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Again, it’s only necessary to reduce the reflectiveness of one of the surfaces in each pair of surfaces to
eliminate flutter echo. Since this is concerning the high frequencies, any soft material is appropriate.
Drapery or fabric wall hangings are quite effective on the walls. Bookshelves also work well by
breaking up the flat surfaces. Carpeting should eliminate potential problems between the floor and
ceiling.
Additionally, it is desirable to maintain a degree of left/right symmetry in the room to preserve a
balanced acoustic “space”. For example, if your listening room has full length draperies along the
right wall, and the left wall is bare, slap echo will not be a problem. Nonetheless, the sound stage may
be somewhat distorted, and it could be beneficial to place a fabric or tapestry on the wall opposite the
draperies.
Improve bass in your system
It is widely known that speaker placement relative to the floor and walls can affect the relative amount of bass
that the system produces. Similar to the way that mirror reflects the light of a light source, so can the surfaces
near the loudspeaker reflect the sound waves back into the listening room. However, when the path length
difference of the reflected wave is short relative to the wavelength of the sound, the reflected wave is
substantially in-phase with the original wave. When such conditions are met, the coupling coefficient between
the speaker diaphragm and the air increases, and the speaker efficiency increases. This changes the actual
frequency response of the speaker, and is not attributable to standing waves or other room resonances.
There are typically three reflective surfaces near each speaker: the floor, the rear wall, and the side wall. Each of
these surfaces produces its own reflections, and hence its own cancellation and reinforcement. By properly
selecting the distances to each surface, we can provide a uniform and extended bass response. Conversely,
improper placement of the loudspeakers can result in uneven frequency response and lower bass quality.
In order to take full advantage of the room to provide the most uniform and extended bass response,
it is recommended that the loudspeaker be placed between three (3) and six (6) feet from side walls,
less than one (1) feet from the rear wall, and at least (6) to (12) feet from the opposite wall – more room
length is better to allow long wavelengths (low frequencies) to “unfold.” The measurements are made
from the wall to center of the speaker cone. The exact distances are not critical, although the two
distances should not be within about 33% of each other. A good rule of thumb is that the distance to
the side wall is about 25% (or less) of the room width, and the distance from speaker to speaker is
about 50% (or more) of room width.
