Polk MM840

Polk MM840

$249 $224

8-inch single voice coil subwoofer

SKU: Polk MM840 Categories: ,

New polymer woofer cones and butyl rubber surrounds will not break down over time and will survive the rigors of harsh automotive environments.

High temperature copper voice coil (51mm) and polyamide former withstands the most rigorous use while maintaining extremely low distortion for bass punch and output.

Heavy duty input terminals accommodate speaker wire up to 8 AWG or twisted pairs of 12 AWG.

Advanced carbon composite basket based on the spokes of a wheel is lightweight, will not flex during peaks and looks great! Don’t be afraid to show off the back of your woofer.

Klippel optimized components using a state-of-the-art Klippel distortion analyzer, Polk engineers were able to optimize the woofer’s motor structure, voice coil alignment and suspension for the best possible performance, even at extreme listening levels.

Available matching grille complement the wheel spoke design.

Dual voice coil configuration (MM840DVC) also available.

All Polk products are made using the best materials and the most advanced manufacturing techniques. They pass the industry’s most exhaustive quality tests, including drop testing, extreme signal response and UV & salt exposure testing. Polk loudspeakers are built to perform for a lifetime.

Driver Complement

Quantity 1
Diameter 8″ (20.32cm)
Type Dynamic Balance poly composite woofer


Minimum Impedance 3.3
Total Frequency Response 26-200Hz
Nominal Impedance 4 ohms
Efficiency 90 dB
Power Handling
Continuous 250 watts
Peak 500 watts
Voice Coil
Driver Diameter 1 1/2″ (3.81cm)


Thiele / Small Parameters

Resonant Frequency 35 Hz
Xmax Linear .75
LE 2.3 mH
SD 35.65 sq in/230 sq cm
VAS .54 cu ft/15.4L
QTS .6
QES .7
QMS 5.5


Diameter 7 1/8″ (18.10cm)
Driver Mounting Depth
Top Mount 4 1/8″ (10.48cm)
Bottom Mount 4 11/16″ (11.91cm)


Additional Information

Weight 5 kg
Dimensions 30 x 30 x 30 cm