Sky High Car Audio FXXL Series 18" Subwoofer

Sky High Car Audio FXXL Series Subwoofers

Available in 12” – 18” | D1/D2 Ohm Options 

Our Ferrite Flagship. 

Purpose Built to Punish.

The FXXL Series from Sky High Car Audio is the peak of subwoofer engineering—our no-compromise solution for those who demand maximum output, precision control, and true competition-grade performance. Backed by years of technical experience and hands-on development across multiple high-performance audio brands, the FXXL Series reflects the very best of everything we’ve learned in one elite platform.

At the core of the FXXL Series is a massive 4” 8 layer high-temp voice coil, engineered for power handling and consistent output under extreme demand. Rated at 5000W RMS, this coil provides increased surface area and thermal mass, resulting in cooler operation and significantly more headroom than even our FMX series. The FXXL series bridges the gap between SPL monsters and daily drivability.

Driving that power is a towering quad-stacked 9.96” (253mm) Y35 ferrite motor structure, is packed with features like an aluminum shorting ring, pole vents and (4) drilled and tapped backplate holes, giving builders flexibility for reinforced mounting or enhanced cooling. Our motor design results in maximum airflow and heat dissipation during high-output demos.

Mechanically, the FXXL uses a full 10” progressive spider pack paired with a fiberglass cone support and a hardened paper cone. The cone is tooled with a recessed cavity to seat the standard forged carbon fiber dust cap, increasing structural integrity at peak excursion. The surround is precision-molded foam, delivering control, compliance, and longevity across extreme stroke conditions. To round out the features we utilize a secondary pressure cap nestled under the primary cap which works as a pressure buffer and structural reinforcement to the primary cap.  

Aesthetically, the FXXL Series carries the Sky High signature stealth look—all black with a carbon dust cap, tooled SHCA magnet boot, and oversized push terminals to ensure secure, high-current connectivity. Every design detail, from the cone geometry to the airflow path, was made to maximize both performance and reliability.

Engineered with low FS and high BL, the FXXL plays strong across the entire bass frequency spectrum with precision, power, and musicality…is that a word? Anyways…It’s not just about being loud—it’s about being the best at every level.

Box Designs: Sky High Car Audio is proud to partner with Hunter Martin from EZ DB’s, one of the most respected and proven enclosure designers in the industry. We’ll be offering FREE box designs—including ported, 4th order, and 6th order options where applicable—tailored specifically for our subwoofers to ensure maximum performance and reliability. As a bonus, any customer who purchases 4 or more BMX, FMX, or FXXL series subwoofers directly from Sky High Car Audio will receive a $50 credit toward a custom enclosure design from EZ DB’s, giving you a serious head start on a professionally designed, competition-ready subwoofer enclosure. Every SHCA subwoofer is tested using DATS-LA, measured with the backplate off the surface after full break-in, ensuring accurate and trustworthy TS data. 

SHCA-FXXL-18 Enclosure Designs

Customization Options: Sky High Car Audio is proud to offer in-house custom build options for select subwoofer lines, hand-assembled at our Sparks, NV facility. Customization is available exclusively on the BMX Series 10–18”, FMX Series 12–18”, and FXXL Series 12–18” models. We offer custom Prismatic Powders powder coating in single-stage or two-stage finishes to match your build’s aesthetic (additional cost and lead time apply). For those looking to stand out in the lanes or the show floor, forged carbon fiber cone upgrades are available on FMX and FXXL subs for a premium finish and added cone rigidity. Builders can choose between direct leads (with length and color options) or push terminals on FMX and FXXL models, which come standard with direct leads. We also offer box support add-ons for our threaded backplates and optional back plate cooling modifications for all eligible series (back plate cooling to drop 1/1/26). Lastly we can build you a custom spider pack to meet your needs, but for daily music we highly suggest the stock build form for suspension. 

FXXL: Purpose Built to Punish

Welcome to the Sky High Car Audio Revolution.