18 Sound 6NTLW2000 – Ultra-Compact 6.5-Inch Neodymium Woofer with Dual Gap Motor and 320 Watt Power Handling
The 18 Sound 6NTLW2000 is the smallest dual-gap driver in 18 Sound’s product range — bringing the same Tetracoil motor architecture found on the 10NTLW2000 and 10NTLS2000 down to a 6.5-inch frame that weighs just 1.2 kg. With a 51 mm dual voice coil operating in the same 8.5 mm dual magnetic gap as the 10-inch Tetracoil drivers, 320 W AES / 600 W continuous program power handling, a 75 Hz – 8000 Hz bandwidth, and the lowest inductance of any LF driver in 18 Sound’s catalogue at 0.22 mH, the 18 Sound 6NTLW2000 delivers dual-gap motor technology and power handling that would be remarkable from an 8-inch driver — from a 6.5-inch platform that weighs the same as the basic 5W430.
The 320 W AES from a 6.5-inch driver is the headline. Most professional 6.5-inch woofers handle 100–200 W. The 18 Sound 6NTLW2000 handles 320 W — approaching the 10NTLW2000’s 350 W from a driver that is four inches smaller in diameter and 700 g lighter. The dual-gap motor’s doubled thermal dissipation is the mechanism: the 51 mm coil operates in two magnetic gaps, exposing twice the coil surface to the magnetic field for heat exchange that is twice as efficient as a single-gap design. The same thermal principle that makes the 10-inch Tetracoil drivers handle 350 W scales down to the 6.5-inch format with proportionally spectacular results.
The 0.22 mH inductance is the specification that engineers will notice first. It’s the lowest of any LF driver in 18 Sound’s entire range — lower than the 10NTLW2500’s 0.45 mH, lower than the 10NCX750’s 0.54 mH, lower than the 5W430’s 0.49 mH. The dual-gap motor’s inductance linearisation produces an impedance curve that is flatter than most compression drivers. The practical consequence is the 8000 Hz bandwidth — the 18 Sound 6NTLW2000 produces controlled output from 75 Hz through the entire mid-range and into the lower treble with minimal impedance rise affecting the response.
At 1.2 kg with a 162 mm overall diameter, 148 mm baffle cutout, 108 mm depth, and a 3.5-litre recommended enclosure tuned to 85 Hz, the 18 Sound 6NTLW2000 is designed for ultra-compact line arrays and multi-way systems where the driver needs to deliver maximum power handling from minimum size and weight. Available in 8 and 16 Ω.
Design and Construction of the 18 Sound 6NTLW2000
The 18 Sound 6NTLW2000 uses a 51 mm (2-inch) aluminium dual voice coil operating in a neodymium dual-gap motor assembly. The motor is the defining technology — the same Tetracoil dual-gap concept used on the 10NTLW2000 and 10NTLS2000, scaled to the smallest format 18 Sound offers it in.
The 51 mm coil diameter matches the 10NTLW2000’s coil — the same coil platform in a driver with 57% less cone area. The 14 mm winding depth operates in the same 8.5 mm dual magnetic gap found on both 10-inch Tetracoil drivers. The dual gap doubles the coil surface exposed to the magnetic field at any given position, producing the doubled thermal dissipation that sustains the 320 W AES / 600 W program power rating from a 6.5-inch format.
The 11.6 Tm force factor driving 19 g of moving mass produces 93 dB sensitivity. The 19 g Mms and the dual-gap motor’s Bl symmetry combine to deliver what 18 Sound describes as the lowest intermodulation distortion in the professional market — the same claim made for the 10-inch Tetracoil drivers. The balanced Bl shape maintains consistent force output across the excursion range, keeping even-order harmonic distortion and intermodulation products measurably lower than single-gap alternatives.
The inductance linearisation from the dual-gap architecture produces the extraordinary 0.22 mH Le. In a conventional single-gap motor, the voice coil’s inductance changes as the coil moves in and out of the gap — producing impedance modulation that distorts the response at higher frequencies. The dual-gap motor’s symmetrical magnetic circuit linearises the inductance, keeping it consistent across the excursion range. The result is the flattest impedance behaviour and the widest bandwidth of any 18 Sound LF driver format — the 0.22 mH is what makes 8000 Hz output possible from a 6.5-inch woofer.
The 4.9 mm Xmax with 7.5 mm Xvar provides displacement capability that is strong for the 6.5-inch format. The 7.5 mm Xvar is particularly notable — 53% more displacement beyond the linear limit before mechanical limits are reached. For transient peaks that push beyond the 4.9 mm linear range, the 7.5 mm Xvar provides substantial headroom.
The curvilinear cone uses 18 Sound’s high-damping composition. The M-roll surround provides ultra-linear excursion control — 18 Sound describes the balance between the motor and the suspension as allowing both very high excursion and extreme precision in the mid band. The weather-protected treatment provides outdoor durability.
