For a sedan, one sub, 750 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
28.9 Hz
Qts
0.55
Qes
0.61
Qms
5.95
Vas
3.13 ft³
Re (one coil)
1.9 Ω
Sd
≈ 124 in²
Xmax
0.71″
EBP
47 — suits sealed calc.
Sensitivity, 1 W / 1 m
87.5 dB calc.
General
Size
15″
Voice coils
dual 2 Ω
RMS power
750 W
Mounting dimensions
Cutout diameter
≈ 13 13/16″
Mounting depth
≈ 7 1/16″
Overall diameter
15 3/8″
“≈” 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.