For a sedan, one sub, 300 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 Ported · SPL in dB at 1 W / 1 m, no cabin gain
Thiele/Small parameters
Fs
47 Hz
Qts
0.69
Qes
0.75
Qms
8.7
Vas
0.37 ft³
Re
2 Ω
Sd
33.2 in²
Xmax
0.24″
Vd
7.8 in³ calc.
Mms
71 g calc.
BL
7.5 T·m calc.
EBP
63 — sealed or ported calc.
Sensitivity, 1 W / 1 m
83.6 dB calc.
General
Size
8″
Voice coils
2 Ω
RMS power
300 W
Mounting dimensions
Cutout diameter
≈ 7 9/16″
Mounting depth
3″
Overall diameter
8 3/8″
Magnet diameter
5 1/4″
“≈” 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.