Kicx ST-12M (2+2)

12″ subwoofer · dual 2 Ω · 500 W RMS

Fs 39.5 HzQts 0.70Vas 1.04 ft³
The published specs don’t add up:

Recommended box

For a sedan, one sub, 500 W. It’s the same math as the designer’s step-by-step mode, where you can fit the box to your space, vehicle and amp and get plans, a cut sheet and DXF.

Sealed

Net volume1.80 ft³ (51 L)
Qtc0.88
Fc50 Hz
F3 (−3 dB, no cabin gain)43 Hz
Example box (outside)31 1/2″ × 15 3/4″ × 9 1/16″
Open sealed box in designer

Ported

Net volume3.07 ft³ (87 L)
Tuning (Fb)32 Hz
Portslot 2 3/8 × 14 5/16″, 23 15/16″ long
Port velocity at 500 W62 ft/s
F3 (−3 dB, no cabin gain)27 Hz
Example box (outside)31 1/2″ × 15 3/4″ × 16 7/16″
Open ported box in designer
203040506080100150200606672788490HzdB
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Fs39.5 Hz
Qts0.70
Qes0.8
Qms5.55
Vas1.04 ft³
Re (one coil)1.8 Ω
Sd79.1 in²
Xmax≈ 0.39″
Mms203 g calc.
BL10.6 T·m calc.
EBP49 — suits sealed calc.
Sensitivity, 1 W / 1 m85.6 dB calc.

General

Size12″
Voice coilsdual 2 Ω
RMS power500 W

Mounting dimensions

Ø≈ 12 1/2″cutout Ø11 5/16″mounting depth 5 15/16″magnet Ø≈ 7 3/8″
Cutout diameter11 5/16″
Mounting depth5 15/16″

“≈” means the value isn’t in the spec sheet and a typical value for the size is used; “calc.” means it’s calculated from the published parameters. Check the manufacturer’s spec sheet before you build.

Data sources

Other Kicx 12″ models