B&C 320K/C-A – Superior 12-Inch Full-Range Driver for High-Sensitivity Applications
The B&C 320K/C-A is a 12-inch full-range driver delivering 101 dB sensitivity, 5.4% reference efficiency, and a massive 80 Hz – 16000 Hz bandwidth from a single transducer weighing just 4.6 kg. This isn’t a bass driver or a woofer — it’s a true full-range unit designed to reproduce everything from low-mid fundamentals through the high treble without requiring a separate tweeter or compression driver. The B&C 320K/C-A covers the kind of bandwidth that most speaker systems need two or three drivers to achieve.
The 101 dB sensitivity and 5.4% efficiency are the headline numbers — this is one of the most efficient 12-inch drivers available from any manufacturer. The 27 g moving mass is the engineering behind those figures: an ultra-light cone assembly that responds instantly to the input signal, producing output with the kind of immediacy and transient speed that heavier-cone drivers can’t replicate. A shorting copper cap extends the high-frequency response, keeping the output smooth and usable well into the treble region.
Available in both 8 Ω and 16 Ω variants, the B&C 320K/C-A is built for guitar amplifier cabinets, single-driver full-range PA speakers, vocal reinforcement systems, and any application where a single transducer needs to cover the entire audible frequency range with maximum efficiency and minimum amplifier power.
Design and Construction of the B&C 320K/C-A
The B&C 320K/C-A uses a 38 mm (1.5-inch) copper voice coil wound on a kraft paper former. The kraft paper former is a deliberate material choice — it’s lighter than glass fibre and contributes to the extraordinarily low 27 g moving mass that makes the driver’s extreme efficiency possible. The 9 mm winding depth operating in a 9 mm magnetic gap yields 2 mm of linear one-way excursion (Xmax). The short Xmax is by design — this is a sensitivity-first driver, not a displacement driver, and every gram of moving mass has been eliminated in pursuit of maximum output per watt.
The motor uses a ferrite magnet in a straight pole configuration, producing an impressive 1.4 T of flux density — one of the highest flux figures of any ferrite-motored driver in B&C’s range — and a force factor (Bl) of 12.2 Tm. That 1.4 T flux driving the 27 g moving mass creates the extreme acceleration factor responsible for the 5.4% reference efficiency. The motor grips the featherweight cone assembly with authority that produces instantaneous transient response — exactly the kind of snappy, dynamic character that guitar players and vocal reproduction demand.
A shorting copper cap on the pole piece is the key to the B&C 320K/C-A’s extended high-frequency response. The copper cap reduces voice coil inductance rise at higher frequencies, keeping the impedance curve flatter and allowing the driver to maintain output up to 16000 Hz — well into the treble region where most 12-inch drivers have rolled off completely. Without the copper cap, the driver’s high-frequency response would fall off much sooner.
The surround is an accordion type — a pleated fabric design that provides high compliance with minimal mass, supporting the full-range excursion behaviour and upper-frequency output that the driver requires. The radial cone has no waterproof treatment, keeping the moving mass as low as possible. A single spider handles suspension. At 4.6 kg and 136 mm deep, the B&C 320K/C-A is compact and light — easy to build into guitar cabinets, vocal columns, and single-driver enclosures of all kinds.
Performance and Applications for the B&C 320K/C-A
The B&C 320K/C-A delivers 101 dB sensitivity and 5.4% reference efficiency across an 80 Hz – 16000 Hz bandwidth. That 5.4% efficiency means this driver converts more than five watts out of every hundred into acoustic energy — the highest conversion rate of any 12-inch driver in B&C’s range by a significant margin. A 30 W tube amplifier driving the B&C 320K/C-A produces output that would require well over 100 W into a typical 95 dB woofer to match.
The Thiele–Small parameters tell the story of a full-range driver rather than a bass transducer. The 82 Hz Fs means the B&C 320K/C-A doesn’t reach into deep bass — it’s designed to reproduce content from the low-mid range upward. A Qts of 0.5 and an EBP of 158 Hz place it on the sealed/vented boundary, and B&C recommends a 60-litre (2.12 ft³) vented enclosure tuned to 75 Hz. That high tuning frequency confirms the driver’s intent: maximum output and efficiency in the mid-range and upper-bass frequencies, not sub-bass extension.
