High back emf, high pressure subwoofer having small volume cabinet, low

Abstract

A small, compact subwoofer cabinet; openings in two cabinet walls; first and second cages mounted on respective ones of the walls in alignment with the openings; a voice coil driven driver including an annular magnet weighing approximately 225 oz. affixed to the first cage; a stationary pole piece extending through the magnet and defining a magnetic gap therebetween; a voice coil mounted on a cylindrical voice coil former positioned within the gap; a cone affixed to one end of the former; a first flexible surround secured to the outer end of the cone and to the first cage; a flexible spider secured to the former and to the first cage; a mass driven driver including a mass aggregating about 2 lbs.; a second flexible surround secured to the mass and to the second cage; a flexible spider attached to the second cage and to the mass; both surrounds having a thickness of about 0.1', an edgeroll having a diameter of about 1.5', and capable of standing off internal pressures up to about 3 lbs./in.sup.2 ; a drive amplifier capable of delivering up to about 2,700 watts to a nominal 4 ohm resistive load and swinging up to about 104 volts for delivering (+).DELTA.v and (-).DELTA.v drive signals to the voice coil for driving the voice coil driven driver through a peak-to-peak stroke of about 2.5' while generating a large back emf sufficient to counter the applied emf and minimize current flow in the voice coil.