Polk Audio dX8-8
8″ subwoofer · 8 Ω · 200 W RMS
The Polk Audio dX8-8 is a 8″ subwoofer. With Qts 0.55 and EBP 57 it works both sealed and ported: sealed is tighter and smaller, ported is deeper and louder. Modest excursion (Xmax 0.30″) — for clean sound at moderate levels, not for SPL competitions.
| Source | web.archive.org · manufacturer data |
|---|---|
| Checked against source | October 2026 |
| Thiele/Small parameters | complete |
| Mounting dimensions | 1 of 4 — missing: mounting depth, frame outer diameter, magnet diameter; the designer will use an estimate |
Recommended box
For a sedan, one sub, 200 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 | 49 Hz |
| F3 (−3 dB, no cabin gain) | 46 Hz |
| Example box (outside) | 10 1/4″ × 10 1/4″ × 11 5/8″ |
Ported
deeper, louder| Tuning (Fb) | 45 Hz |
|---|---|
| Port | round port Ø2 1/2″, 10 9/16″ long |
| Port velocity at 200 W | 124 ft/s |
| F3 (−3 dB, no cabin gain) | 39 Hz |
| Example box (outside) | 15 5/8″ × 15 3/4″ × 6 1/2″ |
At 200 W this example’s port will be noisy: air speed 124 ft/s, while the limit is 82 ft/s. It stays quiet up to about 85 W. Full power needs a port of at least 7.6 in², which means a bigger box than this example — size it in the designer.
Open ported box in designerDeeper: 1.27 ft³ (36 L) tuned to 27 Hz, 31 1/2″ × 15 3/4″ × 8 5/8″ 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 | 8″ |
|---|---|
| Voice coils | 8 Ω |
| RMS power | 200 W |
| Fs | 34 Hz |
| Qts | 0.55 |
| Qes | 0.6 |
| Qms | 6.99 |
| Vas | 0.46 ft³ |
| Re | 8.6 Ω |
|---|---|
| Sd | 33.2 in² |
| Xmax | 0.30″ |
| Vd | 9.8 in³ calc. |
| Mms | 109 g calc. |
| BL | 18.3 T·m calc. |
| EBP | 57 — sealed or ported calc. |
| Sensitivity, 1 W / 1 m | 81.3 dB calc. |
Mounting dimensions
| Cutout diameter | 7 1/4″ |
|---|---|
| Mounting depth | ≈ 3 15/16″ |
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.
- F-150 SuperCrew — under the rear seat sealed and ported box
- F-150 regular cab — behind the seat sealed and ported box
- Ram Crew Cab — under the rear seat sealed and ported box
- Ram regular cab — behind the seat sealed and ported box
- Tacoma Double Cab — under the rear seat sealed and ported box
- Tacoma Access Cab — behind the front seats sealed and ported 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 and ported box
- Silverado / Sierra regular cab — behind the seat sealed and ported box
- Spare tire well sealed and ported box
- Polaris RZR / Ranger — under the seat sealed and ported box
- Can-Am — under the seat sealed and ported box
- Avalanche — 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
- C10 1973–87 regular cab — 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
- Tesla Model 3 — well under the trunk floor 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
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 |
|---|---|---|---|---|---|---|
| Polk Audio dX8-4 | 4 Ω | 3.7 Ω | 0.48 | 0.50 ft³ | 0.32 ft³ | 0.53 ft³ · 33 Hz |
| Polk Audio dX8-8 | 8 Ω | 8.6 Ω | 0.6 | 0.46 ft³ | 0.42 ft³ | 0.53 ft³ · 45 Hz |
Other Polk Audio 8″ models
- Polk Audio db804 8″ · 4 Ω
- Polk Audio db804DVC 8″ · dual 4 Ω
- Polk Audio db840 8″ · 4 Ω
- Polk Audio db840DVC 8″ · dual 4 Ω
- Polk Audio DXi804 DVC 8″ · dual 4 Ω
- Polk Audio DXi804 SVC 8″ · 4 Ω
- Polk Audio EX8 (EX Series II) 8″ · 4 Ω
- Polk Audio MM840 8″ · 4 Ω
- Polk Audio MM840DVC 8″ · dual 4 Ω
- Polk Audio MM2084 8″ · 4 Ω
- Polk Audio MM2084 DVC 8″ · dual 4 Ω
Similar 8″ subwoofers from other brands
Close in Fs, Qts and Vas — a box of similar volume will suit them.
- Sundown Audio SDv4-8 D2 0.32 ft³ sealed · 0.53 ft³ ported
- Sundown Audio SDv4-8 D4 0.53 ft³ sealed · 0.53 ft³ ported
- Focal Expert P 20 F (Flax, SVC 4 ohm) 0.39 ft³ sealed · 0.53 ft³ ported
- Focal Flax Evo P 20 FE (SVC 4 ohm) 0.39 ft³ sealed · 0.53 ft³ ported
- Hifonics ZST8D2 0.35 ft³ sealed · 0.53 ft³ ported
- Alpine SWR-843D (Type-R) 0.39 ft³ sealed · 0.49 ft³ ported
FAQ
What box does the Polk Audio dX8-8 need?
Recommended net volume: 0.42 ft³ sealed, 0.53 ft³ ported tuned to 45 Hz — for one sub in a sedan at 200 W. Fit the box to your space and amp in the free calculator, with plans and a cut sheet.
What are the Polk Audio dX8-8 Thiele/Small specs?
Fs 34 Hz, Qts 0.55, Vas 0.46 ft³, Xmax 0.30″, Sd 33.2 in².
How much power does the Polk Audio dX8-8 handle and how do I wire it?
RMS power rating: 200 W. Wiring for several subs and amp power — in the wiring calculator.
Is the Polk Audio dX8-8 better sealed or ported?
EBP 57: both work — sealed 0.42 ft³ is tighter and smaller, ported 0.53 ft³ tuned to 45 Hz is deeper and louder.
What port does the Polk Audio dX8-8 need?
For the 0.53 ft³ ported box tuned to 45 Hz: round port Ø2 1/2″, 10 9/16″ long, area 5 in². Port air speed at 200 W: 124 ft/s.
What box do two Polk Audio dX8-8 subs need?
Two subs need twice the volume: 0.85 ft³ sealed, or 1.06 ft³ ported at the same 45 Hz tuning with twice the port area. One shared chamber or one per sub — whatever fits your vehicle.