# Single 12" 4th order. Ski pass port in my BMW M6. Help?



## timmay77 (Jun 21, 2010)

I am looking to do a 4th order single 12" box in my 2016 BMW M6. The car already has the Bang and Olufsen sound system which has 2 under seat woofers that do fairly well. I just need something that gets SUPER low and has some more volume. The under seat woofers do not do well under 45hz.

I have tried using several different software programs, but I just do not have enough knowledge to understand what I am doing. Will the box be too big for what I am trying to do? I have a 2014 BMW 328 as my daily that I put an American Bass XFL1222 in a 2 cubft ported box tuned to 35hz in to. Skar 1500 watt amp. IT does very well. I was just hoping for something more refined for the M6. I really like the XFL woofer. It really performs.

Any help?


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## Bayboy (Dec 29, 2010)

Exactly what aspect of 4th order are you having problems with? While 4th order bandpass can sound decent, not all subs work well with it. 

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## timmay77 (Jun 21, 2010)

Bayboy said:


> Exactly what aspect of 4th order are you having problems with? While 4th order bandpass can sound decent, not all subs work well with it.
> 
> Sent from my SM-G986U using Tapatalk


I honestly have no idea how to formulate what size the chambers need to be, port size, basically none of it. I have software that can calculate ported enclosures and sealed, but not 4th order.


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## Bayboy (Dec 29, 2010)

I haven't used WinISD in years, but I do recall it being a bit easier with custom 4th orders albeit any bad results are on the user. I currently use BB6 Pro, but my hard drive crashed so I'm out of commission for a bit

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## EmptyKim (Jun 17, 2010)

Someone did two AudioFrog (GS or GB) 10s or 12s in 4th order on this board. Said they worked well. Box was nice.


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## skylineqrt4 (Jun 1, 2009)

Have you thought about going IB with something from acoustic elegance?


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## Bayboy (Dec 29, 2010)

IB is a good option and much easier to construct. If you still want to go the bandpass route, I'd employ the use of a good installer or at least a box designer/builder since your knowledge of bandpass is very limited. Just be ready to resort to the use of a different sub if needed. 

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## timmay77 (Jun 21, 2010)

skylineqrt4 said:


> Have you thought about going IB with something from acoustic elegance?


I've used IB in the past and did not care for it at all. I am going for the extreme low end of the spectrum, IB wasn't even on my mind.



Bayboy said:


> IB is a good option and much easier to construct. If you still want to go the bandpass route, I'd employ the use of a good installer or at least a box designer/builder since your knowledge of bandpass is very limited. Just be ready to resort to the use of a different sub if needed.
> 
> Sent from my SM-G986U using Tapatalk


I have reached out to several designers, I either do not get a response, or they just offer up s standard slot ported box instead of answering my 4th order questions. 

Using a different sub isn't a problem. I only suggested that sub because of how well it has performed in my other car.

I guess I am surprised there isn't someone on this forum that could help with a formula or something to help figure this out. Is 4th order really that complicated? I can't find that much information on the interwebs. Odd.


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## Bayboy (Dec 29, 2010)

Yes and no. 4th isn't that complicated, but knowing your car's acoustics can be a big help, or at least some experience in which ratios will work best. WinISD is a nifty tool when it comes to designing 4th orders because it's easier to vary the chambers & port to get the desired response. BB6, not so much though it can do it along with entering in the acoustics.. 

If you can get a copy of Vance Dickason's LDC, you'll find the the ratios and resultant response. 

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## miniSQ (Aug 4, 2009)

single 12 4th order bandpass build


First things first, I am a newbee. O k so I tried to build my first bp box with port into center armrest of my sedan. I know that most boxes built anywhere from 4 to 1 to 1 to 1 port to sealed. I plugged my 12 inch alphasonik 700wrms specs to a couple free online bp calculator and it put out...




www.diymobileaudio.com


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