Double treated, hard paper cone designed to be very stiff without losing the damping capability, together with a natural rubber surround produces a well behaved roll off characteristic and reduces potential resonance problems. Large magnet system with bumped back plate together with a long 4-layer voice coil gives long linear excursion. The magnet system has a T-shaped cross section of the pole piece for low modulation distortion. Extremely stiff and stable injection moulded metal basket keeps the critical components in perfect alignment. Large windows in the basket both above and below the spider reduce sound reflexion, air flow noise and cavity resonances.