Wilson Audio WATCH Dog Subwoofer Series-2 - Manual (Page 18)

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interrupted by curtains or drapes. Slap echo can be controlled entirely by the applica-
tion of absorptive materials to hard surfaces, such as:
• Sonex
• Airduct board
• Cork panels
• Large ceiling to floor drapes
• Carpeting to wall surfaces
In many domestic listening environments, heavy stuffed furnishings are the pri-
mary structural control to slap echo. Unfortunately, their effectiveness is not pre-
dictable. Diffusers are sometimes also used to very good subjective effect, particularly
in quite large rooms. Sound absorbent materials such as described above will alter the
tonal characteristic of the room by making it sound “duller,” much heavier in the bass,
less “bright and alive,” and “quieter.” These changes usually make the room more
pleasant for conversation, but sometimes render it too dull in the high frequencies to
be musically involving. Diffusers, on the other hand, tend not to change the high fre-
quency tonal balance characteristic of the room, but make the sound more “open.” A
combination of absorptive and diffusive treatments is usually the best approach.
Standing Waves
Another type of reflection phenomenon is standing waves. Standing waves
cause the unnatural boosting of certain frequencies, typically in the bass, at certain
discreet locations in the room. A room generating severe standing waves will tend to
make a loudspeaker sound one way when placed in one location and entirely different
when placed in another. The effects of standing waves on a loudspeaker’s perform-
ance are primarily, as follows:
• Tonal balance - bass too heavy
• Low-level detail - masked by long reverberation time - low fre-
quency standing waves