Author Topic: Sub box dimensions/design  (Read 1903 times)

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Offline e13tankbuster

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Sub box dimensions/design
« on: March 07, 2014, 07:31:18 pm »
Anyone on here good with sub enclosure design? I have a few questions with regards to internal dimensions that are specific to the subs I have and port length.

10" Alpine TypeX
Vented box volume range: 0.8'-1.5'
Optimum:
External box dimensions: 12.5"x14.5"x18.5"
Gross internal volume: 1.4cu'
Vent area: 11sq" (11"x1")
Vent length: 22"
Vent displacement: 0.24cu'
Net internal volume (Vb): 1cu'
F3,ripple,Fb (I have no idea what this is, sumn to do with port tuning I think): 29hz, 4.7db, 36hz

Question: The above optimum box is 1.4cu', I would like to scale this down a bit but I cant figure out the port size. I've tried couple online box generators but cant make sense of the numbers. The design keeps giving me a port length that is waaay longer than what the actual dimensions of the rear of the box calls for.. eg a 28" long port but a 12x14 box design. Maybe I'm entering the wrong tuning value..I dunno..

Any car audio experts out there that can help me out?
Thanks
EVL STi: http://www.westernsubaruclub.com/smf/index.php?topic=39740.0
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Offline jvd

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Re: Sub box dimensions/design
« Reply #1 on: March 09, 2014, 07:04:12 pm »
As you decrease the size of the box the port length will need to increase to keep the same tuning frequency.

Fb is the tuning frequency of the enclosure. F3 is the point where the response is down 3db. It gives you a good idea of how low the speaker will play until output starts to drop off. F3 of of 29Hz is digging pretty low. Lots of low end output.

Usually an F3 that low is not necessary in a car because of cabin gain... although it's always better to EQ some low end output out of the response than not have it in the first place.

I've had good success with subs designed for small sealed enclosures in automotive applications. I'm not a huge basshead though.

Just did a JL 13TW5, for a friend in, the recommended .80cu ft and it had plenty of output.

Offline GlennC

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Re: Sub box dimensions/design
« Reply #2 on: March 10, 2014, 10:10:48 am »
www.the12volt.com has some good port length calculators. Play around with port width and height and it will help you get it to dimensions that will fit your box.  You can always run your port around the back of the box to gain length too, just make sure you have smooth transitions or you can end up with port noise.
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Offline e13tankbuster

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Re: Sub box dimensions/design
« Reply #3 on: March 10, 2014, 10:15:54 am »
^^thanks. Yeah I posted the question on 780 as well and that's the answer I was given there too...

Starting to think that I want a little fancier box than a regular old rectangular one.. Maybe delve into the fiberglass setup..

Anybody ever do a fiberglass enclosure?
EVL STi: http://www.westernsubaruclub.com/smf/index.php?topic=39740.0
Hey, lazy, read the first friggin post in this thread.
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Offline GlennC

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Re: Sub box dimensions/design
« Reply #4 on: March 10, 2014, 10:18:04 am »
I've done a whole whack of them. They are much harder to get tuned correctly due to the fact the dimensions cant just be entered into a calculator that will spit out port dimensions.
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Offline e13tankbuster

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Re: Sub box dimensions/design
« Reply #5 on: March 10, 2014, 12:17:28 pm »
Now because I have two of them, when it comes to tuning I assume that it is imperative that they be tuned identically to avoid adverse sound issues?
EVL STi: http://www.westernsubaruclub.com/smf/index.php?topic=39740.0
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Offline GlennC

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Re: Sub box dimensions/design
« Reply #6 on: March 10, 2014, 12:19:02 pm »
If you're building two seperate enclosures, it's very important they are identical.
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Offline e13tankbuster

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Re: Sub box dimensions/design
« Reply #7 on: March 10, 2014, 12:26:32 pm »
Aaaaaaand now I'm back to building an mdf box lol
EVL STi: http://www.westernsubaruclub.com/smf/index.php?topic=39740.0
Hey, lazy, read the first friggin post in this thread.
Custom air and audio by Powersource Performance