AIC: Active Impedance Control


Magneto-dynamic loudspeakers are affected from a wide variety of problems due to the voice coil inductance. This inductance is not a constant parameter but is dependent on the frequency, the displacement and the actual current flowing in the coil. Moreover these last two dependencies are also non-linear. Several causes of distortion, affecting mainly the vocal range, are derived from these phenomena. A practical solution to minimize the inductance is investigated. This solution is based on additional fixed coil positioned in the gap provided with 2 additional terminals offering various connection possibilities. This device is referred as A.I.C. (Active Impedance Control). Advantages of this approach will be discussed and measurements results will be shown as well.