subsonic filter?

[IMPP 10+ year member]

I was told that the jbl 1200 doesnt have a subsonic filter, and that i shouldnt use it because I have a ported box. But why would it be diff. in a ported box than in a sealed one, and would it be ok to use it?//content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

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[ramos 5,000+ posts]

Depends upon the tuning frequency of the enclosure for ported. A subsonic filter cuts frequencies below 20hz. Any idea what frequency yours is tuned to ?

 

[IMPP 10+ year member]

I'm not exactly sure, but i can probably find out because its a virtual technology box, and a lot of stores around here carry them. So I could probably just go ask around.

 

[IMPP 10+ year member]

What happens when it goes below 20 hz. Will it mess anything up?//content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

 

[chris229 10+ year member]

a subsonic cossover can be made to cut any freq not just 20hz. If you play your sub below tuning freq the sub will decouple or unload from the air. This causes it to act like it's not in a box. The cone movement will no longer be controled by the air

 

[dkguitarist 5,000+ posts]

i kno this is an old thread (2002 was the last post). but i had a question related to this topic and didn't want to start a new thread. anyways, as you guys kno, the L7's can be used in a box or free-air. with that said, i have my L7's in a vented box, and i've read about using a subsonic filter on a ported box to filter out harmful frequencies that causes the sub to act likes it's not in a box. but since the L7's can be used free-air, how would this be harmful to them? juzt wanting to kno. thanks.

 

[dkguitarist 5,000+ posts]

anyone?

 

[jtomsic 5,000+ posts]

L7s can be free aired? news to me.

 

[JimJ 5,000+ posts]

with that said, i have my L7's in a vented box, and i've read about using a subsonic filter on a ported box to filter out harmful frequencies that causes the sub to act likes it's not in a box. but since the L7's can be used free-air, how would this be harmful to them? juzt wanting to kno. thanks.

no sub should be run truly "free-air", unless you're testing it or something. I think you're confused with infinite baffle, which really is seperating the rear and front waves of the sub, just making the sub think it's in free space.

When you play low notes below tuning, the enclosure no longer provides any control over the suspension, so the sub has the potential to "unload" and play uncontrolled - this is very bad, no matter what sub it is. If you play 18Hz test tones to an L7 enclosure tuned at 45Hz, the sub will not like it - not one little bit.

Get a SSF.

 

[ANeonRider 10+ year member]

http://forums.caraudio.com/vb/showthread.php?t=75474&highlight=subsonic

All you need to know about subsonic filters....

 

[dkguitarist 5,000+ posts]

my bad. i was thinking of the solo-x or something similar or probly infinite baffle. i'm human. we all confuse things sometime or another. you're right tho, the L7's aren't free-air. and thanks for clarifying on the ssf. i feel dumb.