May be time for new cones or speakers. What is this about "range"? Specs would be from the maker as to some things but given your story so far, there is nothing that range would matter.
I have some questions about my speakers that I am using with a subwoofer. I have some Yamaha NS-A635A bookshelf speakers and I am not sure what their range is. I want to know so that I can set the crossover correctly on the subwoofer. Can you help? Also one of the subwoofers on one of the speakers itself has been sounding distorted lately. It sounds loose and it sort of rattles. Any idea what this could be and how I could fix this?