Time doman measurement of moving coil loudspeaker driver parameters

A method for measuring the small-signal parameters of a moving-coil electromagnetic transducer driver, comprising:

• mounting said driver in free air;
• coupling the electrical input terminals of said driver to a series circuit including a switching means, a source of DC voltage, and a series resistance;
• closing said switching means such that a DC current flows through said series circuit including said driver;
• measuring the DC source voltage V.sub.g appearing across the output terminals of said DC voltage source;
• measuring the DC voltage V.sub.vc appearing across the terminals of said driver;
• calculating the voice coil resistance R.sub.E of said driver and the steady state current I.sub.go flowing in said series circuit using said measured voltages V.sub.g and V.sub.cc ;
• opening said switch;
• measuring the AC voltage v.sub.vc (t) appearing across the terminals of said driver as a function of time;
• determining the amplitude coefficient A, the attenuation factor .alpha., and the frequency .omega..sub.d of said measured AC voltage;
• and
• calculating the free-air frequency of resonance .omega..sub.S, the electrical quality factor Q.sub.ES, the mechanical quality factor Q.sub.MS, and the total quality factor Q.sub.TS for said driver using said amplitude coefficient, said attenuation factor, and frequency .omega..sub.d.