SoundQubed 18" HDX4 Series Subwoofers

Product Overview HDX subwoofers build upon the design of the HDC line in response to recent shifts in source material and the mainstream frequency tuning of our customers’ vehicles. Our team scrutinized all aspects of the HDC subs to improve performance at lower frequencies. The resulting HDX dual voice coil competition subwoofer line is more efficient, plays lower, and sounds better setting a new bar for performance and value. INCREASED EXCURSION The new cast basket accommodates larger diameter spiders , providing more room for cone and spider travel. Heat dissipates more quickly with greater movement and a more open airflow path. New spiders with more, higher rolls take advantage of the increased suspension travel. This extra material in the spiders increases the freedom of movement, lowering the Fs, while maintaining durability over time. The subwoofer’s surround profile is higher, reducing material stress while increasing excursion. Cone area and moving mass remain virtually the same, as opposed to inner-tube surrounds popping up here and there. INCREASED STRENGTH AND DURABILITY A fiberglass-reinforced pulp cone meets the strength demands of the increased excursion. A non-press cone formation process increases the cross-section area of the cone walls for more rigidity without adding extra mass. The voice coils feature high-quality, American-made wire and adhesives increasing the thermal working range of the coil. Additionally, thicker, black-anodized aluminum formers increase thermal transfer from the coil wire. The HDX line makes it easier to tune low-frequency pressure into a system without sacrificing impact. HDX subs allow you to explore design choices with high efficiency, making the most of amplifier power and electrical resources. Model HDX412 HDX415 HDX418 RMS Power 2000 W 2000 W 2000 W Peak Power 6000 W 6000 W 6000 W Magnet Weight 403 oz 403 oz 403 oz Coil Diameter 4" 4" 4" Woofer Size 12" 15" 18" F(s) 30.95 Hz 29.61 Hz 22.8 Hz Impedance D1 D1 D1 Z(max) 21.2 Ohms 22.43 Ohms 19.3 Ohms Q(ms) 3.664 4.047 4.568 Q(es) 0.344 0.3658 0.4852 Q(ts) 0.3145 0.3355 0.4386 V(as) 24.93 Liters 55.04 Liters 163.3 Liters L(e) 0.7672 0.8143 2.477 n(0) 0.21% 0.37% 0.38% M(ms) 422 grams 500.3 grams 616.8 grams C(ms) 0.063 0.058 0.078 Sensitivity (1W/1m) 85.22 dB 87.81 dB 87.95dB BL 20.84 21.75 18.4 Xmax 21 21 31 Sd 260.4 mm 323.9 mm 393.7 mm Displacement 0.2³ 0.22³ 0.32³ Mounting Depth 8 5/8" 9 3/8" 11 5/8" Circle Cutout 11 1/2" 13 7/8" 16 9/16" Ported Enclosure (Cu Ft): 1.75-2.75 FT³ 3-6 FT³ 5-7 FT³ Warranty Information SoundQubed warrants all products to be free from defects in materials and workmanship for normal use and service for a period of time not to exceed 12 months for subwoofers, components, earbuds and coaxial and 12 months for amplifiers from the original date of retail purchase. Parts returned must be determined by SoundQubed to be defective prior to any warranty credit or replacement is issued. SoundQubed’s obligation under warranty shall be limited to repairing or replacing, at its discretion, any part proven defective. The customer must prepay transportation charges. Final determination of the suitability of the products for the use contemplated by the buyer is the sole responsibility of the buyer. Warranties are non transferable. Warranty Exclusions Burnt or open coils Customer abuse or competition use and power in excess of rating Amplifiers used in competition or run below rated ohm loads or voltage Improper wiring, including size/gauge, paths, termination method, and series/parallel configuration SoundQubed shall not be liable for any special, direct, indirect, incidental or consequential damages that might be claimed as a result of the failure of any part, including claims for delay, loss of profits, or labor SoundQubed shall not be liable for any damages or injuries to persons or property resulting from improper installation or misuse of any part subject to this warranty THERE ARE NO OTHER WARRANTIES EXPRESSED OR IMPLIED EXTENDING BEYOND THOSE SET FORTH ABOVE Reviews (1 review) Write a Review 1 Review Hide Reviews Show Reviews 5 Hdx4 18 Posted by Matt keith on 02/05/2026 This subwoofer is everything I thought it would be and then some. Very pleased with the design and affordable price for my woofer. Thinking about ordering another one. Great job and great fast delivery