Polk Audio dX8-4

8″ subwoofer · 4 Ω · 200 W RMS

30 HzFs, resonance
0.45Qts
0.50 ft³Vas
0.34″Xmax
200 WRMS
Sourceweb.archive.org · manufacturer data
Checked against sourceOctober 2026
Thiele/Small parameterscomplete
Mounting dimensions1 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
0.32 ft³ (9 L)
Net volume
Bass character (Qtc)Flat and accurate · 0.72
Fc48 Hz
F3 (−3 dB, no cabin gain)50 Hz
Example box (outside)10 1/4″ × 10 1/4″ × 9 1/4″
Open sealed box in designer

Ported

deeper, louder
0.53 ft³ (15 L)
Net volume
Tuning (Fb)33 Hz
Portslot 1 15/16 × 14 5/16″, 126 5/16″ long
Port velocity at 200 W19 ft/s
F3 (−3 dB, no cabin gain)31 Hz
Example box (outside)31 1/2″ × 15 3/4″ × 12 15/16″

The volume and tuning are the recommendation, but the port doesn’t fit this example box. Size the box and port in the designer.

Open ported box in designer

Deeper: 0.74 ft³ (21 L) tuned to 33 Hz, 21 5/8″ × 15 3/4″ × 6 1/2″ outside — a bigger box with flatter deep bass. Open in the calculator

Where to buy Amazon
2030405060801001502006066727884HzdB
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Size8″
Voice coils4 Ω
RMS power200 W
Fs30 Hz
Qts0.45
Qes0.48
Qms6.52
Vas0.50 ft³
Re3.7 Ω
Sd33.2 in²
Xmax0.34″
Vd11.4 in³ calc.
Mms128 g calc.
BL13.6 T·m calc.
EBP63 — sealed or ported calc.
Sensitivity, 1 W / 1 m81.1 dB calc.

Mounting dimensions

Ø≈ 8 7/16″cutout Ø7 1/4″mounting depth ≈ 3 15/16″magnet Ø≈ 4 11/16″
Cutout diameter7 1/4″
Mounting depth≈ 3 15/16″

“≈” 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 8″ models

Similar 8″ subwoofers from other brands

Close in Fs, Qts and Vas — a box of similar volume will suit them.

FAQ

What box does the Polk Audio dX8-4 need?

Recommended net volume: 0.32 ft³ sealed, 0.53 ft³ ported tuned to 33 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 dX8-4 Thiele/Small specs?

Fs 30 Hz, Qts 0.45, Vas 0.50 ft³, Xmax 0.34″, Sd 33.2 in².

How much power does the Polk Audio dX8-4 handle and how do I wire it?

RMS power rating: 200 W. Wiring for several subs and amp power — in the wiring calculator.