Sky High Car Audio FMX Series 18" Subwoofer

Sky High Car Audio FMX Series Subwoofers

Available in 6.5” – 18” (excludes 10”)

D1/D2 Ohm Options

FMX: Forged to Perform. Built to Endure. 

The FMX Series from Sky High Car Audio is the next evolution of our commitment to high-output, thermally superior yet efficient subwoofers for serious bass enthusiasts. With decades of experience, competitive insight, and

our long standing pursuit of big bass, the FMX Series builds upon our legacy by pushing limits. This isn’t just a bigger sub—it’s a smarter, stronger design for those who demand more from their system. 

At the heart of the FMX Series lies a massive 3.5” 8 layer high-temp voice coil, the centerpiece of its performance. This coil not only allows for top-tier excursion of 37mm and xmech at 44mm, but it increases thermal handling by over 50% compared to standard 3” designs—without sacrificing the efficiency that makes Sky High subs musical, responsive, and versatile. The result is a woofer that thrives in high-output builds while staying cool and controlled.

Rated at 3500W RMS, the FMX Series is designed for sustained musical power. A quad-stacked 220mm Y35 ferrite motor generates brutal magnetic force. The motor features also include an aluminum shorting ring, pole vents and (4) drilled and tapped backplate holes, giving builders flexibility for reinforced mounting or enhanced cooling. A full-size 10” progressive spider pack provides long-lasting mechanical control and suspension stability—key for subs built to dig deep and hit hard. 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 FMX Series is all business. Each woofer features our signature forged carbon fiber dust cap, nested into a tooled recess for added cone strength. A fiberglass-reinforced cone support, precision-molded foam surround, and our tooled SHCA magnet boot complete the package in a clean, all-black finish that matches its serious performance. 

Connection points include 4ga push terminals designed to handle real-world current without compromise. Like all SHCA subwoofers, the FMX is designed for low FS and high BL, delivering powerful, wideband bass—not just a single-note boom.

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-FMX-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. 

Welcome to the next tier of performance.

Welcome to the Sky High Car Audio Revolution.