Wilson Electronics Alexandria XLF, Owner'S Manual, Page: 24 / 94

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W i l s o n A u d i o S p e c i a l t i e s
Standing Waves
Another type of reflection phenomenon is “standing waves.” Standing waves cause
the unnatural boosting or accentuation of certain frequencies, typically in the bass, to
be found at certain discreet locations in the room. These locations differ according to
room dimension and size. A room generating severe standing waves creates difficulty in
setup. In these rooms, the speaker will sound radically different as it is moved around.
The effects of standing waves on a loudspeaker’s performance are primarily in the areas
listed.
• Tonal balance
• Resolution of low-level detail
• Soundstaging
Standing waves are more difficult to correct than slap echo because they tend to
occur at a lower frequency. Absorbent materials, such as Illbruck Sonex®, are ineffec-
tive at controlling reflections in the bass region. Moving speakers about slightly in the
room is, for most people, their only control over standing waves. Sometimes a change of
placement of as little as two or three inches can dramatically alter the tonal balance of
a small system.
Fortunately, minor low frequency standing waves are well controlled by positioning
ASC Tube Traps™ in the corners of the room. Very serious low frequency accentuation
usually requires a custom-designed bass trap system.
Low frequency standing waves can be particularly troublesome in rooms construct-
ed of concrete or brick. These materials trap the bass in the room unless it is allowed to
leak out of the room through windows and doors.
In general, placement of the speaker in a corner will excite the maximal number of
standing waves in a room and is to be avoided for most direct radiator, full-range loud-