The BMS 4599ND dual diaphragm driver incorporates two identical 3.5” concentric annular ring diaphragms, connected to a common 2” throat, providing extremely high acoustical output.
 
The patented design of the BMS 4599ND is a result of extensive dedicated research and development, providing dramatic improvement in efficiency, power handling, dynamic response and clarity.
In fact the double voice coil/diaphragm assembly provides 6 dB higher maximal SPL compared to an equal single voice coil driver.

Two large annular diaphragms cover the frequency range 200 Hz to 9000 Hz with a smooth, linear response.
The high diaphragm excursion of maximal +/- 0.8 mm results in high output and increased power handling up to 2600 W peak.

The unique voice coil technology employs a high purity copper wire wound inside and outside of the Kapton™ former to improve the heat dissipation, dramatically increasing the acoustic output and reliability of the driver, while minimizing the power compression.
The voice coils may be driven in parallel, serial or separately for optimal amplifier loading, allowing a single channel of 4, 8, or 16 Ohm as well as double channel of 2x 4 Ohm or 2x 8 Ohm.
The use of high grade neodymium magnets provides improved performance while significantly reducing transducer weight.