Audiobahn AW1251X
12″ subwoofer · 400 W RMS
The Audiobahn AW1251X is a 12″ subwoofer. With Qts 0.46 and EBP 59 it works both sealed and ported: sealed is tighter and smaller, ported is deeper and louder. Modest excursion (Xmax 0.28″) — for clean sound at moderate levels, not for SPL competitions.
| Source | web.archive.org · manufacturer data |
|---|---|
| Checked against source | October 2026 |
| Thiele/Small parameters | not in the spec sheet: Sd — typical value for the size used |
| Mounting dimensions | 3 of 4 — missing: magnet diameter; the designer will use an estimate |
Recommended box
For a sedan, one sub, 400 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 | 52 Hz |
| F3 (−3 dB, no cabin gain) | 50 Hz |
| Example box (outside) | 31 1/2″ × 15 3/4″ × 7 13/16″ |
Ported
deeper, louder| Tuning (Fb) | 33 Hz |
|---|---|
| Port | slot 1 9/16 × 14 5/16″, 20 9/16″ long |
| Port velocity at 400 W | 60 ft/s |
| F3 (−3 dB, no cabin gain) | 33 Hz |
| Example box (outside) | 31 1/2″ × 15 3/4″ × 12 3/8″ |
Deeper: 2.93 ft³ (83 L) tuned to 34 Hz, 31 1/2″ × 15 3/4″ × 15 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 | — |
| RMS power | 400 W |
| Fs | 30 Hz |
| Qts | 0.46 |
| Qes | 0.51 |
| Qms | 4.66 |
| Vas | 3.04 ft³ |
|---|---|
| Re | 3.15 Ω |
| Sd | ≈ 76 in² |
| Xmax | 0.28″ |
| EBP | 59 — sealed or ported calc. |
| Sensitivity, 1 W / 1 m | 88.6 dB calc. |
Mounting dimensions
| Cutout diameter | 10 7/8″ |
|---|---|
| Mounting depth | 5 1/4″ |
| 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 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 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
Other Audiobahn 12″ models
- Audiobahn ALUM12 12″
- Audiobahn ALUM12N 12″ · dual 6 Ω
- Audiobahn ALUM12Q 12″ · dual 6 Ω
- Audiobahn ALUM12X 12″
- Audiobahn AW120Q 12″
- Audiobahn AW120SVC 12″
- Audiobahn AW120T 12″ · 4 Ω
- Audiobahn AW120XS 12″
- Audiobahn AW121T 12″ · 4 Ω
- Audiobahn AW122N 12″ · 4 Ω
- Audiobahn AW122T 12″
- Audiobahn AW1200 12″
Similar 12″ subwoofers from other brands
Close in Fs, Qts and Vas — a box of similar volume will suit them.
- Polk Audio DXi124 DVC 1.62 ft³ sealed · 2.40 ft³ ported
- Machete MS-12 D2 1.73 ft³ sealed · 2.26 ft³ ported
- Blaupunkt BPW-E12S (SVC 4 ohm) 1.73 ft³ sealed · 2.26 ft³ ported
- Quantum Audio QSW12F 1.62 ft³ sealed · 2.40 ft³ ported
- SPL Dynamics V-300S4 1.31 ft³ sealed · 2.01 ft³ ported
- Polk Audio MM124 (Polk/MOMO) 1.41 ft³ sealed · 2.30 ft³ ported
FAQ
What box does the Audiobahn AW1251X need?
Recommended net volume: 1.48 ft³ sealed, 2.26 ft³ ported tuned to 33 Hz — for one sub in a sedan at 400 W. Fit the box to your space and amp in the free calculator, with plans and a cut sheet.
What are the Audiobahn AW1251X Thiele/Small specs?
Fs 30 Hz, Qts 0.46, Vas 3.04 ft³, Xmax 0.28″.
What is the Audiobahn AW1251X mounting depth?
Mounting depth is 5 1/4″, cutout diameter 10 7/8″. The inside depth of the box must exceed the mounting depth by at least 1″.
How much power does the Audiobahn AW1251X handle and how do I wire it?
RMS power rating: 400 W. Wiring for several subs and amp power — in the wiring calculator.
Is the Audiobahn AW1251X better sealed or ported?
EBP 59: both work — sealed 1.48 ft³ is tighter and smaller, ported 2.26 ft³ tuned to 33 Hz is deeper and louder.
What port does the Audiobahn AW1251X need?
For the 2.26 ft³ ported box tuned to 33 Hz: slot 1 9/16 × 14 5/16″, 20 9/16″ long, area 22.6 in²; or a round port Ø5 3/8″, ≈ 20 9/16″ long. Port air speed at 400 W: 60 ft/s.
What box do two Audiobahn AW1251X subs need?
Two subs need twice the volume: 2.97 ft³ sealed, or 4.52 ft³ ported at the same 33 Hz tuning with twice the port area. One shared chamber or one per sub — whatever fits your vehicle.