My subwoofer makes a crackling sound?

So i have 2 12" subwoofers in my truck. i have an 800watt xxx sub that sounds just fine. I used to have a 12 dual sub from walmart hooked up to a separate dual amp that was 500watt that would make a crackling noise which was much more noticeable at a lower volume. i made sure i had a good ground to that amp... show more So i have 2 12" subwoofers in my truck. i have an 800watt xxx sub that sounds just fine. I used to have a 12 dual sub from walmart hooked up to a separate dual amp that was 500watt that would make a crackling noise which was much more noticeable at a lower volume. i made sure i had a good ground to that amp and checked all the wires to make sure they were all connected correctly and were all intact. the other day it would only hit the bass when i would push on the cone. So i thought maybe i blew it but checked the wires to it and it seems just fine. I then went out and bought a 1200watt sub and hooked it up to the same dual amp and it makes the same crackling noise. im under the assumption that my amp or my jvc head unit is going bad but im not sure which one. the strange thing is that the xxx sub hasnt sounded any different since the day i hooked it up. i do have my amps hooked up in parallel with the power comming off of a switch that i can turn them both on and off with. the amps are grounded to the same spot which is a clean bare metal bolt into the seat bracket. im at wits end here and i think the old dual sub i have is still okay and i wouldnt mind having all 3 subs hooked up at once. im an automotive technician and this whole car audio comes fairly easy to me but i need help on this one people. the jvc head unit is about 4 years old, the xxx sub is the exact same age, but the dual sub and amp were only about a year old at most. yes i know they were cheap which is why i think the amp is blown. i do know how to tune an amp to what the subwoofer can put out so i know that is not the issue. any help would be greatly appreciated.
Update: the thing is it is doing it for my new sub that i just put in yesterday to, not just the old one. and it never did it before last month. it is a new thing. i had the sub installed for a year before it started happening and just replaced the sub and its still happening. i replaced the battery, the alternator is a... show more the thing is it is doing it for my new sub that i just put in yesterday to, not just the old one. and it never did it before last month. it is a new thing. i had the sub installed for a year before it started happening and just replaced the sub and its still happening. i replaced the battery, the alternator is a 150 so i know it can handle it because it has for almost a year now. the new sub sounds fine and i know its not blown because it was doing it right away thats why i think it is the head unit going bad or it is the smaller amp
Update 2: The amp is a 400 watt and the sub i had was 500 watt peak so i cranked the amp all the way up and i think that actually overloaded it and may have caused the amp to start clipping which is why i blew the old subwoofer. i think the magnet was heated to much and destroyed the sub. would the amp clipping cause an... show more The amp is a 400 watt and the sub i had was 500 watt peak so i cranked the amp all the way up and i think that actually overloaded it and may have caused the amp to start clipping which is why i blew the old subwoofer. i think the magnet was heated to much and destroyed the sub. would the amp clipping cause an crackling noise in the sub?
Update 3: so i have been playing around with it since i posted this and i have determined that i have a bad radio. i have been going to each individual speaker and listening and when listen closely i hear the crackle in all the speakers. i think my head unit is actually doing the clipping and it is just much more noticeable... show more so i have been playing around with it since i posted this and i have determined that i have a bad radio. i have been going to each individual speaker and listening and when listen closely i hear the crackle in all the speakers. i think my head unit is actually doing the clipping and it is just much more noticeable with my small amp because it doesnt have a limiter such as my large one to prevent to much power from going to the sub. If i was over powering my old sub to long it would explain it going bad because it would have overheated the voice coil. so ill be going out and getting a new head unit to see if that does the trick. but if anyone else has better ideas then send them my way
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