Sky High Car Audio FEX-18 D2

18″ subwoofer · dual 2 Ω · 1,250 W RMS

27.7 HzFs, resonance

0.71Qts

7.87 ft³Vas

0.75″Xmax

1,250 WRMS

Source	skyhighcaraudio.com · manufacturer data
Checked against source	October 2026
Thiele/Small parameters	complete
Mounting dimensions	3 of 4 — missing: magnet diameter; the designer will use an estimate

Recommended box

For a sedan, one sub, 1,250 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

4.34 ft³ (123 L)

Net volume

Bass character (Qtc)	Boomy, with a bump · 1.18
Fc	46 Hz
F3 (−3 dB, no cabin gain)	36 Hz
Example box (outside)	31 1/2″ × 20 1/16″ × 15 11/16″

Open sealed box in designer

Ported

deeper, louder

5.62 ft³ (159 L)

Net volume

Tuning (Fb)	30 Hz
Port	slot 2 9/16 × 18 11/16″, 19 9/16″ long
Port velocity at 1,250 W	63 ft/s
F3 (−3 dB, no cabin gain)	30 Hz
Example box (outside)	31 1/2″ × 20 1/16″ × 21 9/16″

Open ported box in designer

Deeper: 7.35 ft³ (208 L) tuned to 35 Hz, 31 1/2″ × 20 1/16″ × 26 13/16″ outside — a bigger box with flatter deep bass. Open in the calculator

Where to buy Amazon

Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Size	18″
Voice coils	dual 2 Ω
RMS power	1,250 W
Fs	27.7 Hz
Qts	0.71
Qes	0.79
Qms	6.7
Vas	7.87 ft³

Re (one coil)	2.15 Ω
Sd	189.9 in²
Xmax	0.75″
Vd	142.1 in³ calc.
Mms	315 g calc.
BL	12.2 T·m calc.
EBP	35 — suits sealed calc.
Sensitivity, 1 W / 1 m	89.8 dB calc.

Mounting dimensions

Cutout diameter	16 1/4″
Mounting depth	9 3/8″
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.

Data sources

skyhighcaraudio.com/sky-high-car-audio-fex-series-18-subwoofer/

Other Sky High Car Audio 18″ models

Sky High Car Audio BMX-18 D1 18″ · dual 1 Ω
Sky High Car Audio BMX-18 D2 18″ · dual 2 Ω
Sky High Car Audio FEX-18 D4 18″ · dual 4 Ω
Sky High Car Audio FMX-18 D1 18″ · dual 1 Ω
Sky High Car Audio FMX-18 D2 18″ · dual 2 Ω
Sky High Car Audio FXB-18 D2 18″ · dual 2 Ω
Sky High Car Audio FXB-18 D4 18″ · dual 4 Ω
Sky High Car Audio FXXL-18 D1 18″ · dual 1 Ω
Sky High Car Audio FXXL-18 D2 18″ · dual 2 Ω

Similar 18″ subwoofers from other brands

Close in Fs, Qts and Vas — a box of similar volume will suit them.

DC Audio Level 4 M3 18 D1 4.31 ft³ sealed · 4.94 ft³ ported
DC Audio Level 4 M3 18 D2 4.31 ft³ sealed · 4.94 ft³ ported
DC Audio Level 4 M3 18 D4 4.31 ft³ sealed · 4.94 ft³ ported
PSI Platform 2 18 4.34 ft³ sealed · 5.65 ft³ ported
URAL Bulava 18 (2+2) 4.20 ft³ sealed · 4.66 ft³ ported
DC Audio Level 3 M3 18 D1 4.31 ft³ sealed · 5.23 ft³ ported

FAQ

What box does the Sky High Car Audio FEX-18 D2 need?

Recommended net volume: 4.34 ft³ sealed, 5.62 ft³ ported tuned to 30 Hz — for one sub in a sedan at 1,250 W. Fit the box to your space and amp in the free calculator, with plans and a cut sheet.

What are the Sky High Car Audio FEX-18 D2 Thiele/Small specs?

Fs 27.7 Hz, Qts 0.71, Vas 7.87 ft³, Xmax 0.75″, Sd 189.9 in².

What is the Sky High Car Audio FEX-18 D2 mounting depth?

Mounting depth is 9 3/8″, cutout diameter 16 1/4″. The inside depth of the box must exceed the mounting depth by at least 1″.

How much power does the Sky High Car Audio FEX-18 D2 handle and how do I wire it?

RMS power rating: 1,250 W. Dual 2 Ω voice coils: series gives 4 Ω, parallel gives 1 Ω at the amp. Wiring for several subs and amp power — in the wiring calculator.