For a sedan, one sub, 1,000 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
35.1 Hz
Qts
1.22
Qes
1.412
Qms
9.04
Vas
3.44 ft³
Re (one coil)
≈ 3.4 Ω
Sd
182.6 in²
Xmax
0.91″
Vd
165.3 in³ calc.
Mms
415 g calc.
BL
14.8 T·m calc.
EBP
25 — suits sealed calc.
Sensitivity, 1 W / 1 m
86.7 dB calc.
General
Size
18″
Voice coils
dual 4 Ω
RMS power
1,000 W
Mounting dimensions
Cutout diameter
16 3/4″
Mounting depth
9″
Overall diameter
18 1/2″
“≈” 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.