# 8" PA midrange enclosure volume suggest.



## nucci (Mar 29, 2012)

(quasi-cross post from build threads, I don't know how many are reading mine)

I'm using BMS 8S215 midranges in an E36 coupe.

My proposed kick design will be right around 4 liters, if it is sealed to the sheetmetal. E36s have rockers which are effectively vented, so if I want a faux-IB install, all I have to do is port into the rocker area.

Modeled IB, the BMS 8S215 has a FS of 88Hz and Q of 0.31. Modeled in 3.7 liters, it has a FS of 175Hz and a Q of 0.60. Which direction should I head, or who should I ask that knows more about this?

Matt


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## thehatedguy (May 4, 2007)

How high are you going to cross them over on the bottom side?


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## nucci (Mar 29, 2012)

I don't know.

Here's the manufacturer curves:










That is in 25 liters. Modeling in Unibox, no matter the volume, the driver starts to roll off pretty fast around 220Hz.

Matt


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## Victor_inox (Apr 27, 2012)

I'd went them into kicks if I have to use these drivers, 4 liters is too low for it.


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## Eric Stevens (Dec 29, 2007)

Vent them into the surrounding cavities and stuff and line the enclosure for best results.

Eric


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## nucci (Mar 29, 2012)

Thanks for the confirmation. I've since decided to do exactly that by cutting a window into the rocker. Using my most conservative estimates the total volume should be at least 30L.

Matt


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## T3mpest (Dec 25, 2005)

I've used these in the kicks and mine were IB into another panel. and they sounded very good. In car you wont' have any rolloff until around 100hz. I actually had too much bass in the 100-250hz area, had to cut as much as 5-7db's off it IIRC. Ended up crossing over at 120hz, but only because my subs could mate that high.. They did 80hz at 24db/octave at moderate/loud volumes fairly well.. Only when I went very high on the volume knob was that ever a issue.


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## thehatedguy (May 4, 2007)

I thought you had the neo bms 8s?


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