SA-18 V.2 D2

The SA-18 V.2 D2 is an 18-inch car subwoofer rated at 1250W RMS and 2500W peak with dual 2-ohm coils. The v.2 generation is a full redesign of the original SA platform, and the centerpiece is a 2.75-inch aluminum voice coil former that handles the power of larger 3-inch coils while keeping moving mass down and allowing a wider spider for better control.

Mass, motor force, and suspension stiffness are matched to the 1250W rating rather than a headline number. A large magnet shorting ring cuts distortion for a more even response across the bass range, and the 18-inch model uses a larger 8.66-inch motor to move the heavier cone. A multi-layer spider, doubled-up stitched XL tinsel leads, a competition-grade paper cone, foam surround, and cast aluminum frame handle the mechanical load. There is 19mm of one-way linear excursion and a 37mm mechanical limit before the coil bottoms.

At 90.1 dB sensitivity and a 29 Hz free-air resonance, this sub goes low without needing a huge amplifier. Sundown recommends 4.5 cu ft ported with 66 sq in of port tuned to 35 Hz for maximum output, or 3.5 cu ft sealed for a tighter, more controlled sound in a daily vehicle. Bandpass builders can run a 2.25 cu ft sealed side with a 6.75 cu ft ported side.

Mounting depth is 10.125 inches with a 16.69-inch cutout, which suits van, SUV, truck, and wall builds.