B&C 10NSM76 – Superior 10-Inch Sealed-Back Neodymium Midrange for Ultra-Low Distortion
The B&C 10NSM76 is a dedicated sealed-back neodymium midrange driver that B&C claims offers the lowest distortion at a given output of any midrange available. With 100 dB sensitivity, 4.5% reference efficiency, a 1.6 T flux density that is the absolute highest of any driver in B&C’s entire LF range, and a cast aluminium sealed chassis that eliminates the need for a separate rear enclosure, the B&C 10NSM76 is purpose-built for one thing: delivering the cleanest, most controlled midrange output possible from a 10-inch cone.
The sealed-back design is the defining feature. The cast aluminium chassis forms a self-contained sealed enclosure behind the cone, providing simplified cabinet assembly and efficient thermal transfer from the motor to the surrounding air. There’s no need to design a sealed rear chamber or worry about rear-wave interference — the B&C 10NSM76 mounts directly into the baffle and operates as a complete, self-enclosed midrange section immediately.
With a 235 Hz – 3500 Hz bandwidth, a neodymium ring magnet, and availability in 8 and 16 Ω, the B&C 10NSM76 is ideal for dedicated midrange sections in three-way and four-way professional speaker systems — both direct-radiating and horn-loaded. At 4.55 kg, the neodymium motor keeps weight manageable for flown systems and touring cabinets. Connection is via 6.3 + 4.8 mm fast-on terminal tabs exclusively.
Design and Construction of the B&C 10NSM76
The B&C 10NSM76 uses a 76 mm (3-inch) aluminium voice coil wound on a glass fibre former. The 11 mm winding depth operating in a 9 mm magnetic gap yields 3.5 mm of linear one-way excursion (Xmax) with an additional 3.5 mm of travel (Xvar) before mechanical limits. The excursion is deliberately limited — in the 235–3500 Hz midrange band, minimal cone displacement generates high SPL, and keeping excursion short allows the driver to maximise sensitivity and minimise distortion.
The motor is extraordinary. A neodymium ring magnet in a T-pole configuration produces 1.6 T of flux density — the absolute highest of any driver in B&C’s entire product range, surpassing even the 10MD26’s 1.45 T and the 12FW76’s 1.35 T. That extreme flux concentration drives a force factor (Bl) of 21.5 Tm on the 33 g moving mass, creating a Bl/Mms ratio and acceleration factor that are unmatched in B&C’s 10-inch lineup. The 4.5% efficiency and 100 dB sensitivity are the direct result of this motor’s authority over the ultra-light cone assembly.
The cast aluminium sealed chassis is the engineering detail that makes the B&C 10NSM76 unique in B&C’s range. The sealed back provides a controlled, enclosed air volume behind the cone — eliminating rear-wave resonances and interactions that degrade midrange clarity in open-back or shared-chamber designs. The aluminium chassis also acts as a heatsink, conducting heat away from the motor and coil assembly for reduced power compression during sustained high-power operation.
The accordion surround provides high compliance with minimal mass — the same surround type used on the 320K/C-A full-range driver. The radial cone features WP waterproof treatment on the front side. A single spider handles suspension. At 4.55 kg, the B&C 10NSM76 is lighter than B&C’s ferrite 10-inch drivers despite carrying the most powerful motor in the entire LF range — the neodymium ring magnet delivers 1.6 T from a compact, lightweight assembly that a ferrite motor couldn’t match without adding several kilograms.
Performance and Applications for the B&C 10NSM76
The B&C 10NSM76 delivers 100 dB sensitivity and 4.5% reference efficiency across a 235 Hz – 3500 Hz bandwidth. This is a narrow-bandwidth midrange by design — the 235 Hz lower limit means it operates above the bass section, and the 3500 Hz upper limit hands off to a compression driver or tweeter. The narrow bandwidth allows every aspect of the driver to be optimised specifically for midrange reproduction, which is why B&C makes the bold claim about lowest distortion at a given output.
The Thiele–Small parameters reflect the sealed-back architecture. The 235 Hz Fs is the highest of any driver we’ve covered — confirming that the B&C 10NSM76 has no business reproducing bass frequencies. The Qts of 0.52 and EBP of 427 Hz — the absolute highest EBP in B&C’s entire range — define a driver with extreme motor control in its narrow operating band. The sealed back provides the controlled rear-loading that the driver needs, and the large 5 dm³ internal air volume gives the cone room to operate without back-pressure issues.
