Saturday, May 20, 16:30 — 18:00
Finn T. Agerkvist (Chair)
P08-01 Position Dependence of Fractional Derivative Models for Loudspeaker Voice Coils with Lossy Inductance
Alexander W. King (Presenting Author), Finn T. Agerkvist (Author)
Commonly used models of moving-coil loudspeaker voice coils, which include effects from eddy current losses, are either inaccurate or contain an abundance of parameters and are difficult to extend to the nonlinear domain. On the contrary, fractional derivative models accurately describe the frequency and position dependence of the lossy inductance, with meaningful connections to the underlying physics, while keeping the number of parameters low. These fractional derivatives are also compatible with state-space polynomial methods of modeling nonlinear behavior. It is shown that the fractional order derivative approaches a value of 1, corresponding to an ideal inductance, when the voice coil is completely outside the magnetic system. Finally, the developed model reveals details about the effect of conductive voice coil formers.
Convention Paper 9723
P08-02 Model for Evaluation of Power Consumption of Vented Box Loudspeakers
Filip Sommer Madsen (Presenting Author), Niels Elkj'r Iversen (Author), Arnold Knott (Author), Søren Thorsen (Author)
In the design of mobile sound systems an estimation of power consumption must be made in order to choose a battery of appropriate size and cost. However poor methods for power estimation tend to result in large and costly batteries. This paper aims to present a more precise method for estimating power consumption for a vented box sound system. Instead of simplifying a loudspeaker system as a purely ohmic resistance, its mechanical and acoustic parameters are used to create a state space model. Despite deviations at high frequencies, the state space model is at least twice as accurate at estimating the power consumption than simplifying the speaker as a resistor.
Convention Paper 9724
P08-03 Assessment of the Radiation Mode Method for In Situ Measurements of Loudspeaker Systems
Maryna Sanalatii (Presenting Author), Régine Guillermin (Author), Philippe Herzog (Author), Jean-Christophe Le Roux (Author), Manuel Melon (Author), Nicolas Poulain (Author), Clément Vasseur (Author), Lucas Vindrola (Author)
In this paper the radiation mode method is used to measure the frequency response and the directivity pattern of loudspeaker systems. This method, which has been successfully applied to speaker measurement in free field conditions, is now tested in a large non-anechoic hall. Two closed box systems and a switchable bi-directive/cardioid subwoofer have been used. Each system is measured first in an anechoic chamber and then in the large hall. The radiation method is then applied to the two different measurement data sets. Results show a good agreement between both conditions. Finally, the influence of the mesh coarsening is studied.
Convention Paper 9725