RS Speakers W 140.38 Fibonacci 5.5" woofer

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The RS Speakers W 140.38 Fibonacci bass-midrange driver is a high-quality 5.5-inch driver that combines innovative Italian engineering with patented technologies to deliver exceptional sound quality. Featuring a unique, custom-designed paper cone in the Fibonacci pattern, this woofer is designed for audiophiles seeking clarity, low distortion, and a pure listening experience. Its advanced construction includes a double asymmetric rubber surround, a progressive Conex spider, and a powerful ferrite magnet circuit, making it the ideal choice for high-end home audio systems and demanding DIY speaker projects.

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Highlights

• Patented “Fibonacci” paper membrane for reduced resonances and increased stiffness
• Double surface damping for balanced stiffness and damping
• 1.5" voice coil on fiberglass former for high thermal load capacity
• Ferrite magnetic circuit with aluminum equalization ring for low distortion
• Includes sealing gasket, mounting screws and thumb nuts for easy installation.

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Product details RS Speakers W 140.38 Fibonacci

RS Speakers W 140.38 Fibonacci 5.5" woofer 8 ohms

The heart of the W 140.38 Fibonacci is its meticulously engineered diaphragm, which features a custom-designed para-elliptical profile and a laser-engraved Fibonacci pattern. This innovative design, inspired by the Golden Ratio, minimizes unwanted resonance modes and selectively increases the diaphragm's rigidity. The result is a remarkably clean and natural sound signature that makes this woofer stand out in the loudspeaker category for both home audio enthusiasts and professional developers.

Performance is further enhanced by the woofer's dual surface damping, which creates a "sandwich" structure with acrylic and damping layers. This approach strikes a balance between rigidity and internal damping, effectively controlling cone breakup and unwanted coloration. The specially designed NBR butyl rubber surround utilizes Double Asymmetric Rolls technology, ensuring symmetrical and linear excursion even at high levels. Combined with a progressive Conex spider, the mechanical design supports large excursions while maintaining precise control.

At the heart of the driver unit is the 1.5-inch voice coil wound on a fiberglass former, ensuring excellent mechanical stability and heat resistance in demanding applications. The ferrite magnet circuit incorporates an aluminum equalization ring, which significantly reduces coil inductance and harmonic distortion. Ventilation for the magnet and voice coil helps minimize power losses and ensures consistent performance even under high load. With an efficiency of 86.2 dB at 1W/1m and a power handling of 120W AES (240W program), the W 140.38 Fibonacci is ready to excel in a wide range of woofer and mid-bass applications.

Designed for maximum flexibility, this woofer is ideal for use in custom-built speaker systems, high-end home audio setups, or ambitious DIY speaker kit projects. Thoughtful mounting features, such as an open basket with thin struts to minimize back reflections, along with the included gasket, mounting screws, and thumb nuts, make installation easy. Whether you're upgrading an existing system or building from scratch, the RS Speakers W 140.38 Fibonacci delivers uncompromising performance and sonic purity.

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Specifications

• Article number: W 140.38 Fibonacci
• woofer series Fibonacci
• woofer type Woofer
• Nominal diameter 5.5" | 140 mm
• Resilience (QMW) 120W
• Continuous Program Power 240W
• Impedance (Z) 8 Ω
• Sensitivity (SPL at 1m / 2.83V) 86.2 dB
• Voice coil diameter 38 mm
• Weight magnet 515 g
• DC resistance (Re) 5.1 Ω
• Voice coil induction (Le) 0.68 mH
• Resonance frequency (Fs) 46.6 Hz
• Mechanical quality (Qms) 4.65
• Electrical quality factor (Qes) 0.45
• Total quality (Qts) 0.41
• Moving mass (mms) 13.8 g
• Suspension compliance (Cms) 854 µm/N
• Membrane area (Sd) 78.5 cm²
• Force factor (BL) 6.80 Tm
• Equivalent volume (Vas) 7.4 L
• Maximum displacement (Xmax) 5.0 mm
• Cone / Diaphragm Material paper
• Bead material Rubber
• Voice coil wire material Copper
• Voice coil mold material Fiberglass
• Basket/frame material Aluminum die-cast
• Magnetic material Ferrite
• Outer diameter 148 mm
• Total depth 72 mm
• Cutout diameter 113 mm
• Bolt Circle Diameter 138 mm
• Mounting holes 6
• Mounting hole diameter 4.2 mm
• Bass reflex volume 9 L
• Bass reflex F3 45 Hz