Rockford Fosgate Punch P18S4 (Stage-1, 2004)

8″ subwoofer · 4 Ω · 150 W RMS

Fs 40 HzQts 0.53Vas 0.48 ft³Xmax 0.28″

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 volume0.35 ft³ (10 L)
Qtc0.81
Fc61 Hz
F3 (−3 dB, no cabin gain)57 Hz
Example box (outside)10 1/4″ × 10 1/4″ × 10 1/16″
Open sealed box in designer

Ported

Net volume1.13 ft³ (32 L)
Tuning (Fb)33 Hz
Portround port Ø2 1/2″, 9″ long
Port velocity at 150 W148 ft/s
F3 (−3 dB, no cabin gain)29 Hz
Example box (outside)29 3/4″ × 15 3/4″ × 6 1/2″
Open ported box in designer
203040506080100150200606672788490HzdB
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Fs40 Hz
Qts0.53
Qes0.57
Qms6.89
Vas0.48 ft³
Re3.2 Ω
Sd31 in²
Xmax0.28″
Vd8.5 in³ calc.
Mms66 g calc.
BL9.7 T·m calc.
EBP70 — sealed or ported calc.
Sensitivity, 1 W / 1 m83.8 dB calc.

General

Size8″
Voice coils4 Ω
RMS power150 W

Mounting dimensions

Ø8 3/4″cutout Ø7 1/16″mounting depth 4 1/16″magnet Ø≈ 4 9/16″
Cutout diameter7 1/16″
Mounting depth4 1/16″
Overall diameter8 3/4″

“≈” 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