Turbosound LMS-D26, LMS-D6, LMS-D24 user manual Turbobass Directivity, Bass Enclosure arraying

user manual

TA-890

Turbobass Directivity

The Aspect series TA-890L bass bin and the TSW-218 subwoofer are “Turbobass” devices, comprising horn-loaded drivers. Whilst this horn loading does aid in tuning the device and adding some sensitivity, the relationship between horn length and the bandwidth covered by the enclosures means that each source is effectively an omni-directional point source.

Therefore any LF pattern control experienced when using an Aspect system derives from adjacent enclosures within an array or from the relationship of a left to right stack

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 whereas 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 stopping beaming at higher frequencies.

TA-890 user manual Page 38