infinite baffle (free air) subs... do they need to be sealed on the back side?
06-02-05, 10:16 AM
#1
infinite baffle (free air) subs... do they need to be sealed on the back side?
I'm running a JL IB4 sub in place of my stock on my 92 SC... and while the inside cabin is sealed... the trunk area (and for those that don't know... the SC's trunk is completely sealed) my trunk area is no longer sealed.
Will this affect the way the sub sounds?
The SC's trunk on the sides come with this plastic box contraption that acts as a 1 way check valve. I had to take those off and now if someone where to get locked in my trunk... they won't suffocate cuz air is free to move about my trunk now.
Will this affect the way the sub sounds?
The SC's trunk on the sides come with this plastic box contraption that acts as a 1 way check valve. I had to take those off and now if someone where to get locked in my trunk... they won't suffocate cuz air is free to move about my trunk now.
06-03-05, 11:15 AM
#2
Great question. No, does not need to be sealed.
The goal of IB setup is to completely separate the woofer's front wave from its rear wave. As long as the rear-firing wave can't propagate back into the cabin, you're good to go. There is no requirement for an IB speaker to have resistive air pressure behind it to control its excursion, that's why every speaker cannot be used for IB - most speakers are meant to live in a box, where the air inside provides a resistance to speaker cone movement and works in conjunction with the speaker's suspension. (This is what all the Thiele-Small parameters are about when you do enclosure designs.) This is also why you can't put a speaker unenclosed in mid air and try to play decent sounding music. The front and rear firing air waves interfere with each other and make a mess.
In your trunk, your rear deck is the baffle, and that should be reasonably well sealed. The holes in your trunk may change the response very slightly, but not enough to be concerned with. One thing you may find is that because of the holes, the air doesn't vibrate the rear quarter panels as much, and because this vibration sometimes can propagate to the front of the car, you may feel that the bass may not rumble as much, but this tends to happen with larger woofers than 10IB4.
Hope that helps.
The goal of IB setup is to completely separate the woofer's front wave from its rear wave. As long as the rear-firing wave can't propagate back into the cabin, you're good to go. There is no requirement for an IB speaker to have resistive air pressure behind it to control its excursion, that's why every speaker cannot be used for IB - most speakers are meant to live in a box, where the air inside provides a resistance to speaker cone movement and works in conjunction with the speaker's suspension. (This is what all the Thiele-Small parameters are about when you do enclosure designs.) This is also why you can't put a speaker unenclosed in mid air and try to play decent sounding music. The front and rear firing air waves interfere with each other and make a mess.
In your trunk, your rear deck is the baffle, and that should be reasonably well sealed. The holes in your trunk may change the response very slightly, but not enough to be concerned with. One thing you may find is that because of the holes, the air doesn't vibrate the rear quarter panels as much, and because this vibration sometimes can propagate to the front of the car, you may feel that the bass may not rumble as much, but this tends to happen with larger woofers than 10IB4.
Hope that helps.
Last edited by engin_ear; 06-03-05 at 11:20 AM.
06-03-05, 11:35 AM
#3
thank you... very informative and was along the lines of what i was thinkin
yea... the front wave should be completely sealed from the rear wave... its just that my rear wave wiill no longer be in a sealed environment.
What i should have thought about doing to test this out was listen to my stereo with my trunk open... duh!
yea... the front wave should be completely sealed from the rear wave... its just that my rear wave wiill no longer be in a sealed environment.
What i should have thought about doing to test this out was listen to my stereo with my trunk open... duh!
Thread
Thread Starter
Forum
Replies
Last Post
heyarms
IS - 2nd Gen (2006-2013)
19
08-07-12 08:11 PM
