AES Journal Forum

A Model of Loudspeaker Driver Impedance Incorporating Eddy Currents in the Pole Structure

Document Thumbnail

Measurememts of electrodynamic drivers show a blocked-cone impedance which is often dominated by a -jw component. A simple theory shows that eddy currents in the iron pole structure are responsible for this behavior. A more complex theory shows a transition between such semi-inductive behavior at high frequencies to a normal inductive behavior at low frequencies, but a vast reduction of the effective permeability of the iron must be invoked to explain the measured data. This reduction is due to the effective demagnetizing gaps in the pole structure. Other aspects of the eddy currents concern the asymmetric drag force on a slotted aluminum voice-coil former, the direct thermal heating of the pole structure by the eddy currents, the electrical compensation of the -jw semi-inductive impedance, and the current waveforms expected when a step or impulse voltage is applied to the driver.

JAES Volume 37 Issue 3 pp. 119-128; March 1989
Publication Date:

Click to purchase paper as a non-member or you can login as an AES member to see more options.

No AES members have commented on this paper yet.

Subscribe to this discussion

RSS Feed To be notified of new comments on this paper you can subscribe to this RSS feed. Forum users should login to see additional options.

Start a discussion!

If you would like to start a discussion about this paper and are an AES member then you can login here:

If you are not yet an AES member and have something important to say about this paper then we urge you to join the AES today and make your voice heard. You can join online today by clicking here.

AES - Audio Engineering Society