Polk Audio EX12 (EX Series II)
12″ subwoofer · 4 Ω · 150 W RMS
The Polk Audio EX12 (EX Series II) is a 12″ subwoofer. With Qts 0.30 and EBP 79 it works both sealed and ported: sealed is tighter and smaller, ported is deeper and louder. Modest excursion (Xmax 0.18″) — 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 | 2 of 4 — missing: frame outer diameter, magnet diameter; the designer will use an estimate |
Recommended box
For a sedan, one sub, 150 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 · 0.81 |
|---|---|
| Fc | 66 Hz |
| F3 (−3 dB, no cabin gain) | 63 Hz |
| Example box (outside) | 14 3/16″ × 14 3/16″ × 10 7/16″ |
Ported
deeper, louder| Tuning (Fb) | 30 Hz |
|---|---|
| Port | slot 1 9/16 × 14 5/16″, 25 3/4″ long |
| Port velocity at 150 W | 37 ft/s |
| F3 (−3 dB, no cabin gain) | 34 Hz |
| Example box (outside) | 31 1/2″ × 15 3/4″ × 12 3/4″ |
Deeper: 2.19 ft³ (62 L) tuned to 33 Hz, 31 1/2″ × 15 3/4″ × 12 1/8″ 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 | 4 Ω |
| RMS power | 150 W |
| Fs | 24.5 Hz |
| Qts | 0.30 |
| Qes | 0.31 |
| Qms | 8.14 |
| Vas | 4.66 ft³ |
|---|---|
| Re | 3.38 Ω |
| Sd | ≈ 76 in² |
| Xmax | 0.18″ |
| EBP | 79 — sealed or ported calc. |
| Sensitivity, 1 W / 1 m | 90 dB calc. |
Mounting dimensions
| Cutout diameter | 10 7/8″ |
|---|---|
| Mounting depth | 5 5/16″ |
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.
- Tacoma Access Cab — behind the front seats sealed 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 box
- Spare tire well 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 Polk Audio 12″ models
- Polk Audio db124 12″ · 4 Ω
- Polk Audio db124DVC 12″ · dual 4 Ω
- Polk Audio db1240 12″ · 4 Ω
- Polk Audio db1240DVC 12″ · dual 4 Ω
- Polk Audio dX12-4 12″ · 4 Ω
- Polk Audio dX12-8 12″ · 8 Ω
- Polk Audio DXi124 DVC 12″ · dual 4 Ω
- Polk Audio DXi124 SVC 12″ · 4 Ω
- Polk Audio DXi1240DVC 12″ · dual 4 Ω
- Polk Audio GXR124 12″ · 4 Ω
- Polk Audio MM120-4 12″ · 4 Ω
- Polk Audio MM124 (Polk/MOMO) 12″ · 4 Ω
Similar 12″ subwoofers from other brands
Close in Fs, Qts and Vas — a box of similar volume will suit them.
- Orion XtrPro 12D (2000) 0.88 ft³ sealed · 2.40 ft³ ported
- SPL Dynamics V-12S4 0.81 ft³ sealed · 2.44 ft³ ported
- Dayton Audio SD315A-88 1.13 ft³ sealed · 2.40 ft³ ported
- Orion 2NT 12 SVC 0.71 ft³ sealed · 2.30 ft³ ported
- Helix W12 Competition (1x4 Ohm) 0.74 ft³ sealed · 2.37 ft³ ported
- SPL Dynamics V-12S 1.02 ft³ sealed · 2.37 ft³ ported
FAQ
What box does the Polk Audio EX12 (EX Series II) need?
Recommended net volume: 0.74 ft³ sealed, 2.26 ft³ ported tuned to 30 Hz — for one sub in a sedan at 150 W. Fit the box to your space and amp in the free calculator, with plans and a cut sheet.
What are the Polk Audio EX12 (EX Series II) Thiele/Small specs?
Fs 24.5 Hz, Qts 0.30, Vas 4.66 ft³, Xmax 0.18″.
What is the Polk Audio EX12 (EX Series II) mounting depth?
Mounting depth is 5 5/16″, 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 Polk Audio EX12 (EX Series II) handle and how do I wire it?
RMS power rating: 150 W. Wiring for several subs and amp power — in the wiring calculator.
Is the Polk Audio EX12 (EX Series II) better sealed or ported?
EBP 79: both work — sealed 0.74 ft³ is tighter and smaller, ported 2.26 ft³ tuned to 30 Hz is deeper and louder.
What port does the Polk Audio EX12 (EX Series II) need?
For the 2.26 ft³ ported box tuned to 30 Hz: slot 1 9/16 × 14 5/16″, 25 3/4″ long, area 22.6 in²; or a round port Ø5 3/8″, ≈ 25 3/4″ long. Port air speed at 150 W: 37 ft/s.
What box do two Polk Audio EX12 (EX Series II) subs need?
Two subs need twice the volume: 1.48 ft³ sealed, or 4.52 ft³ ported at the same 30 Hz tuning with twice the port area. One shared chamber or one per sub — whatever fits your vehicle.