Avalon Acoustics Sentinel manual Early Reflections, Speaker Placement

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.

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