Polk Audio MM840DVC
8″ subwoofer · dual 4 Ω · 180 W RMS
| 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, 180 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 | 62 Hz |
| F3 (−3 dB, no cabin gain) | 58 Hz |
| Example box (outside) | 10 1/4″ × 10 1/4″ × 14″ |
Ported
deeper, louder| Tuning (Fb) | 44 Hz |
|---|---|
| Port | round port Ø2 1/2″, 10 5/16″ long |
| Port velocity at 180 W | 107 ft/s |
| F3 (−3 dB, no cabin gain) | 42 Hz |
| Example box (outside) | 15 7/8″ × 15 3/4″ × 6 11/16″ |
At 180 W this example’s port will be noisy: air speed 107 ft/s, while the limit is 82 ft/s. It stays quiet up to about 100 W. Full power needs a port of at least 6.5 in², which means a bigger box than this example — size it in the designer.
Open ported box in designerDeeper: 1.38 ft³ (39 L) tuned to 35 Hz, 31 1/2″ × 15 3/4″ × 9 3/8″ 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 | dual 4 Ω |
| RMS power | 180 W |
| Fs | 43 Hz |
| Qts | 0.56 |
| Qes | 0.62 |
| Qms | 5.5 |
| Vas | 0.56 ft³ |
| Re (one coil) | 3.13 Ω |
|---|---|
| Sd | 35.7 in² |
| Xmax | 0.75″ |
| Vd | 26.7 in³ calc. |
| Mms | 65 g calc. |
| BL | 9.4 T·m calc. |
| EBP | 69 — sealed or ported calc. |
| Sensitivity, 1 W / 1 m | 85.1 dB calc. |
Mounting dimensions
| Cutout diameter | 7 1/8″ |
|---|---|
| Mounting depth | 4 1/8″ |
“≈” 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
- web.archive.org/web/20121103011346/http://www.polkaudio.com/downloads/manual/MMs
- web.archive.org/web/20101206235924/http://www.polkaudio.com/downloads/catalogs/2
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 dX8-4 8″ · 4 Ω
- Polk Audio dX8-8 8″ · 8 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 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.
- Kicker Comp 8" 4-Ohm SVC (43C84) 0.57 ft³ sealed · 0.53 ft³ ported
- Morel Ultimo Titanium 804 (SVC 4 ohm) 0.46 ft³ sealed · 0.64 ft³ ported
- Rockville W8K5S4 0.39 ft³ sealed · 0.92 ft³ ported
- Ground Zero GZIW 200X-II (4 Ohm) 0.42 ft³ sealed · 0.49 ft³ ported
- Gladen RS-X 08 Slim D2 (DVC 2 ohm) 0.49 ft³ sealed · 0.53 ft³ ported
- Rockford Fosgate Punch P18S4 (Stage-1, 2004) 0.35 ft³ sealed · 0.49 ft³ ported
FAQ
What box does the Polk Audio MM840DVC need?
Recommended net volume: 0.53 ft³ sealed, 0.57 ft³ ported tuned to 44 Hz — for one sub in a sedan at 180 W. Fit the box to your space and amp in the free calculator, with plans and a cut sheet.
What are the Polk Audio MM840DVC Thiele/Small specs?
Fs 43 Hz, Qts 0.56, Vas 0.56 ft³, Xmax 0.75″, Sd 35.7 in².
What is the Polk Audio MM840DVC mounting depth?
Mounting depth is 4 1/8″, cutout diameter 7 1/8″. The inside depth of the box must exceed the mounting depth by at least 1″.
How much power does the Polk Audio MM840DVC handle and how do I wire it?
RMS power rating: 180 W. Dual 4 Ω voice coils: series gives 8 Ω, parallel gives 2 Ω at the amp. Wiring for several subs and amp power — in the wiring calculator.