Old School crunch subs

[Knocker]

I bought a pair of crunch drive series 15's (ds-15) in a box for 10$. They have about 1.2 cu foot per sub in a sealed box. They fail at low frequencies because of their extremely limited excursion probably 6-8 mm and they make virtually no sound from 40hz-60hz and they only get loud at above about 100 hz. They say 350 watt I think that is an rms claim but it doesn't specify. I am also assuming that they were produced in different years because they have different magnet structures. Are these subs really that bad I gave them plenty of power (600 watts rms) and the box is sealed fairly well i checked inside and cut some carpeting off to check.

Are they both in the same sealed enclosure without a divider? If they have different magnet structures maybe it's possible they have different Thiel Small Parameters and shouldn't be in the same box together. If they ARE sharing an an enclosure then maybe take one out and block the hole and run the other one alone and see what happens. If there IS a divider then disconnect one and run the other one alone. If they were out of phase then the solo driver should start making some bass. Just some ideas.