I was helping my friend out today wire 2 12" jls and we got everything setup and things were hunky dory. We took them from his old car, built a new box and tossed them in his new car. We powered it on (using multimeters to measure gains and SSF beforehand) and we started playing some tunes. All is well but I go to turn the volume down low to where the sub is barley playing and I noticed some scratching noise. I went back and pushed on the magnet (power off of course) and no scratching, no huge resistances... about the same as my 15. We took out the subs and they look fine. No bent coils (as far as I can tell), nothing is stuck, no burning...I took a quick peak at the terminals (we used screws in the wood for + and -) and they are pretty loose. Could that be the problem? Or maybe not a good enough ground? I don't think this sub is blown but I think something is definitely wrong.

I think lose terminals could definitly be the problem. Just tighten them u. And see if it still hapens

Could it be blown even with no resistance while pushing in the magnet manually?

Could it be blown even with no resistance while pushing in the magnet manually?

You mean pushing in on the cone right? And yes, very much so, but not necessarily blown. I've seen many times where a tinsel lead goes bad and it causes problems such as that. I think bobobass has the right idea tho, tighten the terminals first then see what ya got. If it still does it push in on the cone while its playing and see if it stops and starts again. If it does then the chances are it's a bad tinsel lead.

You mean pushing in on the cone right? And yes, very much so, but not necessarily blown. I've seen many times where a tinsel lead goes bad and it causes problems such as that. I think bobobass has the right idea tho, tighten the terminals first then see what ya got. If it still does it push in on the cone while its playing and see if it stops and starts again. If it does then the chances are it's a bad tinsel lead.

Yes pushing on the cone, sorry.

Isnt it bad pushing on the cone while its playing? I know not to do it at like full power but couldnt that make the magnet come in contact with the coils?

Also, does anybody know what to look for? I am going to pop the woofer out again tomorrow to see if I overlooked anything. Nothing looks bent compared to mine.

ya'll built a new box b4 putting them in the new car right? its possible that it could be the box itself making funny noises if it has a slight air leak. pull subs out of the box and play them free air and make sure its the subs. my 15 makes scary noises at me when my ssf is to low. but it does it on higher bass notes with minimal excursion which makes no sense. lol. a ton of ppl said is it the box? which its the sub cause it does it free air.

could also be something down in the motor between the coil and pole piece.....its amazing how tiny things affect subs

lol, well, I didn't mean to shove it all the way, or while there's a lot of power on it. Usually with a bad tinsel lead it doesn't take much to get it to do it's thing, just loud enough to hear it and just pushing enough to move the cone and see if it cuts out or not. The coil won't rub the gap unless you push down on just one side of the cone or something like that to cause it to twist.

If you want to be sure the coil(s) aren't blown the best way to check is to use a DMM, which would also work to test the tinsel. Use the DMM to check the resistance of the coil. The DC resistance will be just a little lower than the rated impedence (example: 4ohm sub will show 3.x ohms DC resistance). On the tinsel check if the resistance changes then there's a good possibility a tinsel lead is damaged and most likely you won't be able to see that problem either. There's not alot of things to see on a sub that could possibly be blown without any major signs, but one tell tale sign could be the color of the coil IF you can see it through the vents in the frame. Usually the coils will be a darker copper color, almost red looking when they're good.

Hopefully you have access to a DMM, it will tell you more definitively than about any other check.

If you want to be sure the coil(s) aren't blown the best way to check is to use a DMM, which would also work to test the tinsel. Use the DMM to check the resistance of the coil. The DC resistance will be just a little lower than the rated impedence (example: 4ohm sub will show 3.x ohms DC resistance). On the tinsel check if the resistance changes then there's a good possibility a tinsel lead is damaged and most likely you won't be able to see that problem either. There's not alot of things to see on a sub that could possibly be blown without any major signs, but one tell tale sign could be the color of the coil IF you can see it through the vents in the frame. Usually the coils will be a darker copper color, almost red looking when they're good.

Sweet. I didnt even think about using a DMM. I assume if its bad it will show something lower than 3.x (assuming its a 4 ohm). Or higher? Or nothing at all? Is there anything else that may be if those show all good?

Well PROBLEM SOLVED! It was shitty soldering that did it. Well its not really solved but I am looking for something different besides using screws to carry the power through the box wall -- something that has a positive and negative terminal on it and its like something you put in the wall to the box.. I cant explain it better than that. My old old old system that I bought from a "we put it in your car" type store tossed one of those on. I just cant remember what they are called - it usually has red and black knobs on it that you can either screw in to hold the wire in place or its spring loaded.. I searched for about 45 minutes at the hardware store here in Madison but dont remember nor could I find one close.. Any suggestions on what I am trying to remember (or what they are called) would be sweet!

EDIT:

look at the picture on this page.. You see the red and black spring loaded switches on the back? thats what I am looking for

Edited July 29, 201015 yr by Hell-Razor

http://www.parts-express.com/wizards/searchResults.cfm?srchExt=CAT&srchCat=417

http://www.parts-express.com/wizards/searchResults.cfm?srchExt=CAT&srchCat=417

YES! Thank you soooo much. I was racking my brain for the past half day trying to remember what they were called.