Rigid Diaphragm Technology (RDT®) mid-range and bass drivers
Bass and mid-range driver cones use RDT, a unique technology developed specifically by Monitor Audio’s engineers for the Platinum series of loudspeakers*. Designed to reduce mass and increase cone stiffness, RDT applies ultra-thin skins of C-CAM to a core of honeycomb Nomex®** material, creating a structure which is extremely light but incredibly rigid. At only 40μm thick, the C-CAM skins are half the thickness of a human hair, yet when bonded to the hexagonal honeycomb core they form an RDT cone, which is 150 times more rigid than a single layer of 200μm C-CAM alloy, but has a fraction of the overall mass. These properties allow the cone to operate as a lightning- fast piston for a clearer more natural sound. The cone’s new concave geometry has been refined by FEA analysis to provide a smooth frequency response and eradicate break-up.
To optimise the performance of the RDT cone, Monitor Audio has developed motor systems in which a focused magnetic gap and copper eddy rings work together to produce a higher level of linearity and lower distortion than was previously possible. Magnet plates and poles are CNC machined to very precise standards, ensuring consistency.
The Platinum mid-range driver utilises an ‘under hung’ voice coil design to further optimise linearity and reduce distortion. High energy NeFeB rare earth magnets are used for high efficiency, and a large 2” (50mm) voice coil is specified to handle powerful dynamic impulses. Its RDT cone is driven directly by the voice coil to provide an extremely articulate mid-range response and seamless integration with the other drivers.
Platinum’s bass drivers use long-throw voice coil windings for long excursions at high power levels, giving deeper, more controlled and potent bass. The larger 8” (200mm) drivers employ dual spider arrangements for extra stability. Their direct-drive RDT cones have no dust cap or joints to interfere with the driver response over the working band.
*PLW-15’s driver is C-CAM only
**Nomex® is a registered trademark of E.I DuPont de Nemours and Company
