I purchased a Pradigm SB100 Passive sub online used. Not sure if it worked because have no amp. Then I remembered I have a JVC RX44 receiver in the bsement from 20 years ago. Hooked up an RCA to sub out on Onkyo deck to phono in on JVC. Then ran speaker wire on channel one out of deck to appropriate inputs on bottom of sub. Turn on theatre deck and JVC and yippee, I got a working sub. I proceed to crank music and watch Top Gun for the next few hours. Everything is good. Two days later, turn all on and got no bass. Sub seems to be not working. Test the JVC and seems to be fine. Hook sub up to truck sub amp and works intermittently for a few seconds and then nothing. I looked at the innards fo the box and all wires seem fine. What are the wire coils inline on the positive hook ups. Are these voice coils. I think I may have overheated these things. Not sure. What have I done wrong. Did smell something hot at the end. I am new to this stuff and fairly ignorant. JVC deck says 225 watts. Thanks