octaves.
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