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The limited edition MT 4X4 Series of Fi subwoofers is designed to meet the needs of the serious competitor and and monster basshead. Starting with four ultra-high grade Y35 magnets, a flux flow derived back plate geometry, and a solid pole with aluminum sleeve, inner heatsink, and aluminum compression cap, and the famed Omega Coil, there is plenty of thermal capacity in the MT 4x4 Series.  A massive 4″ voicecoil for increase thermal capacity, we designed the rest of the motor via FEA to optimize the proprietary US steel (water jet and machined in house at Fi when your order is placed). Our Fi designed heavy 5 spider pack coupled with our special 144 tinsel count leadwire to keep the moving assembly under control at extreme excursion levels. The reworked surround geometry on the 12″, 15″, and 18″ models optimizes cone area vs excursion yielding the most output vs excursion. With the MT4x4 we have also utilized the ultra high temp and strength epoxy that we use only on the 4.11.  The MT4x4 Series is designed for competition use and monster daily driving systems requiring high linearity and extreme power handling. From a punishing low end to the subtle nuances in your favorite reference track, the  MT4x4 Series delivers!



  • Dual 1 and Dual 2 Ohm

  • 4 stack of Y35 10" magnets

  • Extra heavy aluminum basket

  • Wrap around gasket

  • Kraft pulp fiber reinforced cone

  • Dual layer wide foam surround

  • Standard heavy duty stitched hybrid lead or push/hybrid termination

  • 144 tinsel count leads

  • FEA optimized motor

  • 4500W

  • Triple inductance/cooling aluminum rings

  • 4” diameter 4 layer Omega coil

  • 10″ Progressive spiders (5)

  • Water jet and machined in house at Fi

  • Ultra temp and strength epoxy

  • 33mm Xmax

  • 12″, 15″, and 18″sizes


PriceFrom $729.00
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