CT Sounds TROPO-18 D4

18″ subwoofer · dual 4 Ω · 650 W RMS

Fs 23.4 HzQts 0.75Vas 6.83 ft³Xmax 0.53″

Recommended box

For a sedan, one sub, 650 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 volume3.99 ft³ (113 L)
Qtc1.24
Fc39 Hz
F3 (−3 dB, no cabin gain)29 Hz
Example box (outside)31 1/2″ × 20 1/2″ × 14 5/16″
Open sealed box in designer

Ported

Net volume6.82 ft³ (193 L)
Tuning (Fb)30 Hz
Portslot 2 3/8 × 19 1/16″, 14 1/16″ long
Port velocity at 650 W61 ft/s
F3 (−3 dB, no cabin gain)26 Hz
Example box (outside)31 1/2″ × 20 1/2″ × 24 3/16″
Open ported box in designer
203040506080100150200667278849096HzdB
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Fs23.4 Hz
Qts0.75
Qes0.887
Qms5.02
Vas6.83 ft³
Re (one coil)3.36 Ω
Sd175.8 in²
Xmax0.53″
Vd93.4 in³ calc.
Mms435 g calc.
BL15.6 T·m calc.
EBP26 — suits sealed calc.
Sensitivity, 1 W / 1 m86.5 dB calc.

General

Size18″
Voice coilsdual 4 Ω
RMS power650 W

Mounting dimensions

Ø18 3/8″cutout Ø16 11/16″mounting depth 8 1/8″magnet Ø≈ 10 7/8″
Cutout diameter16 11/16″
Mounting depth8 1/8″
Overall diameter18 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.

Data sources

Other CT Sounds 18″ models