Wilson Electronics Alexandria XLF, Owner'S Manual

Page: 26 / 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
• Structures within the listening room.
• The volume of air itself within the listening room.
Structural Resonance
Structural resonances are familiar to most people as buzzes and rattles, but this type
of resonance usually only occurs at extremely high volume levels and is usually masked
by the music. In many wood frame rooms the most common type of structural resonance
problem is “booming” of walls and floors. You can test for these very easily by tapping
the wall with the palm of your hand or stomping on the floor. Most rooms exhibit mid-
bass “boom” when struck. The loudspeaker playing in the room also excites these reso-
nances. To give you an idea of what the perfect wall would sound like, imagine rapping
your hand against the side of a mountain. Structural wall resonances generally occur in
the low to mid-bass frequencies and add a false fullness to the tonal balance. They, too,
are more prominent at louder levels, but their contribution to the sound of the speaker
is more progressive. Rattling windows, picture frames, lamp shades, etc., can generally
be silenced with small pieces of caulk or with blocks of felt. However, short of actually
adding additional layers of sheet rock to flimsy walls, there is little that can be done to
eliminate wall resonances.
Volume Resonance
The physical dimensions and volume of air in a room will also support standing
wave modes and resonances at frequencies determined by the size of that room. Larger
rooms will resonate at a lower frequency and have more complex (better) modal distri-
butions than will smaller rooms. Volume resonances, wall panel resonances, and low
frequency standing waves combine to form a low frequency coloration in the sound. At
its worst, it is a grossly exaggerated fullness, which tends to obscure detail and distort
the natural tonal balance of the speaker system.