The 100 dB sensitivity from a dedicated midrange is critical for system design. In multi-way systems, the midrange section needs to match the sensitivity of both the bass driver below and the compression driver above — the B&C 10NSM76’s 100 dB output keeps it level with high-sensitivity woofers and compression drivers without requiring padding or disproportionate amplification. The 16 Ω variant enables series-parallel wiring in multi-driver midrange arrays.
Ideal applications for the B&C 10NSM76 include:
- Dedicated midrange sections in three-way and four-way professional speaker systems
- Horn-loaded midrange applications where the sealed back simplifies cabinet design
- Direct-radiating midrange in line arrays and touring speaker systems
- Systems requiring the lowest possible distortion from the midrange section
- Multi-driver midrange arrays using the 16 Ω variant for impedance management
Specifications – B&C 10NSM76
- Nominal Diameter: 250 mm (10 in)
- Nominal Impedance: 8 Ω
- Minimum Impedance: 7 Ω
- Nominal Power Handling: 400 W
- Continuous Power Handling: 800 W
- Sensitivity: 100 dB
- Frequency Range: 235 Hz – 3500 Hz
- Voice Coil Diameter: 76 mm (3 in)
- Winding Material: Aluminium
- Former Material: Glass Fibre
- Winding Depth: 11 mm (0.45 in)
- Magnetic Gap Depth: 9 mm (0.35 in)
- Flux Density: 1.6 T
- Magnet Material: Neodymium Ring
- Cone Shape: Radial
- Cone Treatment: WP Waterproof (front side)
- Surround Shape: Accordion
- Spider: Single
- Pole Design: T-Pole
- Chassis: Cast Aluminium (sealed back)
- Connection: 6.3 + 4.8 mm Fast-On Terminal Tabs
- Net Weight: 4.55 kg (10.03 lb)
Thiele–Small Parameters – B&C 10NSM76
- Fs: 235 Hz
- Re: 5.2 Ω
- Qes: 0.55
- Qms: 8.6
- Qts: 0.52
- Vas: 2 dm³ (0.07 ft³)
- Sd: 320 cm² (49.6 in²)
- η0: 4.5%
- Xmax: 3.5 mm
- Xvar: 3.5 mm
- Mms: 33 g
- Bl: 21.5 Tm
- Le: 0.9 mH
- EBP: 427 Hz
Mounting Information – B&C 10NSM76
- Overall Diameter: 291 mm (11.46 in)
- Bolt Circle Diameter: 274 mm (10.79 in)
- Baffle Cutout Diameter: 234 mm (9.21 in)
- Depth: 130 mm (5.12 in)
- Flange and Gasket Thickness: 12 mm (0.47 in)
- Air Volume Occupied by Driver: 5 dm³ (0.18 ft³)
- Net Weight: 4.55 kg (10.03 lb)
Conclusion – B&C 10NSM76 Midrange Driver
The B&C 10NSM76 is the reference midrange driver in B&C’s range — a sealed-back, narrow-bandwidth specialist carrying the most powerful motor B&C has ever put in an LF-format driver. The 1.6 T flux density, 21.5 Tm force factor, and 427 Hz EBP are all absolute range-topping figures, and they serve a single purpose: producing 100 dB of midrange output with the lowest distortion possible. B&C’s claim of lowest distortion at a given output is backed by the engineering — the sealed back eliminates rear-wave interference, the neo ring magnet provides extreme flux uniformity, and the narrow bandwidth allows every component to be optimised specifically for midrange reproduction.
The sealed-back cast aluminium chassis is a genuine system design advantage. It eliminates the need to design and build a separate sealed midrange chamber inside the speaker cabinet — the B&C 10NSM76 mounts directly to the baffle and its own rear enclosure is built in. For cabinet builders, this saves design time, internal volume, and assembly complexity. The aluminium chassis also doubles as a heatsink, reducing power compression during sustained 400 W AES operation.
For three-way and four-way professional speaker systems, horn-loaded midrange sections, line arrays, and any application where the midrange needs to match 100 dB woofer sensitivity with the lowest possible distortion, the B&C 10NSM76 is the 10-inch midrange that defines the category. Mount it, wire it, and let the 1.6 T motor do the work — that’s the promise of a sealed-back midrange done right.
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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.
