Sub question

[csl2006]

Alright this goes back to when I had my camaro and my system. I used to have a 15" audiobahn alluminum faced sub. It was a .5ohm sub. Peak power was 2100w. Rms was 1000w. Running off a Phoniex gold 1500w amp. Well before I sold it to my buddy it started having a pinging noise everyonce in awhile but didn't lose power. It hit good etc. He's in arizona for college and Im thinkin about buying it back off of him for the s10. I checked the rubber seal around the facing and it wasn't blown or no cracks. The pings weren't constant either. any ideas what it could of been?

[droopy89]

this might be completely different, but i had a set of Infinity speakers a while back, they did this. But it was more like a ping/scraping/scratching sound. A local car audio shop guy told me the voice coil was off center. So, that could be it. Just a thought

[csl2006]

it wasn't making a scraping or a scratching sound. It wasn't a high pitch ping either. It wasn't on the songs I was playing because I cancelled out the sub on the unit and listened to the song over and over and there was no pinging in the song. could be it but. I shaved the box down a little bit also. I know you have to have the right size box for the sub inclosure but someone said it could make it do that. but it wasn't doing it constantly.

[Mikz86TA]

Its a .5 ohm sub? Ummmm...Not unless its blown.
Sub voice coils are 8, 4 or 2. Some have dual voice coils which are two 4s or two 2s usually. Wiring them together in series or parallel will change what the amp sees. Its like having 2 subs in one.
If you wire two 4s in series it will be 8, in parallel it will be 2.
If you wire two 2s in series it will be 4, in parallel it will be 1.33.
A blown sub can still play. Using a digital voltmeter and finding out EXACTLY which voice coil setup it is and how its wired is the 1st task.
That will tell you if its wired right and its condition.
Secondly, there are only MONO amps that are capable of sustaining a 2ohm load. Stereo/2channel amps are only 2ohm stable in stereo NOT mono/bridged. ANY amp pushed to the lower limits of resistance will have more distortion output as a result. Most distortion is inaudible in subs. If its a amp that has alot of THD% at 4ohms (which most are rated at this resistance tho they go lower), then at 2 ohms you can almost double that figure.
If it was say a DVC 2ohm and its parallel, then the amp sees 1.33 ohms at rest. Ohm load varies during playing of a driver. Subsequently the 1.33 ohm is less than even a mono amp is 'stable' of running. In trn your amp is being overdriven. There are only a handful of car audio amps that are 1 ohm stable anyways.
The noise could be seperation of the voice coil or the voice coil former coming loose. Heat from playing for a while can also distort the coil if it has an aluminum former. All can cause noises similar but not limited to the ones discribed.