Looking for feedback on why I got coil rub now.

[tundra2000boy]

Bought Dc audio lvl 5 elite 12in 1 ohm version ( wired parallel) with the added spider and spl neck about 4 years ago. 

 

What I have 

-1.5 cu ft box that they recommended the size of 

- 48ah plannano bank ( amp only 2ft away from )

- 240 amp alt

- didn't set the subsonic yet but I know 25hz and under the voice coil would hit at volume 25 on the head unit. Only did that once.

 

Had deaf bonce aak-4000.1d but then switched up to the taramps smart 5k bass and now trying out the stinger 4000.1.

I have the smd amm-1 and dd1 on hand so I'm 90% sure i set head unit and amp gain right with all the amps.

 

There was a couple times I hit soft clip with the smart 5k just trying to see what numbers I was getting which i could only get around 2,000 watts at 2.6 ohms so that's why I wanted to try the stinger since it's somewhat cheaper and look like it put out more at 2 ohm than the taramps.

Adjusted gain on the stinger by looking at the clip light with head unit at 30 out of 40 ( clean signal up to 39 volume) but noticed playing 40hz -5db track after the first time with about maybe 1 min of total of play time I started to smell the glue of the voice coil ( dust cap was pretty warm ) so I waited a little bit then hooked up the smd amm-1 which that showed i could bump the gain up just a little more.

Decided on trying a test tones sweep to see if it was putting out more than the smart 5k which it was but I think part of the problem was when I hit the sweep track I didn't turn it down so when it played from 20hz to about 26hz I could hear the coil bottoming out. So after the sweep I decided to try the 40hz -5 db track again and after about 10-15 seconds I could smell the coil again so I stopped for the night and switched it over to the radio at low volume and noticed a rattling type sound coming from it. Once it cooled down I pushed on the cone and now it makes that scratching scraping sound. 

I pulled the sub out and everything looks fine but when I tested each coil they were about 2.5 ohms but the one side of the coil i noticed the reading would fluctuate if I moved the direct leads wires around at the basket.

I do have a oscilloscope that I can look at the signal if needed but what do you think i did or what happen that cause the coil to rub now?

 

[EricM9104]

When a speaker is driven to the point of audible bottoming out and smelling, it's expected to do this... That scraping sound you're hearing is the voice coil unraveling itself inside of the motor/magnet assembly, which would also cause the resistance readings to be higher and/or eventually 0L.. Even if it was a clean signal, over-powering the subwoofer incorrectly will cause mechanical damage.

[crispy_chick3n]

^^^^ what he said. heat and bottoming out are 2 big killers for subs. at this point you could either recone it, or just let it eat till it's done, but you've for sure started the clock on that coil going out