Rockford Fosgate Punch SP-812 (1990)

12″ subwoofer · 8 Ω · 100 W RMS

Fs 34 HzQts 0.65Vas 5.16 ft³Xmax 0.24″

Recommended box

For a sedan, one sub, 100 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 volume1.94 ft³ (55 L)
Qtc1.25
Fc65 Hz
F3 (−3 dB, no cabin gain)50 Hz
Example box (outside)31 1/2″ × 15 3/4″ × 9 5/8″
Open sealed box in designer

Ported

Net volume3.28 ft³ (93 L)
Tuning (Fb)47 Hz
Portslot 1 9/16 × 14 5/16″, 4 3/8″ long
Port velocity at 100 W37 ft/s
F3 (−3 dB, no cabin gain)43 Hz
Example box (outside)31 1/2″ × 15 3/4″ × 15 5/16″
Open ported box in designer
2030405060801001502007278849096102HzdB
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Fs34 Hz
Qts0.65
Qes0.84
Qms2.9
Vas5.16 ft³
Re6.7 Ω
Sd84.5 in²
Xmax0.24″
Vd20.3 in³ calc.
Mms63 g calc.
BL10.4 T·m calc.
EBP40 — suits sealed calc.
Sensitivity, 1 W / 1 m90.3 dB calc.

General

Size12″
Voice coils8 Ω
RMS power100 W

Mounting dimensions

Ø12 1/8″cutout Ø11″mounting depth 4 15/16″magnet Ø≈ 7 1/8″
Cutout diameter11″
Mounting depth4 15/16″
Overall diameter12 1/8″

“≈” 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 Rockford Fosgate 12″ models