American Bass XMAXXX-1811

18″ subwoofer · dual 1 Ω · 4,000 W RMS

31.8 HzFs, resonance
0.53Qts
1.89 ft³Vas
0.89″Xmax
4,000 WRMS

Recommended box

For a sedan, one sub, 4,000 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

smaller, tighter
2.24 ft³ (63.5 L)
Net volume
Qtc0.72
Fc43 Hz
F3 (−3 dB, no cabin gain)44 Hz
Example box (outside)20 1/16″ × 20 1/16″ × 13 15/16″
Open sealed box in designer

Ported

deeper, louder
4.66 ft³ (132 L)
Net volume
Tuning (Fb)26 Hz
Portslot 4 3/4 × 19 7/16″, 70″ long
Port velocity at 4,000 W73 ft/s
F3 (−3 dB, no cabin gain)23 Hz
Example box (outside)31 1/2″ × 20 7/8″ × 28 5/16″
Open ported box in designer
203040506080100150200606672788490HzdB
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Fs31.8 Hz
Qts0.53
Qes0.59
Qms5.55
Vas1.89 ft³
Re (one coil)≈ 0.85 Ω
Sd175.9 in²
Xmax0.89″
Vd155.8 in³ calc.
Mms855 g calc.
BL15.7 T·m calc.
EBP54 — sealed or ported calc.
Sensitivity, 1 W / 1 m86.6 dB calc.

General

Size18″
Voice coilsdual 1 Ω
RMS power4,000 W

Mounting dimensions

Ø≈ 18″cutout Ø16 13/16″mounting depth 11 1/2″magnet Ø≈ 10 15/16″
Cutout diameter16 13/16″
Mounting depth11 1/2″

Cone area (Sd) calculated from Fs, Vas and Mms: 175.9 in².

“≈” 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 American Bass 18″ models