Polk MM651 Marine Speaker Review

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  • nominal power: 100 watts
  • peak power: 200 watts
  • impedance: 2.7 ohms
  • sensitivity: 94 dB/W/m
  • frequency response range: 40 – 25,000 Hz
  • unit weight: not specified
  • unit dimensions: 6.5 x 2.88 inches (diameter x depth)
  • warranty: 1 year (applies to purchase from Amazon.com)
  • user manual: click here
  • wireless: no
  • battery life: n/a
  • signal range: n/a

If you’re the kind of person that likes to play it loud, than the MM651’s are designed for you.

This Polk marine speaker set is a very high powered yet still affordable system that will deliver those extra dBs right when you want them the most. The baseline specs are pretty impressive for this model. It’s rare to see a triple digit nominal power for anything under $500, but these speakers are one of them – mostly thanks due to the powerful neodymium magnets and a large 30mm voice coil. The MM651’s also features a light woven glass composite cone on the woofer and a silk dome on the tweeter.

It should be noted from the get go that these marine speakers are designed to be used with an amplifier. You cannot drive them right from the head unit. They have a nominal impedance rating of 2.7 ohms, which is too low for any head unit to handle. We recommend using amplifiers that can drive at least 2 ohms. Go for a better quality amplifier with lower Wattage rating rather than a cheap one with thousands of Watts advertised on its box.

Power: 10/10 – A triple digit nominal power rating is very impressive for a marine speaker set, not to mention one that’s well under $500. The large diameter voice coil makes this possible. The impedance of 2.7 ohms also indicates the use of thick wire on the coil which also increases power handling. The particularly good thing about these speakers is that it maintains a great sensitivity rating of 94dB/W/m. This rating is at the lower border of professional audio systems used in commercial concert venues. With just 10 Watts you will achieve over 100dB of output. To give you an idea of this, a jack hammer at 1 meter away has a noise level of about 100dBs.

Aesthetics & Style: 4.5/5 – We really like the futuristic design of the Polk MM651 set. The grille looks like a cog wheel around the tweeter with 6 spokes coming out of it. It reveals most of the cone which has the honeycomb texture. All in all, they look really cool.

Portability & Convenience: 3/5 – Installing and handling the MM651’s shouldn’t pose too many problems. They have fairly standard dimensions with four point mounting. The grille is held in place by the screws that hold the entire speaker, so it will tough to remove the grille if you need to after they are installed in the cabinets. On the other hand, you will be sure that grille will not fall on its own. One thing to be aware of is that the manufacturer doesn’t specify if the speaker magnets are shielded. Be careful when installing the speaker close to any other magnetic equipment like a compass. The requirement for the use of 1 or more amplifiers might pose an extra hassle with the initial set up too.

Durability: 4/5 – The MM651’s are listed for both marine and car audio systems. They are graded as UV and salt water proof. Most of the cone is exposed, so some extra care should be taken not to pierce or damage it.

Warranty: 3/5 – Polk Audio offers 1 year warranty for their marine speaker systems. It’s a bit on the short side compared to other products and brands, but at least you’ll have coverage from a potentially defective unit.

Price: 10/10 – These are the best power/value per dollar deal we’ve found so far with marine speakers

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Bottom Line: 8.7/10

These speakers offer serious power and potential volume despite being not all that expensive. The manual even warns that high volumes can cause permanent hearing damage. The exceptionally high sensitivity rating of these speakers indicates that the magnet is very strong and the cone is very light and stiff. Both of these traits are very good things for sound quality. They also come with an external crossover that allows you to adjust the tweeter level by 3 dBs. All in all, the Polk MM651 is a marine speaker set that we strongly recommend, especially for those who really want to blast their music.