Rockford Fosgate Punch P3SD4-8 (Shallow)

8″ subwoofer · dual 4 Ω · 150 W RMS

Fs 39 HzQts 0.87Vas 0.56 ft³Xmax 0.33″

Recommended box

For a sedan, one sub, 150 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 volume0.78 ft³ (22 L)
Qtc1.14
Fc51 Hz
F3 (−3 dB, no cabin gain)39 Hz
Example box (outside)10 1/4″ × 10 1/4″ × 19 7/16″
Open sealed box in designer

Ported

Net volume1.31 ft³ (37 L)
Tuning (Fb)36 Hz
Portslot 1 9/16 × 14 5/16″, 31 11/16″ long
Port velocity at 150 W31 ft/s
F3 (−3 dB, no cabin gain)30 Hz
Example box (outside)31 1/2″ × 15 3/4″ × 9 1/8″
Open ported box in designer
203040506080100150200606672788490HzdB
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Fs39 Hz
Qts0.87
Qes1.05
Qms5
Vas0.56 ft³
Re (one coil)3 Ω
Sd34.1 in²
Xmax0.33″
Vd11.4 in³ calc.
Mms72 g calc.
BL7.1 T·m calc.
EBP37 — suits sealed calc.
Sensitivity, 1 W / 1 m81.5 dB calc.

General

Size8″
Voice coilsdual 4 Ω
RMS power150 W

Mounting dimensions

Ø≈ 8 5/16″cutout Ø7 1/8″mounting depth 2 11/16″magnet Ø≈ 4 5/8″
Cutout diameter7 1/8″
Mounting depth2 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 Rockford Fosgate 8″ models