Alpine SWR-1242D (Type-R)

12″ subwoofer · dual 4 Ω · 500 W RMS

Fs 29 HzQts 0.47Vas 1.59 ft³Xmax 0.72″

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 volume0.85 ft³ (24 L)
Qtc0.80
Fc49 Hz
F3 (−3 dB, no cabin gain)47 Hz
Example box (outside)14 3/16″ × 14 3/16″ × 11 9/16″
Open sealed box in designer

Ported

Net volume2.72 ft³ (77 L)
Tuning (Fb)27 Hz
Portslot 1 15/16 × 14 5/16″, 33 5/8″ long
Port velocity at 500 W64 ft/s
F3 (−3 dB, no cabin gain)25 Hz
Example box (outside)31 1/2″ × 15 3/4″ × 15 5/8″
Open ported box in designer
203040506080100150200606672788490HzdB
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Fs29 Hz
Qts0.47
Qes0.5
Qms7.89
Vas1.59 ft³
Re (one coil)3.7 Ω
Sd74.4 in²
Xmax0.72″
Vd53.3 in³ calc.
Mms218 g calc.
BL17.2 T·m calc.
EBP58 — sealed or ported calc.
Sensitivity, 1 W / 1 m85.4 dB calc.

General

Size12″
Voice coilsdual 4 Ω
RMS power500 W

Mounting dimensions

Ø12 5/8″cutout Ø10 13/16″mounting depth 7 11/16″magnet Ø≈ 7 1/16″
Cutout diameter10 13/16″
Mounting depth7 11/16″
Overall diameter12 5/8″

“≈” 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 Alpine 12″ models