Alpine SWR-8D4 (Type-R)

8″ subwoofer · dual 4 Ω · 350 W RMS

Fs 42 HzQts 0.57Vas 0.36 ft³Xmax 0.47″

Recommended box

For a sedan, one sub, 350 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 volume0.35 ft³ (10 L)
Qtc0.81
Fc60 Hz
F3 (−3 dB, no cabin gain)56 Hz
Example box (outside)10 1/4″ × 10 1/4″ × 10 1/16″
Open sealed box in designer

Ported

Net volume1.09 ft³ (31 L)
Tuning (Fb)32 Hz
Port2 round ports Ø2 1/2″, 21 15/16″ long
Port velocity at 350 W110 ft/s
F3 (−3 dB, no cabin gain)28 Hz
Example box (outside)30 1/16″ × 15 3/4″ × 6 7/8″
Open ported box in designer
2030405060801001502006066727884HzdB
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Fs42 Hz
Qts0.57
Qes0.62
Qms6.8
Vas0.36 ft³
Re (one coil)3.7 Ω
Sd31.2 in²
Xmax0.47″
Vd14.7 in³ calc.
Mms80 g calc.
BL11.2 T·m calc.
EBP68 — sealed or ported calc.
Sensitivity, 1 W / 1 m82.9 dB calc.

General

Size8″
Voice coilsdual 4 Ω
RMS power350 W

Mounting dimensions

Ø8 7/16″cutout Ø6 7/8″mounting depth 4 1/2″magnet Ø≈ 4 1/2″
Cutout diameter6 7/8″
Mounting depth4 1/2″
Overall diameter8 7/16″

“≈” 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 Alpine 8″ models