Subwoofers - Dynaudio AIR 15 Reference Manual

Appendix: Acoustics

Subwoofers

A subwoofer is a monitor that reproduces low frequen-
cies. The purpose is to take over from the main mon-
itor(s) as frequencies approach the lower end of the
frequency range – approximately below 120 Hz. For
professional monitor systems, it is commonly preferred
to use subwoofers below approximately 80 Hz – but of
course, the best solution depends on the performance
of the main monitors.
The low frequency contents of just one or all the main
channels can be directed to one subwoofer.
Psychoacoustics tells us that there is no directional in-
formation in audio signals below approximately 120 Hz.
Accordingly, a subwoofer should be placed in a position
where the best distribution is achieved. However, it is
very important to reduce subwoofer distortion to an ab-
solute minimum, because distortion will add harmonics
(2, 3, 4 etc. times the frequency reproduced). Especially
the third harmonic may dominate the signal. Reproduc-
ing a frequency of 100 Hz can result in the generation
of an audible frequency component at 300 Hz, which
presents directional information to the human hearing
system.
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