At 1.2 kg, the 18 Sound 6NTLW2000 matches the 5W430’s weight — despite carrying a 51 mm dual voice coil, a neodymium dual-gap motor, and handling four times the power (320 vs 80 W AES). The neodymium motor is the weight enabler — ferrite at this performance level would weigh substantially more. The 162 mm overall diameter, 148 mm baffle cutout, 108 mm depth, and 14 mm flange provide a standard 6.5-inch mounting interface.
Performance and Applications for the 18 Sound 6NTLW2000
The 18 Sound 6NTLW2000 delivers 93 dB sensitivity across a 75 Hz – 8000 Hz bandwidth. The 93 dB is competitive for a 6.5-inch driver with a dual-gap motor — the heavier motor assembly and coil contribute to a Mms that is higher than basic 6.5-inch drivers, but the 11.6 Tm Bl compensates with strong motor authority.
The 8000 Hz bandwidth matches the 5W430 — but the 18 Sound 6NTLW2000 achieves it through dual-gap inductance linearisation rather than through a lightweight simple coil. The 0.22 mH Le keeps the impedance curve flat enough for the response to extend smoothly to 8 kHz without the inductive rolloff that drivers with higher inductance exhibit in the upper mid-range.
In compact line array elements, the 18 Sound 6NTLW2000 handles the full mid-bass and mid-range frequency range — 75 Hz through 8000 Hz — from a single 6.5-inch driver. Multiple drivers per element produce the combined output that line arrays require, and the 16 Ω variant allows multi-driver parallel and series-parallel configurations.
The 320 W AES power handling means each 6.5-inch element can accept sustained amplifier power that would destroy most drivers in this format. For line arrays where each element runs at or near full power for hours, the dual-gap thermal dissipation keeps the 18 Sound 6NTLW2000 operating within its thermal limits while lighter-coil alternatives would have failed.
18 Sound recommends a 3.5-litre (0.12 ft³) vented enclosure tuned to 85 Hz. Three and a half litres is an extraordinarily compact cabinet — small enough to fit inside the narrowest line array elements and the most compact multi-way enclosures. The 0.35 Qts and 226 Hz EBP sit on the sealed/vented boundary, though the high EBP and 86 Hz Fs confirm the 18 Sound 6NTLW2000 delivers its best performance in vented enclosures where the motor’s control keeps the bass tight and defined.
The comparison to the 10NTLW2000 illustrates how the Tetracoil technology scales. Both use 51 mm coils in 8.5 mm dual gaps. The 10NTLW2000 produces 98.5 dB sensitivity with 38 g Mms from 260 mm of cone. The 18 Sound 6NTLW2000 produces 93 dB with 19 g Mms from 152 mm of cone. The 10-inch version has 2.6 times more cone area and 5.5 dB more sensitivity. But the 6.5-inch version weighs 37% less (1.2 vs 1.9 kg), reaches 3 kHz higher (8000 vs 5000 Hz), produces 65% lower inductance (0.22 vs 0.63 mH), and fits a 3.5-litre enclosure versus the 10-inch’s 14 litres.
The dual-gap distortion advantage is most significant at high power. At moderate levels, the difference between single-gap and dual-gap distortion is subtle. At 200+ watts — where the coil is swinging through significant excursion while reproducing complex multi-frequency content — the 18 Sound 6NTLW2000’s symmetrical Bl keeps the output clean. Vocals stay natural. Transients stay defined. The mid-range maintains clarity instead of becoming muddy as power increases.
Conclusion – 18 Sound 6NTLW2000 Woofer
The 18 Sound 6NTLW2000 is the smallest dual-gap driver in 18 Sound’s range — and it carries every benefit of the Tetracoil motor architecture down to a 6.5-inch platform that weighs 1.2 kg. The 320 W AES power handling is four times what the similarly weighted 5W430 achieves. The 0.22 mH inductance is the lowest of any LF driver in the catalogue. The 8000 Hz bandwidth reaches into the lower treble. The 3.5-litre enclosure is the most compact recommended volume of any 18 Sound woofer.
The dual-gap motor’s doubled thermal dissipation, Bl symmetry, and inductance linearisation are the technologies that make these specifications possible. The same engineering principles that power the 10-inch Tetracoil flagships produce proportionally spectacular results at 6.5 inches — 320 watts, 0.22 millihenries, 8 kilohertz, 1.2 kilograms.
For ultra-compact line arrays, compact multi-way systems, and any application where a 6.5-inch driver needs to deliver maximum power handling with the lowest distortion and widest bandwidth from the smallest possible enclosure, the 18 Sound 6NTLW2000 is the dual-gap 6.5-inch that brings Tetracoil technology to the format where it matters most. Every watt is handled, every frequency is reached, and it weighs 1.2 kg.
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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.
