18 Sound 15NCX750 – Lightweight 15-Inch Neodymium Coaxial with ISV Voice Coil and 4.9 kg Total Weight
The 18 Sound 15NCX750 is the lightest 15-inch coaxial transducer in 18 Sound’s range. At 4.9 kg — 1.6 kg lighter than the 15NCX910BE and 3.6 kg lighter than the 15NCX1000 — the 18 Sound 15NCX750 delivers true coaxial point-source output from a package that weighs less than many standalone 15-inch woofers. With 98 dB LF sensitivity, 107.5 dB HF sensitivity, a 75 mm ISV voice coil on the woofer, a titanium HF diaphragm on a 64 mm EWAL compression driver, 80° conical dispersion, and a dedicated passive crossover available from 18 Sound, the 18 Sound 15NCX750 is the most accessible and most compact 15-inch coaxial in the range.
The 4.9 kg weight is the headline. A complete two-way coaxial point source — woofer, compression driver, shared neodymium motor, phase plug, integrated waveguide — at 4.9 kg. That’s lighter than B&C’s standalone 10BG76 sub driver (4.85 kg is close but the 15NCX750 delivers a complete two-way system). For stage monitors, compact main PA, and portable speaker systems where every gram of driver weight affects cabinet weight, transport logistics, and rigging calculations, the 18 Sound 15NCX750’s weight advantage over the other 15-inch coaxials is transformative.
The 0.37 Qts is the most versatile alignment of any 18 Sound 15-inch coaxial. Where the 15NCX910BE’s 0.33 and the 15NCX1000’s 0.31 favour vented enclosures, the 18 Sound 15NCX750’s 0.37 sits on the sealed/vented boundary — giving builders genuine flexibility to design either enclosure topology. Sealed for tighter, more controlled bass. Vented for more extension and output. The driver works well in both.
The dedicated passive crossover — the XO15NCX — makes the 18 Sound 15NCX750 a ready-to-use transducer system. Builders who don’t want to design their own crossover network can use 18 Sound’s factory-designed filter with a 24 dB/oct low-pass and 12 dB/oct high-pass. For DIY builders and small-scale manufacturers, this removes one of the most complex steps in speaker system design.
At 185 mm depth — 20 mm shallower than the 15NCX910BE and 12 mm shallower than the 15NCX1000 — the 18 Sound 15NCX750 fits the shallowest 15-inch cabinet designs. Combined with the 4.9 kg weight and 80° conical dispersion, it’s the 15-inch coaxial that demands the least from the cabinet in every dimension.
Design and Construction of the 18 Sound 15NCX750
The 18 Sound 15NCX750 integrates a two-way transducer system into a single chassis powered by a single neodymium magnet motor.
The LF section uses a 75 mm (3-inch) copper ISV (Interleaved Sandwich Voice Coil) — the same coil technology and diameter as the 15NCX910BE. The ISV architecture places conductor on both inner and outer surfaces of the former, creating the mass-balanced coil that produces linear motor behaviour. The copper winding provides the thermal conductivity that sustains the 400 W AES / 800 W program power rating.
An aluminium demodulating ring (SDR) in the LF magnetic circuit reduces flux modulation during excursion. The SDR flattens LF impedance and phase with constant power transfer, reducing harmonic distortion at higher excursion levels. The combination of ISV and SDR produces clean, low-distortion bass output — the same distortion reduction approach used across all three 18 Sound 15-inch coaxials.
The 18.4 Tm force factor driving the 81 g moving mass produces 98 dB sensitivity and 4.5% reference efficiency. The 81 g Mms is the lightest of any 18 Sound 15-inch coaxial LF section — 5 g lighter than the 15NCX910BE’s 86 g and 29 g lighter than the 15NCX1000’s 110 g. The lighter moving mass contributes to the higher sensitivity relative to the power handling — the 18 Sound 15NCX750 produces more output per watt than the 15NCX1000’s 96 dB despite handling less total power.
