Small drivers vs big drivers

@shadorne raises an important point. During heavy excursions of its cone, a woofers voice coil heats up, changing the drivers electrical characteristics, and therefore its sound. One of the functions of the Servo-Feedback circuit in Rythmik subs is electronic compensation for the change in the woofers electrical characteristics due to voice coil temperature. No non-feedback woofer or sub is capable of that feat, one of the reasons for the uniquely clean (low distortion) sound of Rythmik subs. Sound like a sales pitch? Too bad ;-) .

The Servo-Feedback circuit also minimizes differences between the 12", 15", and 18" Rythmik woofers. Their sound characteristics are identical, the difference between them being in their maximum SPL capability. Rythmik also offers subs with 8" woofers, for those clinging to the idea that smaller woofers are "faster" than larger ones.

The ability to create a wide/big soundstage and the ability to reproduce low frequencies are two completely different matters (except that the sound of a large recording venue---cathedrals, churches, theaters---are of very, very low frequencies).

The size of the drivers in a loudspeaker, assuming you are talking about cone/dynamic drivers, has nothing to do with the speakers ability to create a wide/big soundstage. The size of a woofer, on the other hand, is very much related to how much air it can move at low frequencies. But size isn't everything, right girls? ;-)