Sky High Car Audio FXB-15 D4
15″ subwoofer · dual 4 Ω · 1,500 W RMS
| 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, 1,500 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| Bass character (Qtc) | Boomy, with a bump · 0.99 |
|---|---|
| Fc | 39 Hz |
| F3 (−3 dB, no cabin gain) | 32 Hz |
| Example box (outside) | 31 1/2″ × 17 11/16″ × 12 1/8″ |
Ported
deeper, louder| Tuning (Fb) | 32 Hz |
|---|---|
| Port | slot 2 3/16 × 16 5/16″, 40 7/8″ long |
| Port velocity at 1,500 W | 60 ft/s |
| F3 (−3 dB, no cabin gain) | 30 Hz |
| Example box (outside) | 24 3/4″ × 17 11/16″ × 16 1/8″ |
Deeper: 4.87 ft³ (138 L) tuned to 28 Hz, 31 1/2″ × 17 11/16″ × 24 15/16″ outside — a bigger box with flatter deep bass. Open in the calculator
Projects with this subwoofer
Boxes that users designed and published: plans, cut sheet and response graph.
Thiele/Small parameters
| Size | 15″ |
|---|---|
| Voice coils | dual 4 Ω |
| RMS power | 1,500 W |
| Fs | 29.3 Hz |
| Qts | 0.74 |
| Qes | 0.83 |
| Qms | 6.68 |
| Vas | 2.31 ft³ |
| Re (one coil) | 3.2 Ω |
|---|---|
| Sd | 126.3 in² |
| Xmax | 1.18″ |
| Vd | 149.1 in³ calc. |
| Mms | 424 g calc. |
| BL | 17.3 T·m calc. |
| EBP | 35 — suits sealed calc. |
| Sensitivity, 1 W / 1 m | 85 dB calc. |
Mounting dimensions
| Cutout diameter | 13 3/4″ |
|---|---|
| Mounting depth | 9″ |
| Overall diameter | 15 1/2″ |
Cone area (Sd) calculated from Fs, Vas and Mms: 126.3 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 Sky High Car Audio 15″ models
- Sky High Car Audio BMX-15 D1 15″ · dual 1 Ω
- Sky High Car Audio BMX-15 D2 15″ · dual 2 Ω
- Sky High Car Audio FE-15 D2 15″ · dual 2 Ω
- Sky High Car Audio FE-15 D4 15″ · dual 4 Ω
- Sky High Car Audio FEX-15 D2 15″ · dual 2 Ω
- Sky High Car Audio FEX-15 D4 15″ · dual 4 Ω
- Sky High Car Audio FMX-15 D1 15″ · dual 1 Ω
- Sky High Car Audio FMX-15 D2 15″ · dual 2 Ω
- Sky High Car Audio FXB-15 D2 15″ · dual 2 Ω
- Sky High Car Audio FXXL-15 D1 15″ · dual 1 Ω
- Sky High Car Audio FXXL-15 D2 15″ · dual 2 Ω
Similar 15″ subwoofers from other brands
Close in Fs, Qts and Vas — a box of similar volume will suit them.
- RE Audio SEX15 D4 v2 2.90 ft³ sealed · 2.01 ft³ ported
- B2 Audio RIOT15 D2 v2 2.97 ft³ sealed · 2.08 ft³ ported
- Memphis Car Audio MJP1522 (MOJO Pro 15" DVC 2ohm) 2.93 ft³ sealed · 2.05 ft³ ported
- Kicker L7 15" 2-Ohm DVC (41L7152) 3.64 ft³ sealed · 4.52 ft³ ported
- B2 Audio IS15 D4 v3 2.83 ft³ sealed · 1.98 ft³ ported
- Cerwin-Vega Mobile VMAX154 (VMAX 15" DVC 4ohm) 2.83 ft³ sealed · 1.80 ft³ ported
FAQ
What box does the Sky High Car Audio FXB-15 D4 need?
Recommended net volume: 2.86 ft³ sealed, 2.01 ft³ ported tuned to 32 Hz — for one sub in a sedan at 1,500 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 FXB-15 D4 Thiele/Small specs?
Fs 29.3 Hz, Qts 0.74, Vas 2.31 ft³, Xmax 1.18″, Sd 126.3 in².
What is the Sky High Car Audio FXB-15 D4 mounting depth?
Mounting depth is 9″, cutout diameter 13 3/4″. The inside depth of the box must exceed the mounting depth by at least 1″.
How much power does the Sky High Car Audio FXB-15 D4 handle and how do I wire it?
RMS power rating: 1,500 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.