Fi Audio IB318 v2 S2

18″ subwoofer · 2 Ω · 600 W RMS

Fs 24.4 HzQts 0.80Vas 8.67 ft³Xmax 1.34″

Recommended box

For a sedan, one sub, 600 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 volume4.27 ft³ (121 L)
Qtc1.39
Fc42 Hz
F3 (−3 dB, no cabin gain)31 Hz
Example box (outside)31 1/2″ × 20 7/8″ × 14 7/8″
Open sealed box in designer

Ported

Net volume7.27 ft³ (206 L)
Tuning (Fb)34 Hz
Portslot 2 3/8 × 19 7/16″, 9″ long
Port velocity at 600 W65 ft/s
F3 (−3 dB, no cabin gain)29 Hz
Example box (outside)31 1/2″ × 20 7/8″ × 24 9/16″
Open ported box in designer
2030405060801001502007278849096102HzdB
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Fs24.4 Hz
Qts0.80
Qes0.87
Qms9.56
Vas8.67 ft³
Re1.8 Ω
Sd187.6 in²
Xmax1.34″
Vd251.1 in³ calc.
Mms359 g calc.
BL10.7 T·m calc.
EBP28 — suits sealed calc.
Sensitivity, 1 W / 1 m88.1 dB calc.

General

Size18″
Voice coils2 Ω
RMS power600 W

Mounting dimensions

Ø18 1/2″cutout Ø16 3/4″mounting depth 9 1/2″magnet Ø≈ 10 7/8″
Cutout diameter16 3/4″
Mounting depth9 1/2″
Overall diameter18 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.

Data sources

Other Fi Audio 18″ models