Polk Audio MM2084

8″ subwoofer · 4 Ω

43 HzFs, resonance

0.65Qts

0.56 ft³Vas

0.33″Xmax

The Polk Audio MM2084 is a 8″ subwoofer. With Qts 0.65 and EBP 63 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, 300 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

0.78 ft³ (22 L)

Net volume

Bass character (Qtc)	Tight and punchy · 0.85
Fc	56 Hz
F3 (−3 dB, no cabin gain)	50 Hz
Example box (outside)	10 1/4″ × 10 1/4″ × 19 7/16″

Open sealed box in designer

Ported

deeper, louder

0.57 ft³ (16 L)

Net volume

Tuning (Fb)	41 Hz
Port	round port Ø2 1/2″, 12 3/16″ long
Port velocity at 300 W	128 ft/s
F3 (−3 dB, no cabin gain)	41 Hz
Example box (outside)	16 1/16″ × 15 3/4″ × 6 11/16″

At 300 W this example’s port will be noisy: air speed 128 ft/s, while the limit is 82 ft/s. It stays quiet up to about 120 W. Full power needs a port of at least 7.8 in², which means a bigger box than this example — size it in the designer.

Open ported box in designer

Deeper: 1.34 ft³ (38 L) tuned to 37 Hz, 31 1/2″ × 15 3/4″ × 9″ outside — a bigger box with flatter deep bass. Open in the calculator

Where to buy Amazon

Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain

Thiele/Small parameters

Size	8″
Voice coils	4 Ω
RMS power	—
Fs	43 Hz
Qts	0.65
Qes	0.68
Qms	15.13
Vas	0.56 ft³

Re	3.3 Ω
Sd	34.7 in²
Xmax	0.33″
Vd	11.3 in³ calc.
Mms	61 g calc.
BL	9 T·m calc.
EBP	63 — sealed or ported calc.
Sensitivity, 1 W / 1 m	84.7 dB calc.

Mounting dimensions

Cutout diameter	7 1/16″
Mounting depth	4 1/4″

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
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

web.archive.org/web/20121103011259/http://www.polkaudio.com/downloads/manual/MOM

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 MM2084	4 Ω	3.3 Ω	0.68	0.56 ft³	0.78 ft³	0.57 ft³ · 41 Hz
Polk Audio MM2084 DVC	dual 4 Ω	3.25 Ω	0.66	0.62 ft³	0.78 ft³	0.57 ft³ · 41 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 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 MM840DVC 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 CompC 8" 4-Ohm SVC (44CWCS84) 0.71 ft³ sealed · 0.92 ft³ ported
Morel Ultimo Titanium 802 (SVC 2 ohm) 0.85 ft³ sealed · 0.64 ft³ ported
Kicker Comp 8" 4-Ohm SVC (43C84) 0.57 ft³ sealed · 0.53 ft³ ported
Kicker CompC 8" 4-Ohm SVC (50CWCS84) 0.71 ft³ sealed · 0.92 ft³ ported
Audison Prima APBMW S8-4.2 (BMW/MINI underseat, SVC 4 ohm) 0.71 ft³ sealed · 0.60 ft³ ported
Rockford Fosgate Punch P3SD2-8 (Shallow) 0.78 ft³ sealed · 0.67 ft³ ported

FAQ

What box does the Polk Audio MM2084 need?

Recommended net volume: 0.78 ft³ sealed, 0.57 ft³ ported tuned to 41 Hz — for one sub in a sedan at 300 W. Fit the box to your space and amp in the free calculator, with plans and a cut sheet.

What are the Polk Audio MM2084 Thiele/Small specs?

Fs 43 Hz, Qts 0.65, Vas 0.56 ft³, Xmax 0.33″, Sd 34.7 in².

What is the Polk Audio MM2084 mounting depth?

Mounting depth is 4 1/4″, cutout diameter 7 1/16″. The inside depth of the box must exceed the mounting depth by at least 1″.

Is the Polk Audio MM2084 better sealed or ported?

EBP 63: both work — sealed 0.78 ft³ is tighter and smaller, ported 0.57 ft³ tuned to 41 Hz is deeper and louder.

What port does the Polk Audio MM2084 need?

For the 0.57 ft³ ported box tuned to 41 Hz: round port Ø2 1/2″, 12 3/16″ long, area 5 in². Port air speed at 300 W: 128 ft/s.

What box do two Polk Audio MM2084 subs need?

Two subs need twice the volume: 1.55 ft³ sealed, or 1.13 ft³ ported at the same 41 Hz tuning with twice the port area. One shared chamber or one per sub — whatever fits your vehicle.