Have done some research and found allot of data on free air or infinite baffle subs in home audio. I saw allot of frequency response analysis and people raving about flat response all the way down to 20 hz. Not really boomy but extremely accurate. It appears their is some pretty good information on what you need to build a system and i think it could be applied to my e38. Given the airspace i have found that any speaker will work that has a very low resistance to movement. It think it was an electrical and mechanical total resistance of less than 50. I guess you need something like 10 times the vas of a speaker for the right response. I found a couple speakers that would have the right ratio of vas and compliance and most of them were under 12 inches. Has anyone actually done one of these systems?
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VAS rule is does not always hold true. Just plot them in WinIsd for your trunk's volume and than some - that will give you a good idea. Look for good xmax. Keep in mind, you would need to seal rear deck in your e38, there are bunch of holes there.
Last edited by Mless5; 05-12-2012 at 11:48 PM.
Good pont!
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10x VAS is more of a rule for home audio. Not necessarily needed in car audio. The cabin of a car provides a fair amount of gain in the lower end of the frequency spectrum (rule of thumb is about a 12db/octave slope starting at 55hz). Due to this bump in response (cabin gain) you don't need the amount of low end in an automotive environment as you would in say a large open room like WinISD assumes. In fact a flat response in a large room would yield a bloated low end in a car, but you can always tame that a bit with EQ. So, when plotting in WinISD keep this in mind. I haven't used the program, but I'm sure you can plug in a 12db/octave slope to get an idea of what the response will look like in car.
Usually you want to find something with a low Fs and QTS of around .7. There's not many excellent candidates for IB in a car being produced anymore AFAIK. You're going to want to use as much cone area as possible, so keep this in mind if you want any form of decent output. AE used to produce some pretty sweet IB woofers you may be able to find some used. JBL GTI's are nice for IB with the exception of the ridiculously deep magnet structure. I used to run a pair of Exodus Audio Shiva's IB and loved them. If you can find something like that used it'd be worth looking into. Implementing an IB setup correctly can be easy or difficult depending on who you talk to. It's not as simple as slapping a pair of speakers on a baffle and calling it a day, but I didn't get too carried away with sealing up leaks and was fairly pleased. If you don't have folding rear seats it's the most economical solution for a sub system as far as space savings are concerned.
Best of luck, hope this helps.
Fi IB3 12". $189
It's used by Scott Buwulda. Enough said
www.ficaraudio.com
Last edited by rogan; 05-14-2012 at 02:29 AM.
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actually, scott's were custom "ordered to spec" ib3 18s... but who cares. ib3 is still a great sub the way they typically come.
Benny. You're alive
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yes, but my life's about to end. probably be a dad this week.
Congratulations. Who's the father?
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IDQ's and ID Max's and Acoustic Elegance's all make great infinite baffle subs as well.
Have you heard the ib install? What car? How was it installed? What stood out?
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