Subs scratching and popping

[lean]

I searched for a while and didn't find much, so I'll pick your brains.

I have a pair of 12" dvc alpine type-r's sittin around for about a year and finally got around to building a new box for my daily driver. Amp is a mono 600w JBL. I'm using the stock Jetta deck and getting my amp signal from the rear speakers. The subs are wired like this:

The left sub makes a frequent intermittent popping noise when playing. I've tried a couple grounding points and it doesn't help. The subs just don't sound nearly as loud as they should be. I've played with the gain, lpf and boost and nothing helps.

Both subs make that rubbing/light grinding/funky noise when pressing the cone in (while the amp is off), but I'm almost 100% sure they have always done that. The left sub also makes a farting noise when playing. I've found if I apply moderate to hard pressure to either cone while they're playing, the bass gets MUCH louder and cleaner.

I'm not sure why they aren't working well now, as the last time the combo was used it all sounded very good. //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

Any tips would be appreciated. Maybe I'm overlooking something?

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[squeak9798 5,000+ posts]

Sounds to me like one if not both are blown, or atleast on their way to the grave.

Stick a DMM on the voice coils and see what resistance they read.

 

[lean]

bummer. its like there wasnt a problem last time i used the setup. that was with a different box, car and deck though. hmm. i may try to run a set of RCA cables from a roommates car to see if the high level inputs are whats screwin with it. ill have to dig up my DMM and give that a shot too.

 

[nwo504 10+ year member]

yea they are on their way to the grave i had that problem now my l5 is gone but my l7 arrives today!

 

[lean]

Is there anyway to visually inspect the voice coils for damage? I was in to car audio a lot more a few years ago and don't have the budget to pick up a pair of good new subs.

 

[radel2dope 10+ year member]

Im gunna go with the fact that they are blown, same thing happened to my speakers, if you apply pressure they play, so unless you hire a midget to push on em all day, you need new ones.

 

[lean]

lol.

****it. these ****ers boomed like it was no problem the very last time i shut em down a while back and now they wont play for shit. //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

as far as what squeak said, do "blown" VC's have an abnormal resistance reading?

 

[squeak9798 5,000+ posts]

as far as what squeak said, do "blown" VC's have an abnormal resistance reading?

Yes. When you measure the DCR of a coil, it should be below (but relatively close to) the impedence of the coil. If it is drastically different (like, 0 or close there to), then it's blown.

 

[stangme01 10+ year member]

yeah sounds like a major problem man.