Personally, I am wondering more and more about the MM12 series subs. As an owner of the OLD DB12 series (MM12's pre- predecessor), I can't help but to wonder why the design of the new subs seems so faulty.
So many subs on the market will take quite a lot of abuse. I find it rather odd how the mm12 will not. Many report from underpowered to overpowered, there is a consistent chain of smoked coils in these subs. Most other subs I hear of burning a coil are either well-used, deliberately overpowered, or at least rare.
Polk's famous mm65xx line has proven the ability of Polk to produce a worthy and superior mobile-audio market driver. The 65's will take all kinds of abuse and keep on going. The older mm subs, and the DB subs, both old and new, are well built drivers and will, again, take quite some abuse before any eminent death. I, myself have run 350 watts of Square-wave (the worst possible signal) to my old DB12's and they will eat it up with a grin... they're rated for 400 wattsrms, and 350 square (100% duty cycle) is 350w rms... Now I just dont get it when people come up with mm12's that fried running anywhere within 50 watts of their 500 rms rating... not to mention those over.
From what I've seen posted about the MM12's it seems like the most common problem has been coil failure. True to Polk, the mechanical suspension seems to hold up very well. Not many other complaints have been made, some about the AL cone paint chipping a little, some about tinsel-tap, and a few about the grilles not quite handling the x-max.
One can't help but wonder if there is a design issue or a material issue with this. Perhaps a series of these subs were made from faulty coil wire... in which case a serial set would be easy enough to check against. Maybe there was a design issue, and they were designed for much less wattage than prescribed on the final product. Perhaps a peice of machinery is winding the coils a little awry?
What could it be? Maybe our freinds here at Polk can give us some insight? We know they have the capability and intelligence to bring us the top-notch products we desire, and would never label a product incorrectly... Unless the first missprint of the box saying it's a 300wrms sub was the correct figure... Honestly, we Polk users just want to know the honest truth.