The 12NMB420 is a 12 inch neodymium mid-bass transducer designed for professional monitoring and sound reinforcement. At the heart of this speaker is a carefully engineered drive system, designed to assure linear, low-distortion output, high power capability and efficient heat transfer. The most extended bass, lowest distortion and best control is usually realized in properly designed vented enclosures. In such designs, the vent, or port, actually provides the lowest octave of output. The excursion of the 12NMB420 at these frequencies is much reduced compared to sealed enclosures, directly reducing harmonic distortion and the possibility of speaker bottoming. Typical vented enclosure sizes range from 40lit up with tunings from 50 to 60Hz. Low frequency equalization is suggested and normally added, in order to improve the bass output if the system will work without subwoofer. The recommended amplifier size ranges from 250 up to 500W. The onboard copper sleeve positioned in the gap and coupled with SDR (Single Demodulating Ring) results in optimum balance for reproducing instantaneous peaks on mid frequencies, reducing intermodulation distortion. The external magnet typology neodymium magnet assembly assures high flux concentration, low power compression and excellent heat exchange since the external magnet configuration is considerably more efficient than the traditional under - pole magnet topology. This allows to obtain high levels of force factor and power handling with a power to weight ratio at the upper level. The high quality paper cone has a smooth, curvilinear profile design that eliminates bell-mode resonances within the intended frequency range. This is carried by a specially treated and damped double triple-roll linen suspension designed to control excursion maintaining the piston action linearity. The 12NMB420 employs a 64mm Interleaved Sandwich Voice coil (ISV), in which a high strength fiberglass former carries windings on both the outer and inner surfaces to achieve a mass balanced coil, resulting in an extremely linear motor assembly with reduced tendency to eccentric behavior when driven hard.