Omnidirectional point source

Constant radiation pattern via FIR equalizer

In this study, Casper Jansen presents a DIY speaker that approximates an omnidirectional point source to achieve a constant radiation pattern. A 10-cm woofer ventilates through a PVC tube with a 5-cm diameter, and a tweeter ventilates through a 3D-printed cone with a 10-mm opening. The resulting erratic frequency response (with resonance peaks up to 15 dB) is corrected using a time-domain FIR filter based on the least-squares method (Tsujino & Elliott). A follow-up measurement after eight months shows that temperature effects and a cone resonance around 5 kHz lead to deviations.

References to the documents