Low Impedance Voice Coils for Improved Loudspeaker Efficiency

Niels Elkjær Iversen, Arnold Knott, Michael A. E. Andersen

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

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In modern audio systems utilizing switch-mode amplifiers the total efficiency is dominated by the rather poor efficiency of the loudspeaker. For decades voice coils have been designed so that nominal resistances of 4 to 8 Ohms is obtained, despite modern audio amplifiers, using switch-mode technology, can be designed to much lower loads. A thorough analysis of the loudspeaker efficiency is presented and its relation to the voice coil fill factor is described. A new parameter, the drivers mass ratio, is introduced and it indicates how much a fill factor optimization will improve a driver’s efficiency. Different voice coil winding layouts are described and their fill factors analyzed. It is found that by lowering the nominal resistance of a voice coil, using rectangular wire, one can increase the fill factor. Three voice coils are designed for a standard 10” woofer and corresponding frequency responses are estimated. For this woofer it is shown that the sensitivity can be improved approximately 1 dB, corresponding to a 30% efficiency improvement, just by increasing the fill factor using a low impedance voice coil with rectangular wire.
Original languageEnglish
Title of host publicationProceedings of 139th International Audio Engineering Society (AES) Convention
Number of pages10
PublisherAudio Engineering Society
Publication date2015
Article number9389
Publication statusPublished - 2015
Event139th International Audio Engineering Society (AES) Convention - The Jacob Javits Center, New York City, United States
Duration: 29 Oct 20151 Nov 2015


Conference139th International Audio Engineering Society (AES) Convention
LocationThe Jacob Javits Center
CountryUnited States
CityNew York City
Internet address

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