Enhanced construction of the direct radiator electrodynamic loudspeaker

Abstract

This paper first presents the principle of the electrodynamic loudspeaker. It particularly shows how few evolutions occurred since the first device was designed. Then, it describes the loudspeaker drawbacks whose sources lie in the motor – especially because of the iron-, the moving part and the suspension. Furthermore, the major goal of this paper is to propose examples of evolutions which suppress some of the drawbacks. So, the motors presented are ironless, made with permanent magnets only. Their structure can be optimized to create very uniform magnetic fields in the air gap where a short coil is totally submitted to the field. Moreover, the elastomer suspensions are replaced by ferrofluid seals which guide the moving part. Besides, the moving part itself becomes a lightweight rigid bulk piston. Eventually, these proposals prove that evolution of the electrodynamic loudspeaker is still possible. And the possibilities are of course myriads.