LONG STROKE - DOUBLE MAGNET Hard Paper proprietary cone materials made in-house for consistency. Low damping SBR rubber surround with high exertion and resilience. Open structure cast frame for reduced reflections and compression. Aluminium alloy for light weight, non-magnetic and extra rigidity. Shorting Copper cap on pole piece. Non-inductive 75.6mm coil former. The goal of SB Acoustics with their NRX series of performance drivers has been to design a simple, yet optimised speaker driver at a competitive price to achieve a high performance to cost ratio for their customers who appreciate premium quality audio. To this end, SBA are proud to present their NRX series: Close attention to design engineering with manufacturing materials and processes to optimize performance. The coil former material is fibre glass. It is fundamental to use a non-conducting former material to ensure a low mechanical loss and high Qms. We prefer the damping to be electrical rather than mechanical, as this puts the amplifier in control. This is important if you want the driver to accurately reproduce the electrical signal. The woofers feature large diameter copper wire voice coils for improved power handling and allows for efficient ventilation through the centre pole. The basket is also vented under the spider to reduce compression to an absolute minimum, which is necessary to ensure good dynamics. The motor structure is simple, but all dimension have been optimizes to ensure BL symmetry and good saturation of the iron in the coil region. The surrounds are low damping SBR with a low shore hardness, which ensures good linearity. Stability is obtained by making the rolls just thick enough to withstand the high pressure in smaller cabinets without “collapsing”. The geometry of the surround and spider start limiting at the same time with a linear region slightly exceeding that of the coil overhang. This all ensures good linearity without hard clipping or mechanical damage to the cone at high levels. The cone material is made in-house using a proprietary blended hard stiff natural materials we call NOREX®. Cone stiffness is important to a woofer, as it should behave like a piston that moves air without flexing. This clearly improves bass reproduction. The baskets are cast aluminium to insure a rigid open structure. This makes the optimum foundation for the moving parts and has been designed not only to look good but also to offer some unique mounting options. They even come with gaskets pre-mounted. The copper cap also reduces the inductance. This results is increased bandwidth and improved transient response.