MD.Lab SW-S12

12″ subwoofer · 4 Ω · 250 W RMS

Fs 39.4 HzQts 0.43Vas 2.06 ft³
The published specs don’t add up:

Recommended box

For a sedan, one sub, 250 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 volume0.85 ft³ (24 L)
Qtc0.80
Fc73 Hz
F3 (−3 dB, no cabin gain)70 Hz
Example box (outside)14 9/16″ × 14 9/16″ × 10 15/16″
Open sealed box in designer

Ported

Net volume2.75 ft³ (78 L)
Tuning (Fb)38 Hz
Portslot 1 9/16 × 14 5/16″, 11 1/4″ long
Port velocity at 250 W63 ft/s
F3 (−3 dB, no cabin gain)36 Hz
Example box (outside)31 1/2″ × 15 3/4″ × 13 11/16″
Open ported box in designer
203040506080100150200667278849096HzdB
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Fs39.4 Hz
Qts0.43
Qes0.521
Qms2.47
Vas2.06 ft³
Re3.8 Ω
Sd≈ 76 in²
Xmax≈ 0.39″
EBP76 — sealed or ported calc.
Sensitivity, 1 W / 1 m90.4 dB calc.

General

Size12″
Voice coils4 Ω
RMS power250 W

Mounting dimensions

Ø12 11/16″cutout Ø11 5/16″mounting depth 3 1/4″magnet Ø≈ 7 3/8″
Cutout diameter11 5/16″
Mounting depth3 1/4″
Overall diameter12 11/16″

“≈” 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 MD.Lab 12″ models