wut? you mean yer buyin it used from someone???? If the voicecoils are fryed or are in the middle of being fryed then the sub will only make sound if you press on it or it will make sound but will cut out all the time. And if it is really really really blown it won't have a cone attached to the coils (ya, you guys know who im referring to )

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Vehicle: 2004 Chevy Aveo Hatchback
Battery: Stinger
Wire: W.S. 0 Guage (ground/power strait to battery)
Head Unit: Eclipse CD3000
Speaker Amp: Infinity Reference 7521a
Subwoofer Amplifier: Infinity Reference 1211a
Speakers: Kicker Titanium 5.25"
Subwoofer: Image Dynamics IDQ 15"