Design and Construction of Loudspeakers with Low-Bl Drivers for Low-frequency Active Noise Control Applications
* Presenting author
The concept of the so-called low-Bl drivers is exploited, through the design and construction of small vented loudspeakers. Their high compliance and low-frequency resonance provide high-efficiency response in a limited frequency region and allow the implementation of small cabinet volumes. Their purpose is to be the elementary building components of a compound source for low-frequency noise control applications. The combination of such sources can lead to dipole or multipole set-ups, in which the radiation directivity pattern in open spaces and modal coupling in closed spaces can be controlled via the parameters of the individual driving signals.The construction constraints of the cabinet are accounted for, considering its design optimization. A low-volume cabinet with ports tuned close to the driver’s resonance frequency is constructed to extend the loudspeaker’s output at low frequencies. The impact of the position, the dimension and the number of the enclosure’s tubes to the loudspeaker’s frequency response are examined through measurements. The design analysis and experiments show the direction to their proper construction. The implementation of such loudspeakers for low-frequency noise control applications is advantageous in small rooms, where the available space is of great concern.