Fi Audio X12 D4
12″ subwoofer · dual 4 Ω · 750 W RMS
The Fi Audio X12 D4 is a 12″ subwoofer. With Qts 0.47 and EBP 62 it works both sealed and ported: sealed is tighter and smaller, ported is deeper and louder.
| Source | web.archive.org · 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, 750 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 | 53 Hz |
| F3 (−3 dB, no cabin gain) | 51 Hz |
| Example box (outside) | 14 3/16″ × 14 3/16″ × 11 15/16″ |
Ported
deeper, louder| Tuning (Fb) | 34 Hz |
|---|---|
| Port | slot 1 9/16 × 14 5/16″, 36″ long |
| Port velocity at 750 W | 65 ft/s |
| F3 (−3 dB, no cabin gain) | 34 Hz |
| Example box (outside) | 21 7/16″ × 15 3/4″ × 13 3/4″ |
Deeper: 2.86 ft³ (81 L) tuned to 29 Hz, 31 1/2″ × 15 3/4″ × 17 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 | 12″ |
|---|---|
| Voice coils | dual 4 Ω |
| RMS power | 750 W |
| Fs | 31.6 Hz |
| Qts | 0.47 |
| Qes | 0.51 |
| Qms | 6.51 |
| Vas | 1.63 ft³ |
| Re (one coil) | 2.8 Ω |
|---|---|
| Sd | 74.4 in² |
| Xmax | 0.79″ |
| Vd | 58.6 in³ calc. |
| Mms | 180 g calc. |
| BL | 14 T·m calc. |
| EBP | 62 — sealed or ported calc. |
| Sensitivity, 1 W / 1 m | 86.6 dB calc. |
Mounting dimensions
| Cutout diameter | 11 1/8″ |
|---|---|
| Mounting depth | 6 1/2″ |
| Overall diameter | 12 1/2″ |
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.
- 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
- 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
- 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
- web.archive.org/web/20151204181607/http://www.ficaraudio.com:80/product/x-series
- web.archive.org/web/20181115115452/http://www.ficaraudio.com:80/product/x-series
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 |
|---|---|---|---|---|---|---|
| Fi Audio X12 S2 | 2 Ω | 1.9 Ω | 0.47 | 1.79 ft³ | 0.74 ft³ | 1.45 ft³ · 34 Hz |
| Fi Audio X12 S4 | 4 Ω | 2.9 Ω | 0.47 | 1.79 ft³ | 0.74 ft³ | 1.45 ft³ · 34 Hz |
| Fi Audio X12 D2 | dual 2 Ω | 1.4 Ω | 0.51 | 1.63 ft³ | 0.88 ft³ | 1.31 ft³ · 34 Hz |
| Fi Audio X12 D4 | dual 4 Ω | 2.8 Ω | 0.51 | 1.63 ft³ | 0.88 ft³ | 1.31 ft³ · 34 Hz |
Other Fi Audio 12″ models
- Fi Audio Alpha 12 S2 12″ · 2 Ω
- Fi Audio Alpha 12 S4 12″ · 4 Ω
- Fi Audio Alpha v1 12 S1 12″ · 1 Ω
- Fi Audio Alpha v1 12 S2 12″ · 2 Ω
- Fi Audio Alpha v1 12 S4 12″ · 4 Ω
- Fi Audio Alpha v2 12 S2 12″ · 2 Ω
- Fi Audio Alpha v2 12 S4 12″ · 4 Ω
- Fi Audio Alpha v2.1 12 S2 12″ · 2 Ω
- Fi Audio Alpha v2.1 12 S4 12″ · 4 Ω
- Fi Audio BL-NEO 12 D1 12″ · dual 1 Ω
- Fi Audio BL-NEO 12 D2 12″ · dual 2 Ω
- Fi Audio BL12 D1 12″ · dual 1 Ω
Similar 12″ subwoofers from other brands
Close in Fs, Qts and Vas — a box of similar volume will suit them.
- Soundstream T7.122 0.92 ft³ sealed · 1.31 ft³ ported
- SSA GCON 12 D2 0.85 ft³ sealed · 1.24 ft³ ported
- Bomber Bicho Papão 800W 4+4 Ohm (SW12BP-800-4+4) 0.88 ft³ sealed · 1.27 ft³ ported
- Machete M12 v2 D2 0.74 ft³ sealed · 1.20 ft³ ported
- Ground Zero GZRW 12D4 (2x4 Ohm) 0.95 ft³ sealed · 1.34 ft³ ported
- JBL W12GTi / W12GTi MkII 1.06 ft³ sealed · 1.27 ft³ ported
FAQ
What box does the Fi Audio X12 D4 need?
Recommended net volume: 0.88 ft³ sealed, 1.31 ft³ ported tuned to 34 Hz — for one sub in a sedan at 750 W. Fit the box to your space and amp in the free calculator, with plans and a cut sheet.
What are the Fi Audio X12 D4 Thiele/Small specs?
Fs 31.6 Hz, Qts 0.47, Vas 1.63 ft³, Xmax 0.79″, Sd 74.4 in².
What is the Fi Audio X12 D4 mounting depth?
Mounting depth is 6 1/2″, cutout diameter 11 1/8″. The inside depth of the box must exceed the mounting depth by at least 1″.
How much power does the Fi Audio X12 D4 handle and how do I wire it?
RMS power rating: 750 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 Fi Audio X12 D4 better sealed or ported?
EBP 62: both work — sealed 0.88 ft³ is tighter and smaller, ported 1.31 ft³ tuned to 34 Hz is deeper and louder.
What port does the Fi Audio X12 D4 need?
For the 1.31 ft³ ported box tuned to 34 Hz: slot 1 9/16 × 14 5/16″, 36″ long, area 22.6 in²; or a round port Ø5 3/8″, ≈ 36″ long. Port air speed at 750 W: 65 ft/s.
What box do two Fi Audio X12 D4 subs need?
Two subs need twice the volume: 1.77 ft³ sealed, or 2.61 ft³ ported at the same 34 Hz tuning with twice the port area. One shared chamber or one per sub — whatever fits your vehicle.