I think I'm in need of a replacement set of front channel speakers..

My Polks seem to have started to become distorted at lower frequencies.
My previous units, Bostons, had the foam fail (adhesive fail, they were a bit 'old')
I took a look at the Polk ones, and they look intact.  They sound great except when there
is a low frequency component. These are quite a few years old as well.

They serve as my LF and RF channels in a  6.1 system.  These were rated well past the
maximum output of the receiver and I don't ever get close to that.

any recommendations for replacements units? or maybe just replace the speakers (?)

Amplifier clipping is what kills speakers.  It's like applying DC current to the coil while clipping.  This leads to excessive internal.  

Have you double-checked your connections and settings?  You wouldn't expect they'd distort with lower frequencies if they were set to "Small" and those were being sent to your sub.

I guess I could check that out.. I haven't changed anything. everything was set up with the Spears and Munsil benchmark dvd and until recently, had not had any problems.

OK, based on that...





What's their model number?  eta: I assumed you were referring to front effects speakers.  Is this correct, or are we talking about your main L/R speakers?





It's a process of
elimination.  I would confirm that they were in fact damaged before
replacing them.  You could hook them up as the mains, or to another
receiver, and play stereo music through them as a quick test.





Once
you confirm they're toast, then the question becomes "are they worth
fixing?'.  Woofer foam-surround replacement isn't a big deal but you
said that looked OK.  





What are your current main and surround speakers?
You should sonically match those as closely as possible, if you determine replacement is necessary.






 

Other than the foam which can be replaced, speakers don't wear out. Maybe the capacitors in the crossover start leaking but that is more rare than the foam issue.  My in-laws have some Altec Lansing speakers from the 70's that rock.  I refoamed the woofers about 20 years ago and they are still going strong.