Avalon Acoustics Sentinel - Manual (Page 53)

53
Early Reflections
When arranging the furnishings in your listening room, remember that
reflective objects should not be within a five foot radius of either the speaker
or listener to avoid early reflections. This suggests the possibility of a
dual-purpose room, with one end devoted to music reproduction, and the
other end for another use, such as a study or office. In this way, the area
behind the listener will contain items that will reduce problems with standing
waves and/or flutter echo, while the zone around the speakers remains
relatively free from reflective objects.
If you wish to achieve an even more spacious sound-stage, it may be useful
to place a sonically absorbent material on the side and rear walls near the
speakers. This can be particularly effective at the points where the sound
wave is directly reflected to the listening position (a mirror can be used to
determine these points, as illustrated in Fig. 9.2). As the distance to the wall
becomes smaller, the suppression of these reflections becomes more
important.
In order to enhance the sound stage depth (and hence the feeling of musical
involvement), it is important to have a greater distance from the speakers to
the rear wall than to the sides walls. This is generally easier to achieve if the
speakers are placed along the short wall of the listening room.
Speaker Placement
Although the Sentinel Active Reference System may be placed in a variety of
positions relative to the walls of the room, it is still wise to apply the basic
guidelines described in this chapter to achieve optimal results. Plan on
placing the speakers along the short wall of the listening room. Then apply
the 4 : 10 : 4 ratio to establish the side wall distance (see page 51). The rear
wall distance should be greater than and not overly similar to the side wall
distance.
The suggested minimum distances for the Sentinel are 4 feet from the side
wall, and 8 feet from the rear wall (all distances are measured to the center
of the 9" woofer cone). This will provide the proper degree of bass
reinforcement, as well as minimize early reflections. There is no suggested
upper limit for the distances to the walls. Even a distance of 10 feet to one
wall and 15 feet to the other wall will provide suitable bass reinforcement, and
problems due to early reflections will be non-existent. However, regardless of
the absolute numbers used, the most even bass response will be attained
when the distances to the side wall and the rear wall are different by at least
33%.
The exemplary horizontal polar response of the Sentinel Active Reference
System makes large amounts of toe-in unnecessary. The optimum toe-in
position is between two and three degrees. In situations where strong
reflections from the side walls are a problem, pointing the speakers inward up
to a maximum of five degrees can be helpful.