Sky High Car Audio FEX-10 D4

10″ subwoofer · dual 4 Ω · 1,250 W RMS

34.8 HzFs, resonance

0.58Qts

0.64 ft³Vas

0.75″Xmax

1,250 WRMS

The Sky High Car Audio FEX-10 D4 is a 10″ subwoofer. With Qts 0.58 and EBP 54 it works both sealed and ported: sealed is tighter and smaller, ported is deeper and louder. Long excursion (Xmax 0.75″) — built for loud music and high power.

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

0.71 ft³ (20 L)

Net volume

Bass character (Qtc)	Tight and punchy · 0.80
Fc	48 Hz
F3 (−3 dB, no cabin gain)	45 Hz
Example box (outside)	12 3/16″ × 12 3/16″ × 12 7/8″

Open sealed box in designer

Ported

deeper, louder

0.81 ft³ (23 L)

Net volume

Tuning (Fb)	38 Hz
Port	round port Ø3″, 13 13/16″ long
Port velocity at 1,250 W	238 ft/s
F3 (−3 dB, no cabin gain)	34 Hz
Example box (outside)	15 7/8″ × 15 3/4″ × 9 1/4″

At 1,250 W this example’s port will be noisy: air speed 238 ft/s, while the limit is 82 ft/s. It stays quiet up to about 140 W. Full power needs a port of at least 20.4 in², which means a bigger box than this example — size it in the designer.

Open ported box in designer

Deeper: 1.98 ft³ (56 L) tuned to 27 Hz, 31 1/2″ × 15 3/4″ × 13 11/16″ 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	10″
Voice coils	dual 4 Ω
RMS power	1,250 W
Fs	34.8 Hz
Qts	0.58
Qes	0.648
Qms	5.24
Vas	0.64 ft³

Re (one coil)	3.3 Ω
Sd	51.2 in²
Xmax	0.75″
Vd	38.3 in³ calc.
Mms	177 g calc.
BL	14.1 T·m calc.
EBP	54 — sealed or ported calc.
Sensitivity, 1 W / 1 m	82.7 dB calc.

Mounting dimensions

Cutout diameter	9 1/16″
Mounting depth	6 3/4″
Overall diameter	10 1/4″

Where it fits in a vehicle

Spots from our vehicle guides where the cutout, mounting depth and recommended box fit. The spot sizes are approximate — measure your own vehicle.

F-150 SuperCrew — under the rear seat sealed and ported box
Ram Crew Cab — under the rear seat sealed and ported box
Tacoma Double Cab — under the rear seat sealed and ported box
Bronco 4-door — behind the rear seat sealed and ported box
Wrangler 4-door, hard top — behind the rear seat sealed and ported box
Wrangler 4-door, soft top — behind the rear seat sealed and ported box
Silverado / Sierra Crew Cab — under the rear seat sealed and ported box
Spare tire well sealed box
Polaris RZR / Ranger — under the seat sealed box
Can-Am — under the seat sealed box
FJ Cruiser — behind the rear seat sealed and ported box
El Camino 1978–87 — behind the seat sealed and ported box
Cherokee XJ — cargo area, spare moved out sealed and ported box
Excursion — behind the third row sealed and ported box
Mustang 2015–2023 coupe — trunk sealed and ported box
Challenger / Charger — trunk sealed and ported box
Tesla Model 3 — well under the trunk floor sealed and ported box
Club Car Precedent — under the rear seat sealed and ported box

“≈” 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-10-subwoofer/

Voice coil versions

The same sub with different voice coils: the parameters are nearly the same — pick by your amp and wiring.

Model	Voice coils	Re	Qes	Vas	Sealed	Ported
Sky High Car Audio FEX-10 D2	dual 2 Ω	2.09 Ω	0.6	0.57 ft³	0.49 ft³	0.81 ft³ · 45 Hz
Sky High Car Audio FEX-10 D4	dual 4 Ω	3.3 Ω	0.648	0.64 ft³	0.71 ft³	0.81 ft³ · 38 Hz

Other Sky High Car Audio 10″ models

Sky High Car Audio BMX-10 D1 10″ · dual 1 Ω
Sky High Car Audio BMX-10 D2 10″ · dual 2 Ω
Sky High Car Audio FE-10 D2 10″ · dual 2 Ω
Sky High Car Audio FE-10 D4 10″ · dual 4 Ω
Sky High Car Audio FXB-10 D2 10″ · dual 2 Ω
Sky High Car Audio FXB-10 D4 10″ · dual 4 Ω

Similar 10″ subwoofers from other brands

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

Memphis Car Audio MJP1022 (MOJO Pro 10" DVC 2ohm) 0.60 ft³ sealed · 0.88 ft³ ported
Earthquake TNT-10S 0.99 ft³ sealed · 0.85 ft³ ported
Rockford Fosgate Power T1S1-10S (Slim, sealed) 0.71 ft³ sealed · 0.88 ft³ ported
Cerwin-Vega Mobile ST104D (Stroker 10" DVC 4ohm) 0.55 ft³ sealed · 1.02 ft³ ported
Soundstream PWS-10 0.81 ft³ sealed · 0.85 ft³ ported
Diamond D910D4 0.57 ft³ sealed · 0.81 ft³ ported

FAQ

What box does the Sky High Car Audio FEX-10 D4 need?

Recommended net volume: 0.71 ft³ sealed, 0.81 ft³ ported tuned to 38 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-10 D4 Thiele/Small specs?

Fs 34.8 Hz, Qts 0.58, Vas 0.64 ft³, Xmax 0.75″, Sd 51.2 in².

What is the Sky High Car Audio FEX-10 D4 mounting depth?

Mounting depth is 6 3/4″, cutout diameter 9 1/16″. 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-10 D4 handle and how do I wire it?

RMS power rating: 1,250 W. Dual 4 Ω voice coils: series gives 8 Ω, parallel gives 2 Ω at the amp. Wiring for several subs and amp power — in the wiring calculator.

Is the Sky High Car Audio FEX-10 D4 better sealed or ported?

EBP 54: both work — sealed 0.71 ft³ is tighter and smaller, ported 0.81 ft³ tuned to 38 Hz is deeper and louder.

What port does the Sky High Car Audio FEX-10 D4 need?

For the 0.81 ft³ ported box tuned to 38 Hz: round port Ø3″, 13 13/16″ long, area 7 in². Port air speed at 1,250 W: 238 ft/s.

What box do two Sky High Car Audio FEX-10 D4 subs need?

Two subs need twice the volume: 1.41 ft³ sealed, or 1.62 ft³ ported at the same 38 Hz tuning with twice the port area. One shared chamber or one per sub — whatever fits your vehicle.