Soundstream SPLX-122 ('07-'08)
12″ subwoofer · dual 2 Ω · 750 W RMS
The Soundstream SPLX-122 ('07-'08) is a 12″ subwoofer. With Qts 0.49 and EBP 74 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 | 2 of 4 — missing: frame outer diameter, 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) | Flat and accurate · 0.74 |
|---|---|
| Fc | 59 Hz |
| F3 (−3 dB, no cabin gain) | 59 Hz |
| Example box (outside) | 14 3/16″ × 14 3/16″ × 9 11/16″ |
Ported
deeper, louder| Tuning (Fb) | 34 Hz |
|---|---|
| Port | slot 1 9/16 × 14 5/16″, 39 9/16″ long |
| Port velocity at 750 W | 70 ft/s |
| F3 (−3 dB, no cabin gain) | 33 Hz |
| Example box (outside) | 20 3/16″ × 15 3/4″ × 14 3/8″ |
Deeper: 1.66 ft³ (47 L) tuned to 34 Hz, 31 1/2″ × 15 3/4″ × 12″ 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 2 Ω |
| RMS power | 750 W |
| Fs | 39.3 Hz |
| Qts | 0.49 |
| Qes | 0.532 |
| Qms | 6.91 |
| Vas | 0.84 ft³ |
| Re (one coil) | 1.85 Ω |
|---|---|
| Sd | 74.4 in² |
| Xmax | 0.47″ |
| Vd | 35.1 in³ calc. |
| Mms | 225 g calc. |
| BL | 13.9 T·m calc. |
| EBP | 74 — sealed or ported calc. |
| Sensitivity, 1 W / 1 m | 86.3 dB calc. |
Mounting dimensions
| Cutout diameter | 11″ |
|---|---|
| Mounting depth | 7 1/8″ |
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
Other Soundstream 12″ models
- Soundstream EXACT 12 12″ · 4 Ω
- Soundstream PCW-12 12″ · dual 4 Ω
- Soundstream PSW.124 12″ · 4 Ω
- Soundstream PWS-12 12″ · dual 4 Ω
- Soundstream PXW-12 12″ · dual 4 Ω
- Soundstream PXW-12/2 12″ · dual 2 Ω
- Soundstream R1-12 12″ · dual 4 Ω
- Soundstream R1-12L 12″ · dual 4 Ω
- Soundstream R3.12 12″ · dual 2 Ω
- Soundstream RBW-12 12″ · dual 4 Ω
- Soundstream RFW-12 12″ · dual 4 Ω
- Soundstream RW-12 12″ · dual 4 Ω
Similar 12″ subwoofers from other brands
Close in Fs, Qts and Vas — a box of similar volume will suit them.
- Audiobahn AW1205 0.71 ft³ sealed · 1.20 ft³ ported
- AMPIRE BOLD122 0.67 ft³ sealed · 1.13 ft³ ported
- Massive Audio KILOX122 0.71 ft³ sealed · 1.27 ft³ ported
- American Bass XFL-1244 0.83 ft³ sealed · 2.26 ft³ ported
- Machete MF-12R D2 0.71 ft³ sealed · 1.20 ft³ ported
- Quantum Audio QW5000/12D4 0.74 ft³ sealed · 1.31 ft³ ported
FAQ
What box does the Soundstream SPLX-122 ('07-'08) need?
Recommended net volume: 0.67 ft³ sealed, 1.20 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 Soundstream SPLX-122 ('07-'08) Thiele/Small specs?
Fs 39.3 Hz, Qts 0.49, Vas 0.84 ft³, Xmax 0.47″, Sd 74.4 in².
What is the Soundstream SPLX-122 ('07-'08) mounting depth?
Mounting depth is 7 1/8″, cutout diameter 11″. The inside depth of the box must exceed the mounting depth by at least 1″.
How much power does the Soundstream SPLX-122 ('07-'08) handle and how do I wire it?
RMS power rating: 750 W. Dual 2 Ω voice coils: series gives 4 Ω, parallel gives 1 Ω at the amp. Wiring for several subs and amp power — in the wiring calculator.
Is the Soundstream SPLX-122 ('07-'08) better sealed or ported?
EBP 74: both work — sealed 0.67 ft³ is tighter and smaller, ported 1.20 ft³ tuned to 34 Hz is deeper and louder.
What port does the Soundstream SPLX-122 ('07-'08) need?
For the 1.20 ft³ ported box tuned to 34 Hz: slot 1 9/16 × 14 5/16″, 39 9/16″ long, area 22.6 in²; or a round port Ø5 3/8″, ≈ 39 9/16″ long. Port air speed at 750 W: 70 ft/s.
What box do two Soundstream SPLX-122 ('07-'08) subs need?
Two subs need twice the volume: 1.34 ft³ sealed, or 2.40 ft³ ported at the same 34 Hz tuning with twice the port area. One shared chamber or one per sub — whatever fits your vehicle.