The 49 Hz Fs is the lowest of any 18 Sound 15-inch coaxial — 4 Hz below the 15NCX1000’s 53 Hz and 6 Hz below the 15NCX910BE’s 55 Hz. The lower Fs combined with the 0.37 Qts and 122 Hz EBP define a driver with the most versatile enclosure alignment in the coaxial range. The EBP of 122 Hz sits right on the sealed/vented boundary — builders can design a sealed cabinet for tighter transient response or a vented cabinet for more bass extension without compromising the driver’s performance in either topology.
The curvilinear paper cone uses 18 Sound’s high-damping pulp composition, providing smooth response within the LF operating range. The water-repellent treatment provides outdoor durability. The 5.5 mm Xmax is the shortest of the three 15-inch coaxials (7 mm on 15NCX910BE, 7.5 mm on 15NCX1000) — the trade-off for the lighter moving mass and higher sensitivity.
The HF section uses a 64 mm (2.5-inch) EWAL (Edge-Wound Aluminium) voice coil driving a titanium diaphragm with a proprietary hybrid radial tangerine phase plug — 18 Sound’s 3P (Proprietary Phase Plug) architecture. The 64 mm HF coil is smaller than the 15NCX910BE’s 75 mm and the 15NCX1000’s 100 mm — contributing to the lighter total weight while providing the 107.5 dB HF sensitivity and 70 W AES power handling that compact two-way systems require.
The 3P radial tangerine phase plug is a specific HF architecture that 18 Sound highlights as producing smooth, coherent wavefronts across the entire HF operating range with high manufacturing consistency. The tangerine-style plug uses multiple radial slots — shaped like the segments of a tangerine — to divide the wavefront into segments that recombine at the exit with controlled phase behaviour. The short openings and high flare rate of the 3P design keep distortion low while maximising mid-high frequency output.
The titanium diaphragm is joined to a high-strength, high-temperature treated Nomex voice coil former at its upper bend edge. The bent edge joint provides extended frequency energy transfer and improved linearity compared to a straight former joint — the same construction used on the 15NCX1000.
A copper sleeve on the HF pole piece reduces inductance above 10 kHz, improving phase and impedance linearisation in the upper treble. A specific HF exit profile maximises coupling between the compression driver output and the woofer cone’s profile, shaping the combined 80° conical dispersion.
The single neodymium magnet motor powers both sections from a compact assembly that keeps total weight to 4.9 kg. The single-motor architecture is the primary weight saving — one magnet instead of two means less magnetic material, less steel, and less total mass.
At 4.9 kg, 393 mm overall diameter, 360 mm baffle cutout, and 185 mm depth, the 18 Sound 15NCX750 is the most compact and lightest 15-inch coaxial in 18 Sound’s range. The 14 mm flange thickness provides a secure mounting interface.
Performance and Applications for the 18 Sound 15NCX750
The 18 Sound 15NCX750 delivers 98 dB LF sensitivity from 55 Hz to 4500 Hz and 107.5 dB HF sensitivity from the 1.2 kHz crossover point upward. The 9.5 dB sensitivity difference between sections is managed through the crossover network — the HF section is padded to match the LF output level.
The 80° conical dispersion provides uniform coverage in both horizontal and vertical planes from a single point source. The conical pattern is the inherent advantage of coaxial architecture — the same coverage angle in every direction. For stage monitors, where the performer needs consistent coverage regardless of position relative to the wedge, and for compact main PA, where the audience occupies multiple angles relative to the cabinet, the conical dispersion ensures uniform tonal balance across the entire coverage area.
The 400 W AES / 800 W program LF power handling is the lowest of the three 18 Sound 15-inch coaxials (450 W for 15NCX910BE, 600 W for 15NCX1000). For compact PA tops and stage monitors operating at moderate to high power levels, 400 W AES provides adequate headroom. The 98 dB LF sensitivity means less amplifier power is needed to reach a given SPL compared to the 15NCX1000’s 96 dB — the higher efficiency partially compensates for the lower absolute power handling.
The 0.66 mH LF inductance is the lowest of any 18 Sound 15-inch coaxial — lower than the 15NCX910BE’s 1.1 mH and the 15NCX1000’s 1.4 mH. The low inductance produces flatter impedance behaviour in the upper LF range and smoother crossover transitions in both passive and active designs.
