Turbosound TA-880 user manual Bass Enclosure arraying, Aiming - directivity of the stack

user manual

TA-880

Bass Enclosure arraying

Aspect bass enclosures are most efficient when ground stacked in a block. Not only do they benefit from improved coupling when there are no air gaps between them, but they also couple to the ground. However, some of this energy may be absorbed by nearby obstructions such as barriers or a tightly-packed standing audience. Sound pressure levels may also be excessive for members of the audience if they are able to get too close to the enclosures. When stacking on the stage or on a platform, particularly outdoors, it is preferable to close the gap between the platform and the floor with sheets of plywood. This results in increased sound projection into the audience and less leakage backstage.

Aiming - directivity of the stack

The directivity of the bass stack will depend on its dimensions and curvature. A tall thin stack will disperse a lot in the horizontal plane and become narrow in the vertical plane and likewise a wide stack will narrow in the horizontal plane. There is usually an optimum compromise between the two so that a smooth transition can be obtained between the effect of the coupling of the two stacks down the centre line of the room and the effect of the individual stacks beaming on their axis. Also adding some curvature to the stack will help to increase the directivity of the stack especially in the higher frequencies.

Tall, thin bass stacks work best, preferably in blocks of six or eight bins high by two wide. When space permits use two or three of these blocks, placing the onstage block flush with and parallel to the stage, with a second and additional identical offstage blocks slightly separated from the first and angled outwards by 40°.

Stacking bass cabinets in a line in front of the stage will produce narrower dispersion in the horizontal plane, while giving wide vertical dispersion.

TA-880 user manual Page 42