springy sound

I just got in my Alpine SWR-1221D from e-bay. I installed it as soon as I got the package. Every time the sub hits there is this spring sound that comes with it. It sounds like a loose spring vibrating inside of the enclosure. I removed the sub and checked out the box, it was empty, i even took the hose attachment from my vaccume to see if it would pick anything up. I put it in again and i get the same noise.

This noise if not comming from vibrations anywhere in the car, but from the actual sub. I sent a nasty little e-mail to the company that I got it from (Dint Trading) and i'm waiting for a reply.

My question is if they won't do anyhting about it what can i do to get rid of that noise?

If it helps its an Alpine SWR-1221D w/ the DVC wired in serries to have 4ohms. This if bridged to a rockfor fosgate 360.2 amp.

Thanks a lot

Pull that speaker from the box and set it up again to play.  Position it so you can watch everything it does when it hits.  Sound is either from sub or box, this will isolate that.  A way to do this is to hang the sub in free air, hooked through a mounting hole.  You'll have to set something up at the car trunk to accomplish this.  Make sure the amp gain is set correctly before removing the speaker, and play low freq music with some variety like Bass Mechanik or something.  Adjust the frequency crossover on the amp while you're testing to see if the sound is at lower or higher freqs.  You may even unplug the RCA's to the front speakers so you can hear things better while you're troubleshooting.  Post what you see and hear.

I forgot to mention. If i tap my finget on the cone of the sub (Where it says "Alpine Type-R") i can slightly heat this sound. The gains i left alone from a previous sub (MTX 6000 12").

I'm in school right now so I can't go outside and test all of this ... but I definitly will tonight or tomorro (depending on how my minor foot surgery goes tonight).

I was thinking that it was something wrong with the meal mesh stuff that is behind the cone. Is that possible?

Sounds partially blown to me, was it used when you bought it?

When you tap the type-r symbol, the shouldn't be any viberations, , just a quick sound  like slightly knocking your knuckles on your desk.   if it makes a ping and lasts like a second then theres something wrong.

Yes it as used and i think you are right after i did what stevdart said.

First i have a question about how to set gain properlydon't you take the SquareRoot(amp Voltage * sub Resistance) then play a test tone and use a DMM to set the gains so that the DMM reads that number?

I took SQR(360*4) ~= 37.9

I then hooked the pos of the DMM to the pos of the left channel then i took the neg of the DMM and hooked it to the ned of the right channel. I did this with the volume at 35 (max volume = 50) Then with the gain all of the way up i only got 28 on the DMM.

I hooked up the sub free air and played the Audio slave CD. there was definitly that sound every time the subwoofer made a noise. low and high frequencies. When looking behind the cone everything seems to be in order and the sound seems to be located inside of the sub.

Was this Dint Trading an online company by chance?

Ravenndude

How did you come up with the multiplying factor of 4? If I have two 4ohm DVC and each sub is set up in parallel for 2ohms each in stereo and the amp is 250 watts per channel RMS, do I take the sqare root of 500*2 or 4? Or do I take the square root of 250*2 or 4 and just measure one channel with the DMM.  Also, where would I get a test tone CD?