Weird knocking sound - I'm a totally clueless

[DidUHearThat? 10+ year member]

I cant even imagine how you think its possible the sub is making contact with the back of his box when playing.

Lots of very strange advice in this thread. Looking at the picture it seems like the lame temp install is the problem.

 

[Apollo220 10+ year member]

I cant even imagine how you think its possible the sub is making contact with the back of his box when playing.

well the box looks like a flimsy box not made for a heavy sub . could be box flex if the box is broken ? shoot i don't know anything is possible

 

[DidUHearThat? 10+ year member]

well the box looks like a flimsy box not made for a heavy sub . could be box flex if the box is broken ? shoot i don't know anything is possible

No. The box looks fine. It's not a jiggawatt 18" vented sub.

Just to go further down the rabbit hole... why would a broken box "flex"? If it's broken... the it's not going to flex is it?

 

[Vossy 10+ year member]

Looks like the box if you ask me. Try another one lol. My buddies type X's did the same shit, rescrewed all of the baffles and sides of the box. Works fine.

Try screwing the sides of your box for a more "tight" box.

 

[Apollo220 10+ year member]

No. The box looks fine. It's not a jiggawatt 18" vented sub.
Just to go further down the rabbit hole... why would a broken box "flex"? If it's broken... the it's not going to flex is it?

no not now!! but before it could have when his sub cut off !! and if he is hearing a crackling noise when pushing on the box it more then likely damaged . please read all the posts before you comment //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif//content.invisioncic.com/y282845/emoticons/*******.gif.a649d21efc0d1fd4890a6428166586c1.gif

 

[Nicktkd18]

Well it could be your box or not. try another box or a friends box. Just because hes not hearing the noise free air doesnt mean its not the sub. If the magnet or spider is loose you might not hear it free air bc it might need that pressure it gets from being mounted in the box and or being mounted on the side instead of the top. try positioning the box facing up and different directions see if its not as loud or takes more or less power before hearing the noise.

 

[goingdef 10+ year member]

Going by free-air sound vs. in the box I would say that box has a split in one of the seems and the sub is fine unless you keep rubbing the coil on the motor like in vid#2, it hurt watching that like a video of someone clubbing baby seals!

 

[stanky1219]

the glue on the surround of my l7 8" came apart and when i glued it back together is wasnt aligned properly and it sounded like that. and the fact that he gets massive scraping when he pushes on one side of the sub leads me to think that maybe the sub heated up enough (From playing it hard or just being sealed up in a hot vehicle) to get the glue hot enough for the coil former to actually move to one side a little and depending how large the gap on the pole piece is a little could make a huge difference. that noise when he pushed on it didnt sound very nice at all. sounds like coil scrape.

 

[edavis.j 10+ year member]

Going by free-air sound vs. in the box I would say that box has a split in one of the seems and the sub is fine unless you keep rubbing the coil on the motor like in vid#2, it hurt watching that like a video of someone clubbing baby seals!

So how am I supposed to push on it then? Just curious?

All the forums I searched on suggested applying a slight amount of pressure, not just a little baby tap, to around the sub to see if it makes a scrapping sound?

 

[edavis.j 10+ year member]

Also...when you guys say tighten up the box...you mean take all the carpet off and tighten up the screws...?

 

[mclerico83 5,000+ posts]

well first off did u order the fi q with high qts or no???? and secondly get a better box custom built for the sub, u would be really surprised how much a quality box changes a sub

 

[edavis.j 10+ year member]

The options I got were: Cooling, P Chamfer, Low QTS, Additional Spider.

Someone is building me a box...they're just taking a while to ship it, so I'm just waiting atm...wish I had it in front of me, but can't do much.

 

[mclerico83 5,000+ posts]

so ur going ported then correct

 

[edavis.j 10+ year member]

yeah the new box is 2cu ft ported

 

[edavis.j 10+ year member]

So after adding some extra screws throughout loose areas of the box....the sound is gone, sounds great again.

So, the problem was indeed the box.

Thanks everyone for the suggestions + help.