B&C 8NSM64 8″ Sealed Midrange Driver
The B&C 8NSM64 is a professional 8-inch sealed back midrange driver engineered for high-output mid-frequency reproduction in demanding sound reinforcement applications. Designed around a sealed cast aluminium chassis and high-strength neodymium motor assembly, the B&C 8NSM64 is optimized for applications where controlled bandwidth, reduced distortion, and simplified cabinet integration are critical.
Unlike conventional low-frequency drivers, the B&C 8NSM64 is purpose-built as a dedicated sealed midrange transducer, making it suitable for direct radiating and horn-loaded midrange applications where exceptional efficiency and controlled frequency response are required. The sealed chassis construction eliminates the need for dedicated rear chamber design, simplifying enclosure construction while improving thermal transfer characteristics.
Key Features
- 250 W nominal power handling
- 500 W continuous program power capacity
- 64 mm (2.5 inch) aluminium voice coil
- Sealed cast aluminium chassis construction
- High-strength neodymium ring magnet assembly
- 100 dB sensitivity
- 245 Hz – 2000 Hz frequency response
- Optimized for direct radiating and horn-loaded midrange applications
- Waterproof front cone treatment
- Dedicated narrow-bandwidth midrange design for low distortion performance
Sealed Back Midrange Design
The defining feature of the B&C 8NSM64 is its fully integrated sealed back architecture, designed specifically for simplified cabinet assembly and improved system integration. By eliminating the requirement for a separate rear chamber, the driver significantly reduces enclosure complexity while maintaining predictable acoustic loading.
The sealed cast aluminium chassis also improves thermal transfer to surrounding air, assisting heat dissipation during continuous high-output operation. This approach allows the driver to maintain more stable thermal performance while supporting demanding professional applications.
B&C designed the NSM series specifically as dedicated narrow-bandwidth midranges, prioritizing low distortion performance within the intended operating range rather than attempting broadband operation.
Neodymium Motor Structure and Magnetic Performance
The B&C 8NSM64 utilizes a neodymium ring magnet motor structure, providing strong magnetic force while minimizing overall driver weight. The motor assembly generates a measured 1.55 T flux density, supporting high sensitivity and strong cone control throughout the operating range.
The driver achieves a high 22 Tm BL factor, contributing to efficient motor force and maintaining controlled cone movement during high-output operation. Combined with the lightweight moving assembly, the motor structure contributes to the driver’s strong efficiency characteristics and low distortion behavior.
A T-pole motor design further contributes to stable magnetic behavior and predictable performance during continuous operation.
Voice Coil Construction and Thermal Performance
At the center of the B&C 8NSM64 is a 64 mm aluminium voice coil wound on a glass fibre former. This construction balances low moving mass with the thermal stability required for professional sound reinforcement applications.
The driver supports 250 W nominal power handling and 500 W continuous program power handling, allowing it to maintain performance in demanding midrange applications requiring sustained output levels. The large voice coil geometry contributes to improved heat dissipation while supporting consistent long-term performance.
The relatively low 19 g moving mass further contributes to fast transient response and improved articulation throughout the intended operating bandwidth.
Cone and Suspension Design
The B&C 8NSM64 utilizes a radial cone profile combined with a double-roll surround configuration. This geometry supports controlled movement while maintaining the responsiveness required for dedicated midrange operation.
A single spider suspension system maintains mechanical stability and predictable cone behavior throughout the operating bandwidth. The cone assembly incorporates WP waterproof front-side treatment, helping improve durability in professional portable and installed environments.
The carefully optimized suspension geometry contributes to the driver’s narrow-band low-distortion behavior and high sensitivity characteristics.
Technical Specifications
Nominal Diameter: 200 mm (8 in)
Nominal Impedance: 8 Ω
Minimum Impedance: 8.2 Ω
Nominal Power Handling: 250 W
Continuous Program Power: 500 W
Sensitivity: 100 dB
Frequency Range: 245 Hz – 2000 Hz
Voice Coil Diameter: 64 mm (2.5 in)
Winding Material: Aluminium
Former Material: Glass Fibre
Winding Depth: 13 mm
Magnetic Gap Depth: 10 mm
Flux Density: 1.55 T
Magnet Material: Neodymium Ring
Cone Shape: Radial
Surround Shape: Double Roll
Spider Design: Single
Pole Design: T-Pole
Cone Treatment: WP Waterproof Front Side
Thiele-Small Parameters
Fs: 245 Hz
Re: 5.7 Ω
Qes: 0.35
Qms: 9.3
Qts: 0.34
Vas: 1.5 dm³
Sd: 220 cm²
η₀: 4.5 %
Xmax: 2 mm
Xvar: 1.7 mm
Mms: 19 g
BL Factor: 22 Tm
Le: 0.6 mH
EBP: 700 Hz
Mounting Information
Overall Diameter: 239 mm
Bolt Circle Diameter: 222 mm
Baffle Cutout Diameter: 200 mm
Depth: 115 mm
Flange and Gasket Thickness: 16 mm
Air Volume Occupied by Driver: 3.5 dm³
Net Weight: 4.55 kg
Shipping Weight: 5.15 kg
Shipping Box: 295 × 314 × 175 mm
Recone Kit: RCK008NSM648
Applications
The B&C 8NSM64 is engineered specifically for professional midrange applications requiring controlled bandwidth, high sensitivity, and reduced distortion. Its sealed construction, high-efficiency neodymium motor, and dedicated narrow-band operating range make it suitable for:
- Direct radiating midrange systems
- Horn-loaded midrange applications
- Professional touring loudspeaker systems
- High-output multi-way loudspeakers
- Installed sound reinforcement systems
- Compact professional audio systems
For system designers requiring a dedicated sealed midrange transducer optimized for efficiency and controlled response, the B&C 8NSM64 provides a purpose-built solution designed specifically for professional mid-frequency reproduction.
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About B&C Speakers S.r.L.
B&C Speakers products are built in Bagno a Ripoli (Florence), Italy., ensuring high quality products to suite your speaker building requirements. Their 10,500 square meter facility incorporates highly sophisticated automation and quality control. Over the years they become one of the world leaders in the Professional Audio market, a brand recognized everywhere as a premium product that offers excellent value to the consumer.
