The 12NDA520 is a 12" mid-low transducer created for compact reflex 2-way enclosures and designed to be coupled with typical 1" and 1.4" compression drivers. It can also be used in mid-low applications on modern line-array systems. Its features and design characteristics make it extremely defined in mid-range frequencies and offer a significant and consistent bottom-end, making the product also suitable for monitoring applications. The 12NDA520 incorporates our proprietary Active Impedance Control technology (AIC), consisting of an additional coil fixed on the pole piece and connected in parallel to the moving coil. The magnetic field generated by this coil has the following effects: 1) Impedance linearization 2) Acoustic and electric phase linearization 3) Significant increase of sensitivity and total SPL 4) Total harmonic distortion reduction 5) Constant power transfer By not absorbing the moving coil's electromagnetic energy, AIC offers substantial advantages relating to the quality of sound. The neodymium magnet assembly developed by Eighteen Sound engineers assures high flux concentration, low power compression and excellent heat exchange since the external magnet configuration is considerably more efficient than traditional under-pole magnet topology. This results in high levels of force factor and power handling with an optimum power to weight ratio. The curvilinear cone, created from a high damping wood pulp, has been designed to achieve the best possible linearity within its intended frequency range. The 12NDA520 employs our Interleaved Sandwich Voice coil (ISV) technology in which a high strength fiberglas former carries windings on both the outer and inner surfaces to achieve a mass balanced coil. The final result is an extremely linear motor assembly with a reduced tendency for eccentric behavior when driven hard. A proprietary humidity-block cone treatment makes the transducer suitable for outdoor use in adverse weather conditions. In addition, a special coating applied to both the top and back plates makes the 12NDA520 far more resistant to the corrosive effects of salts and oxidization.