Sub Testing

Sorry this is going to be such a newb question but here it goes. I bought an 8" JL w0 from ebay and i was testing it today with no enclosure just basically sitting on my seat. At a very low level it started distorting. I thought instantly ok this is a used sub its blown. I have the right amount of power and everything going to it. Now i get some feedback from some co workers that i NEED an enclosure to test it and that is why it was distorting. True? Sorry for the stupid question, i appreciate the help. does anyone have any experience with the w0? any good?

A simple test would be use a meter and check the impedence or ohms. And when you do check this keep in mind that the actaul read out will be slightly different than what is listed on the woofer

for example if you have a 4 ohm woofer and you check it with the meter, the meter might read something like 4.3 (even more or less), so don't be too concerened unless it jumps around then you may have a blown woofer

Does the woofer feel "tight" or have some resistance to it when you GENTLY psuh on the cone?

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Don't destroy your sub as soon as you get it!  Stop playing around and build a proper enclosure for it.  Then you can test it.  A subwoofer in free air (as you described) will not tolerate very much power applied to it because there is no enclosure damping factor to control the cone.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Thanks guys, when i push the cone it is fine. Stevdart i understand what your saying, but should the sub distort at even an extremely low level? Its really not like I'm blasting the music at all its barely evening listening level. it just makes this plastic hitting noise, i dont know im very uncertain

You should mount it in some type of enclosure to be sure.  I've run subs free air before but paying strict attention to the amount of power they get and using a test tone at Fs Hz.  As dwarren said, just pushing with your fingers on the cone, in from the front side, out from the backside, should give you an indication that there is a problem with it.  It should move with no sound (no hookup to power, please) and move back out on its own.  If you have scraping noises or the cone won't move, the sub is shot.

But you said when you push on the cone it is fine.  So build an enclosure, then. 

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

alright, I think I'm going to head over to my local shop tommarow and pick up an enclosure and than return it after testing. Hate to do that but i need to know now if this sub really is working. any opinon on this stev. Infinity Refrence 840w vs the JL audio 8w0? which one would you go with?

Don't just buy any enclosure just for testing, you want to have one that's right for the sub.  As with any speaker, your ears should be the judge.  Find dealers who carry the lines and give a listen.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.