The 16000 Hz upper limit is what makes the B&C 320K/C-A a genuine full-range driver. Most 12-inch woofers roll off by 2000–3000 Hz and require a compression driver or tweeter to cover the upper frequencies. The B&C 320K/C-A handles the entire range itself, making it ideal for single-driver speaker designs where simplicity and natural tonal coherence matter more than extreme low-frequency extension. The shorting copper cap keeps the treble response smooth and extended without the harshness that uncompensated inductance rise would cause.
Ideal applications for the B&C 320K/C-A include:
- Guitar amplifier cabinets (1×12, 2×12, 4×12 configurations)
- Single-driver full-range PA and vocal reinforcement speakers
- High-efficiency vocal columns and speech reinforcement systems
- Vintage-style PA systems where maximum sensitivity from low-power amplification is essential
- Multi-driver parallel configurations using the 16 Ω variant for impedance management
Specifications – B&C 320K/C-A
- Nominal Diameter: 320 mm (12 in)
- Nominal Impedance: 8 Ω
- Minimum Impedance: 6.3 Ω
- Nominal Power Handling: 120 W
- Continuous Power Handling: 240 W
- Sensitivity: 101 dB
- Frequency Range: 80 Hz – 16000 Hz
- Voice Coil Diameter: 38 mm (1.5 in)
- Winding Material: Copper
- Former Material: Kraft Paper
- Winding Depth: 9 mm (0.37 in)
- Magnetic Gap Depth: 9 mm (0.35 in)
- Flux Density: 1.4 T
- Magnet Material: Ferrite
- Cone Shape: Radial
- Cone Treatment: None
- Surround Shape: Accordion
- Spider: Single
- Pole Design: Straight Pole
- Net Weight: 4.6 kg (10.14 lb)
Thiele–Small Parameters – B&C 320K/C-A
- Fs: 82 Hz
- Re: 5.4 Ω
- Qes: 0.52
- Qms: 13.3
- Qts: 0.5
- Vas: 53 dm³ (1.87 ft³)
- Sd: 522 cm² (80.91 in²)
- η0: 5.4%
- Xmax: 2 mm
- Mms: 27 g
- Bl: 12.2 Tm
- Le: 1.1 mH
- EBP: 158 Hz
Mounting Information – B&C 320K/C-A
- Overall Diameter: 316 mm (12.44 in)
- Bolt Circle Diameter: 298 mm (11.73 in)
- Baffle Cutout Diameter: 286 mm (11.26 in)
- Depth: 136 mm (5.35 in)
- Flange and Gasket Thickness: 12 mm (0.47 in)
- Air Volume Occupied by Driver: 3 dm³ (0.11 ft³)
- Recommended Enclosure Volume: 60 dm³ (2.12 ft³)
- Recommended Tuning Frequency: 75 Hz
Conclusion – B&C 320K/C-A Full-Range Driver
The B&C 320K/C-A is a fundamentally different kind of driver from the woofers and subwoofers that make up most of B&C’s LF range. It’s a true full-range transducer — 80 Hz to 16000 Hz from a single cone, no tweeter required. The 101 dB sensitivity and 5.4% efficiency make it one of the most efficient 12-inch drivers available from any professional manufacturer, and the 27 g moving mass ensures that every watt of input translates into immediate, dynamic acoustic output.
The trade-off is simple and honest: 120 W AES power handling and 2 mm of Xmax mean this is not a high-power bass driver. The B&C 320K/C-A earns its output through efficiency, not brute force — and in applications where that approach makes sense, nothing in B&C’s range delivers more output per watt across a wider bandwidth. A good 30 W tube amp driving this driver fills a room with authority.
For guitar cabinets, vocal reinforcement, single-driver full-range systems, and any build where the goal is maximum bandwidth and sensitivity from one transducer, the B&C 320K/C-A is the 12-inch full-range driver that delivers the complete picture — from the low-mids through the high treble, with the kind of efficiency that makes low-power amplification sound bigger than it has any right to be.
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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.
