Eric's85TA

iTrader: (4)

I have a single JLW012 4ohm sub in a sealed box. I am running it with a Crossfire cfa202 amp rated at 200watts rms. When the sub hits, it doesn't seem to be really solid; the sub doesn't seem tight, it flops around just a little bit. Somebody told me that if I would get a better amp, the sub would hit hard and solid with no wavering. I was thinking Rockford, Kicker, Kenwood. Do you think this would help? Any suggestions, model numbers? If you don't understand my problem I'll try to reword it.

KlayBuRn

whats the sub rated at RMS?

Eric's85TA

iTrader: (4)

The RMS rating is 125watts, but i have been told by several people that those JLs can easily handle 250.

bigvic

You might want to check for leaks on your box. From your description it sounds as though your sealed box is not sealed good enough. If I recall correctly, I read somewhere that if you push in on the sub as far as it will travel (while the stereo is off of course), that it should take about 7 to 8 seconds for the speaker to fully rebound in a good sealed box. I dont know if this is fact or not, but I have built all my boxes to that tolerance, and the ones that pass that test sound a hell of a lot better than the ones that dont. I dont know if this is your problem or not, but all the airtight boxes I have seen and built dont allow the speaker to flutter or wave excessively no matter what amp was used, because the pressure inside the box holds the speaker tight. Hope this helps and makes sense.

vic

Eric's85TA

iTrader: (4)

Hey thanks man. That could very well be the problem. Do you think I should rebuild the box, or is there some way to better seal it.

dallasiroc

Caulk the hell out of it before building another box. can also try som double sided weather stripping between the basket and the box to seal around the speaker, alot of times air escapes at this point.

Eric's85TA

iTrader: (4)

I did build it out of 3/4" particle board and not MDF, because i couldn't find any. Could this be contributing to the problem? Thanks alot for the suggestions. When I get home this weekend I'll have to try to get it sealed up better.

bigvic

Using particle board instead of MDF most likely will hurt the sound quality to a degree, but since you already have the box built, do as the others have said and silicone the hell out of the seams. Take your speaker(s) out and put a nice wide bead of silicone on every joint. Then smooth out the bead by running your finger over it which also helps to pack it into the crevasses of the joints. Don't be stingy with the silicone. This is one instance where I believe that more is better. Then make sure you let the silicone dry over night before you install your speaker(s). After the silicone is completely dry put your speaker(s) back in the box. Make sure you use a gasket of some sort whether it be the box's carpet folded in around the speaker hole or you can use some weatherstrip tape, or you could even make a gasket out of gasket making material. Just don't silicone your speaker(s) into the box unless you never want to remove them. I think it also makes the box gheto looking, although in my younger misinformed days I did that for a quick fix. I ended up regretting it later. Just make sure you form a seal between the speaker's basket and the box. When you think it is air tight use the test I mentioned above. If you can make it take about 7 seconds to rebound, you will be quite pleased with the results. If it takes about 1-2 seconds check for leaks in a quite room while repeatedly pusing in on the sub.

Regarding the use of particle board instead of MDF; you might could throw some polyfill inside the chamber to soak up some of the extra ressonance associated with the parcle board. Unless your box's volume is smaller than the recommended minimum for your speaker, I would probably use about half a pound of poly per 1.0 cubic foot of airspace. If your box's volume ended up less than your speaker's specified volume amount, then use 1 pound of poly per 1.0 cubic foot. Hope this helps and good luck. Just remember not to do it half-assed or rushing it, or then you will get to do it over again down the road.

Vic

[This message has been edited by bigvic (edited March 13, 2001).]

Belker

I agree .... its probably the box and not the amp.

Polecat

To test the box, push the woofer in, and if it comes right back out pretty quick, there is an air leak. You want the woofer to return slowly.

Eric's85TA

iTrader: (4)

You guys are great! Thanks for the help and saving me what I might have spent on a new amp.