Fi Audio Xv5 18 D1
18″ subwoofer · dual 1 Ω · 1,500 W RMS
| Source | ficaraudio.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 |
- Fs, Vas and Sd don't match the moving mass of 441 g (they give 314 g) — one of the spec sheet values is probably wrong.
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) | Tight and punchy · 0.80 |
|---|---|
| Fc | 55 Hz |
| F3 (−3 dB, no cabin gain) | 52 Hz |
| Example box (outside) | 20 1/16″ × 20 1/16″ × 15 7/16″ |
Ported
deeper, louder| Tuning (Fb) | 34 Hz |
|---|---|
| Port | slot 3 1/8 × 19 7/16″, 26 7/16″ long |
| Port velocity at 1,500 W | 62 ft/s |
| F3 (−3 dB, no cabin gain) | 34 Hz |
| Example box (outside) | 31 1/2″ × 20 7/8″ × 18 3/16″ |
Deeper: 6.85 ft³ (194 L) tuned to 32 Hz, 31 1/2″ × 20 7/8″ × 26 1/16″ 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 | 18″ |
|---|---|
| Voice coils | dual 1 Ω |
| RMS power | 1,500 W |
| Fs | 31.2 Hz |
| Qts | 0.45 |
| Qes | 0.5 |
| Qms | 4.78 |
| Vas | 5.37 ft³ |
| Re (one coil) | 1.01 Ω |
|---|---|
| Sd | 176.7 in² |
| Xmax | 1.14″ |
| Vd | 201.8 in³ calc. |
| Mms | 314 g calc. |
| BL | 11.2 T·m calc. |
| EBP | 62 — sealed or ported calc. |
| Sensitivity, 1 W / 1 m | 91.7 dB calc. |
Mounting dimensions
| Cutout diameter | 16 7/8″ |
|---|---|
| Mounting depth | 9 15/16″ |
| Overall diameter | 18 1/2″ |
Judging by its value, the published Re is for both coils in series — converted to per coil.
“≈” 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 Fi Audio 18″ models
- Fi Audio BL-NEO 18 D1 18″ · dual 1 Ω
- Fi Audio BL-NEO 18 D2 18″ · dual 2 Ω
- Fi Audio BL18v3 D1 18″ · dual 1 Ω
- Fi Audio BL18v3 D2 18″ · dual 2 Ω
- Fi Audio BL18v3.1 D1 18″ · dual 1 Ω
- Fi Audio BL18v3.1 D2 18″ · dual 2 Ω
- Fi Audio BTL-NEO18 D1 18″ · dual 1 Ω
- Fi Audio BTL-NEO18 D2 18″ · dual 2 Ω
- Fi Audio BTL3 18 D1 18″ · dual 1 Ω
- Fi Audio BTL3 18 D2 18″ · dual 2 Ω
- Fi Audio BTL4 18 D1 18″ · dual 1 Ω
- Fi Audio BTL4 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 XL-SPL 18 D1 4.03 ft³ sealed · 4.06 ft³ ported
- DC Audio XL-SPL 18 D2 4.03 ft³ sealed · 4.06 ft³ ported
- DC Audio XL-SPL 18 D4 4.03 ft³ sealed · 4.06 ft³ ported
- Sundown Audio Uv1-18 D4 1.80 ft³ sealed · 5.90 ft³ ported
- SPL Dynamics SPL-460D1A 1.92 ft³ sealed · 5.65 ft³ ported
- Deaf Bonce Apocalypse DB-SA418 D1 2.47 ft³ sealed · 4.94 ft³ ported
FAQ
What box does the Fi Audio Xv5 18 D1 need?
Recommended net volume: 2.54 ft³ sealed, 4.31 ft³ ported tuned to 34 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 Fi Audio Xv5 18 D1 Thiele/Small specs?
Fs 31.2 Hz, Qts 0.45, Vas 5.37 ft³, Xmax 1.14″, Sd 176.7 in².
What is the Fi Audio Xv5 18 D1 mounting depth?
Mounting depth is 9 15/16″, cutout diameter 16 7/8″. The inside depth of the box must exceed the mounting depth by at least 1″.
How much power does the Fi Audio Xv5 18 D1 handle and how do I wire it?
RMS power rating: 1,500 W. Dual 1 Ω voice coils: series gives 2 Ω, parallel gives 0.5 Ω at the amp. Wiring for several subs and amp power — in the wiring calculator.