FKB108

The MB Quart FKB108 is a pair of 3.5-inch coaxial car speakers built to replace tired factory drivers in door panels, dash locations, rear decks, and pillar pods where space is tight. Each speaker handles 35W RMS and 70W peak, giving the pair 70W RMS and 140W peak, and the 4-ohm impedance works with factory head units and aftermarket amplifiers alike. Frequency response runs 80 Hz to 20 kHz with 88 dB sensitivity, so they play loud and clear even on low-power source units.

A 1-inch aluminum dome tweeter handles the highs, crossed over internally at 6 kHz with a 12 dB slope for a clean handoff from midrange to treble. The thermal-formed polypropylene cone is light enough for quick midrange response, while butyl rubber surrounds add durability and stronger mid-bass. A pure copper voice coil on a Kapton former builds a strong magnetic field and sheds heat, and the over-coil cooling system moves air across the coil through the spider during long sessions at high volume.

Build details matter here. Heavy gauge progressive-die stamped steel frames stay rigid under load, the epoxy-infused natural fiber spider stays flexible without going soft, and a high-temp adhesive keeps the cone and surround bonded through summer heat and winter cold. A textured ABS gasket seals flat against the mounting surface to cut rattle and air leaks. Flexible tinsel leads accept spade connectors or a direct solder joint, so wiring is straightforward on either a factory harness or a new run.

With a 3.41-inch cutout and 1.5-inch mounting depth, the FKB108 fits shallow factory openings in cars, trucks, and SUVs, and it pairs with the rest of the MB Quart Formula line, including Q-Stasis circuitry amplifiers and dual 4-ohm subwoofers, when you are ready to build out a full system.