18 Sound recommends enclosures from 80 litres for the 18 Sound 15NCX750. The 0.37 Qts and 122 Hz EBP give builders the flexibility to choose sealed or vented alignments. Sealed enclosures in the 50–80 litre range produce tight, well-controlled bass with a natural rolloff below the driver’s resonance. Vented enclosures from 80 litres with appropriate tuning extend the bass response and increase output below 80 Hz.
The dedicated XO15NCX passive crossover is the feature that makes the 18 Sound 15NCX750 the most builder-friendly coaxial in the range. The factory-designed crossover uses a 24 dB/oct Linkwitz-Riley low-pass and a 12 dB/oct high-pass filter, providing a complete, tested crossover solution that eliminates the need for custom crossover design. For DIY builders, small manufacturers, and installers who want a ready-to-use coaxial system, the XO15NCX turns the 18 Sound 15NCX750 into a drop-in solution — connect the crossover, wire the amplifier, and the system is complete.
The 4500 Hz upper LF bandwidth is the widest of any 18 Sound 15-inch coaxial — 500 Hz wider than the 15NCX910BE’s 4000 Hz and 900 Hz wider than the 15NCX1000’s 3600 Hz. The wider LF bandwidth provides more overlap with the HF section through the crossover region, supporting smoother transitions with gentler filter slopes.
The choice across 18 Sound’s three 15-inch coaxials is clear. The 15NCX1000 delivers maximum power (600 W AES), widest dispersion (90°), and the lowest crossover (1.0 kHz) — the maximum-output option at 8.5 kg. The 15NCX910BE delivers the highest LF sensitivity (99.5 dB), beryllium HF quality, and premium distortion performance — the high-fidelity option at 6.5 kg. The 18 Sound 15NCX750 delivers the lightest weight (4.9 kg), shallowest depth (185 mm), most versatile enclosure alignment (0.37 Qts), lowest inductance (0.66 mH), widest LF bandwidth (4500 Hz), and a dedicated passive crossover — the most accessible, most compact option in the range.
Conclusion – 18 Sound 15NCX750 Coaxial Driver
The 18 Sound 15NCX750 is the entry point to 18 Sound’s 15-inch coaxial range — and “entry point” doesn’t mean compromise. The 75 mm ISV copper LF coil, SDR distortion reduction, EWAL titanium compression driver with 3P tangerine phase plug, and single neodymium motor deliver genuine professional coaxial performance from a 4.9 kg package that is lighter than many standalone woofers.
The 4.9 kg weight, 185 mm depth, 0.37 Qts enclosure flexibility, and available XO15NCX passive crossover make the 18 Sound 15NCX750 the most practical 15-inch coaxial for builders who want point-source coherence without the complexity of custom crossover design or the weight of larger-coil alternatives. It’s a complete two-way point source that weighs less than five kilograms — ready to use with the factory crossover or ready to integrate into a custom active system.
The 400 W AES LF and 70 W AES HF power handling are the trade-offs for the lighter weight. For high-power touring applications demanding 600 W, the 15NCX1000 is the right choice. For beryllium HF quality, the 15NCX910BE is the right choice. For the lightest, shallowest, most versatile, most builder-friendly 15-inch coaxial point source in 18 Sound’s range, the 18 Sound 15NCX750 is the driver that makes coaxial technology accessible. Four point nine kilograms, 80° conical, ISV and SDR, ready-to-use crossover available — the lightest 15-inch coaxial in the catalogue.
VIEW MORE 18 Sound PRODUCTS HERE.
About 18 Sound
18 Sound products are proudly made in Reggio Emilia, Italy, combining advanced technology with Italian craftsmanship. Known for their high-performance professional audio components, 18 Sound is a trusted name in the global audio industry. Their state-of-the-art manufacturing and strict quality control ensure exceptional reliability and sound clarity. 18 Sound products are designed to meet the demands of speaker builders and audio professionals, 18 Sound offers premium products with outstanding value and performance worldwide.
