I was on my way home tonight and was startled when my subwoofer started rattling loudly. I could here the rattle over the bass and all the other rattling it causes. so I parked it and popped the hatch to listen and it sounds like its coming below the speaker inside of the ported enclosure. I have a kicker L7 and the amp I have does not push as much wattage as the sub(only about 850rms) can take so I find it hard to believe I messed the sub up. I don't know what would be causing that noise. its so loud I had to turn the system off because I couldn't here anything but the rattling from inside the enclosure. the sub was to hot to touch but I'm assuming that's noromal.

any idea? I want to try and fix it before sat!

thanks!

 

sorry man, not a clue. sub to me is the person that takes over teaching kindergarten when my wife is out sick.

 

It is not normal for a sub to be too hot to touch. If it was that hot the sub is probably blown. The rattling sound it's making indicates that also.

Just because the amp's rating is less than the total power handling capability of a sub does not mean the amp can not blow a sub. If you have an amp that is rated lower than the sub and you run the amp into clipping, the power output of the amp can be enough to blow the amp. The clipped signal of the amp has more power than a clean sine wave. This extra power results in excessive heat which ultimately will blow your sub. Think of it as area under the curve in math. You will have more area (power) under a square wave -|_|-| than you will under a sine wave /\/\.

Best advice is to replace the sub with a new one and adjust the gains of the amp to keep it from running into clipping. Heat kills subs.

Mish

 

when you say blown, is that the voice coil that blows? cuz I can jus buy a new voice coil for it..

 

When a speaker "blows" it means the voice coil has failed. The voice coil can unwind from the former, burn, open, or short. Either way the problem can not be fixed by you. The sub will need to be relaced or sent back to Kicker to be reconed. Sorry.

Mish

 

A ported enclosure will unload or lose control below the tuning frequency of the enclosure.
This can be a cause of speaker failure if your not familier with the sounds a speaker can make or if your putting too much power to the speaker.
Im not sure about the L7 drivers but the power rating your talking about might be for a sealed enclosure.
The only way to really be safe with a ported enclosure is to use a subsonic filter set to the tuning frequency that way you can put asmuch power as the driver can handle and not have it unload.

 

excellent info in here...

Having your gains set to amplify a lower voltage signal than you're sending through your RCA's (gains turned up too high) will cause clipping and ultimate demise of the sub in one way or another....

 

is there a way for me to test it once I get it repalced to see if my new gain settings will clip?

 

only way to actually test it is with an Oscilloscope. A good stereo shop should have one... other than that, just turn the gains all the way down, and turn the volume of the HU up as far as possible untill you hear distortion through the regular speakers (you'll know when it distorts), then back it off a notch or 2. This will be your MAX HU volume. With the HU at the MAX you figured, start turning up your gain untill you hear distortion in the sub, then back it off a little. That's all there is to successfully setting your gains.. just remember to not turn it up past the "max" point of the HU volume because that's where clipping will start.

 

ok that makes since no because I would turn the HU up till I heard distortion in my stock speakers and jus turned it down a couple clicks and left it because I didn't here any distortion in my sub. lesson learned. next one I get i'll try and tune myself. need to start learning how to do this stuff so i'm not always taking it to the shop. jus gota wait till I get some $$ to replace it.

would a more powerfull amp help prevent it from clipping?

 

nope.... more power only = more volume.... it's the gain setting that causes clipping....

 

Right procedure, wrong speakers. That is for the main speakers if they are amped. If you do a sub in such a simplistic manner it can easily drown out the mains, particularly in a stock system. The sub gain should be set by ear to blend with the rest of the speakers or by RTA.

 

The gain is the input sensitivity to the amp. Clipping is overdriving the output transistors. There is a relation but only in that if you set the sensitivity too low for the intput signal you will go into overdrive very early. If your amp is clipping you either need a more powerful amp for the output level you desire or you have power problems to the amp.

 

Quickest way to get an idea if the coil is blown is to press down on the cone of the speaker. Do it with both hands spread across the cone to keep the pressure even. If you can feel or hear scratching, you need repairs or replacement. If it moves smoothly, remove the sub from the enclosure. Start by inspecting the enclosure for something that might have shaken loose. If everything is solid, go back to the sub and try the same test as before except pushing outward from the rear of the speaker.
If you still haven't found anything, either post here again with what you've observed for more assistance or go ahead and seek professional help.

 

ok I will go give it a shot right now and report back. thanks! please be the enclosure

 

I took the sub out and checked the enclosure and it seemed fine. so I powered the sub up a little and I could here the rattle coming from one of the two voice coils. the sub is shot. so i'll just need to get another one but I ant an amp that has an equal amount of power this time so I can get the volume I want without the clipping. any amp suggestions around 1500watts rms?

 

Sounds like the coil has likely seperate from the cone. It's pretty much done for.

 

Hey so could a sub be 'partially blown'? I felt the output on my sub was not the same as it used to be but it still can play quite loud. I pressed down on it and it did feel somewhat scratchy. Even though the sub still can play well, has it gone/ is it going bad?

 

If the sub is DVC I think it may still play with one voice coil fried and one working...

if that is the case, you could replace or recone it....

-Tyler