High-performance ferrite external magnetic magnetic circuit structure, high-power AL voice coil skeleton and high temperature resistant SV line voice coil, with high power. High-strength reinforced iron basin frame and ultra-long stroke linear displacement design, large dynamic range, low low-frequency distortion. The tone is sweet and delicate. It is suitable for low-mid frequency units in household Hi-Fi two-way phase inverted bookshelf speakers, and also suitable for low-frequency units in three-way phase inverted floor-standing speaker systems.