Stereo Integrity Subwoofers and Speakers

How to Choose Stereo Integrity Drivers

Pick the subwoofer by the airspace you can give it, and pick the midbass by the hole your door already has. Everything else follows from those two numbers.

SQL 12 or SQL 15?

Both are rated 1000 W RMS and share the same motor: a 2.75 inch copper coil, a Faraday ring in a Y35 ferrite structure, and dual 8 3/8 inch Nomex spiders. The difference is cone area and box size. The SQL 12 has 82.51 square inches of piston area and wants 0.65 to 1.0 cubic feet sealed or 1.7 cubic feet ported at 27 Hz. The SQL 15 has 127.6 square inches, about 55 percent more, and wants 2 cubic feet sealed or 4.25 cubic feet ported at 22 Hz. If the vehicle can give up 2 cubic feet, the 15 moves more air on the same amplifier. If it cannot, the 12 is the better build.

When does the BM-11 make sense?

When depth is the limit. The BM-11 mounts in 3.09 inches yet keeps 13 mm of one-way Xmax, with a 500 W RMS rating on dual 2 ohm coils that wire to 1 ohm or 4 ohms. Stereo Integrity lists 0.40 cubic feet sealed, within a 0.35 to 0.70 range, and approves it for infinite baffle. It is the SI answer for under-seat and behind-seat truck installs.

TM65 mkIV or TM8 in the doors?

They share the core design: a pure aluminum cone, a 50 mm copper voice coil, 7.9 mm of one-way Xmax, a 150 W RMS rating, and a mounting depth near 58 mm. Choose by the opening. The TM65 mkIV needs a 143 mm cutout and runs best from 65 Hz to 3,500 Hz. The TM8 needs a 183 mm cutout, plays lower with a high-pass above 50 Hz, and crosses at 3,000 Hz in a 2-way. Both carry a higher Qts on purpose, because a door behaves much like an infinite baffle.

Two-way or three-way?

A 2-way pairs a TM midbass with the M28, which Stereo Integrity crosses at 2,000 Hz or higher at 24 dB per octave. A 3-way adds the M350 Carbon from 400 Hz to 5,000 Hz, so the midbass never has to carry vocals. Run active, a 3-way needs six amplifier channels and a DSP to set the crossover points.