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need to build a sub box.

  #1  
Old 07-25-2011, 06:59 PM
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Question need to build a sub box.

i have been looking around and around and around.. i need to build a sub box for my 2 new alpine 12in type Rs.. not sure on what size to do. i would like to mount them inverted. but i dont know what dimensions i would be looking at for the new box.. any help. i know how to find Cubic feet.. but idk how much i need.. i have toyed with a few dimensions but dont know exactly what size i need.. if someone could tell me that would be awesome!
 

Last edited by Boxman420; 07-25-2011 at 07:08 PM.
  #2  
Old 07-25-2011, 07:31 PM
Join Date: Dec 2010
Location: Nebraska
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There is a program named winISD that you can download for free. I havent played around with it at all but from my understanding you can plug into the software what kind of sub you have and it will give you the best dimensions. Then you can change the box to fit your trunk how you want and it will tell you how the frequencies will change.
 
  #3  
Old 07-25-2011, 07:32 PM
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....come on man google ffs.

the type R wants 1cf-1.25cf. far as shape, sealed box, shape isn't as important. the factors that change how a good box are, the proper volume and how well they are deadened, double 3\4 will leave you with a very nice sounding box. but double half inch front baffle should be enough.
 
  #4  
Old 07-25-2011, 07:46 PM
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i have used the winISD program.. i understand how much 1 sub needs.. my question is does it change for 2? basically i just double that? so if i had a 2cf box then thats what i need.. also im inverting the subs so maybe drop it down to 1.9?
 

Last edited by Boxman420; 07-25-2011 at 07:48 PM.
  #5  
Old 07-25-2011, 08:02 PM
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yes, double it. i would do 2.4 or something to compensate for displacement. that way you'll probably be around 1cf per sub.
 
  #6  
Old 07-25-2011, 09:11 PM
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In my honest opinion, WinISD is not for the person that doesn't even know how to find the specs of his subs. That's not a jab at you Boxman, but I know that program was way too advanced for a beginner like you, it would just confuse you even more.

Ever heard of google? There's tons of good info to be found there and sure beats waiting however long it takes to get a response here. I'm not saying don't ask us anything but c'mon man, at least try to find the info. Now that i'm done busting your *****, lol, box size is a spec that the manufacturer provides along with all the other specs of the sub. So a good place to start to find the info you need is to do a google search for "type r 12 specs".

According to Alpine, the optimum size ported box is 1.5 cubic ft., so two subs would need 3 cubic ft. total, after displacement of the subs/port/bracing. Optimal sealed volume is .65-1.25 cubic ft. each, again after displacement. Displacement is the amount of airspace taken up by anything added to the inside of the box, like the sub, the port, and bracing you might do (most commonly 45's),etc. You can find the displacement of the sub with the other specs Alpine provides. So for example, if the displacement of your subs is .18 cubic ft. each, just the subs alone would displace .36 cubic ft. of airspace just by themselves. So if you designed your ported box to be 3 cubic feet and didn't factor in the sub displacement, once you throw the subs in there it will change things, you'll have less volume at 2.64 cubic ft. and it will effect your tuning as well. Same for a sealed box, if you designed your box to be on the small end of things at 1.3 cubic ft. for the pair, adding the subs will now make your box .94 cubic ft.

My suggestion would be to build a 3 cubic ft ported box with a L port, tuned to 34-36Hz. If you plan on flush mounting your subs, a double baffle would be necessary, otherwise it would be a waste of time and money. I mean, it's not gonna hurt anything by doing it but for 2 12's on 1000 watts I just think it's overkill. And if you did go that route you'd have to make sure to accomodate for the extra baffle on your box plans cause it changes displacement a bit if you don't flush mount and adds some length to your port as well. Lastly, don't use anything other than 3/4" material, either MDF or Birch, whatever you can afford. Birch would be the better of the two but it's also a bit more expensive.

As for inverting your subs, the only difference that will make is less displacement inside the box. So if your subs displace .18 cubic ft. each, you'd have to build your box .36 larger than what you really want to end up with if you mounted them regularly. Inverting them would allow you to build the box to exactly the spec you want cause the subs are not taking up airspace inside of it. If your box is ported, you'd still have to account for port displacement though. Whatever you do, DON'T GUESS WHAT YOUR SUBS DISPLACEMENT IS and build your box according to your guess. Find out exactly what it is.
 

Last edited by Milhouse; 07-25-2011 at 09:16 PM.
  #7  
Old 07-26-2011, 01:42 PM
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no offense taken at all. iknow my noob status at this stuff.. just trying to learn. i found the specs and everything along with box sizes for just one but i was making sure you just double it before i build a box. im gonna use 3/4 MDF most likely.
 

Last edited by Boxman420; 07-26-2011 at 02:52 PM.
  #8  
Old 07-26-2011, 02:30 PM
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Originally Posted by Milhouse View Post
In my honest opinion, WinISD is not for the person that doesn't even know how to find the specs of his subs. That's not a jab at you Boxman, but I know that program was way too advanced for a beginner like you, it would just confuse you even more.

Ever heard of google? There's tons of good info to be found there and sure beats waiting however long it takes to get a response here. I'm not saying don't ask us anything but c'mon man, at least try to find the info. Now that i'm done busting your *****, lol, box size is a spec that the manufacturer provides along with all the other specs of the sub. So a good place to start to find the info you need is to do a google search for "type r 12 specs".

According to Alpine, the optimum size ported box is 1.5 cubic ft., so two subs would need 3 cubic ft. total, after displacement of the subs/port/bracing. Optimal sealed volume is .65-1.25 cubic ft. each, again after displacement. Displacement is the amount of airspace taken up by anything added to the inside of the box, like the sub, the port, and bracing you might do (most commonly 45's),etc. You can find the displacement of the sub with the other specs Alpine provides. So for example, if the displacement of your subs is .18 cubic ft. each, just the subs alone would displace .36 cubic ft. of airspace just by themselves. So if you designed your ported box to be 3 cubic feet and didn't factor in the sub displacement, once you throw the subs in there it will change things, you'll have less volume at 2.64 cubic ft. and it will effect your tuning as well. Same for a sealed box, if you designed your box to be on the small end of things at 1.3 cubic ft. for the pair, adding the subs will now make your box .94 cubic ft.

My suggestion would be to build a 3 cubic ft ported box with a L port, tuned to 34-36Hz. If you plan on flush mounting your subs, a double baffle would be necessary, otherwise it would be a waste of time and money. I mean, it's not gonna hurt anything by doing it but for 2 12's on 1000 watts I just think it's overkill. And if you did go that route you'd have to make sure to accomodate for the extra baffle on your box plans cause it changes displacement a bit if you don't flush mount and adds some length to your port as well. Lastly, don't use anything other than 3/4" material, either MDF or Birch, whatever you can afford. Birch would be the better of the two but it's also a bit more expensive.

As for inverting your subs, the only difference that will make is less displacement inside the box. So if your subs displace .18 cubic ft. each, you'd have to build your box .36 larger than what you really want to end up with if you mounted them regularly. Inverting them would allow you to build the box to exactly the spec you want cause the subs are not taking up airspace inside of it. If your box is ported, you'd still have to account for port displacement though. Whatever you do, DON'T GUESS WHAT YOUR SUBS DISPLACEMENT IS and build your box according to your guess. Find out exactly what it is.
I love reading your posts man.. LOL Always good info
 
  #9  
Old 07-26-2011, 03:46 PM
Join Date: Oct 2010
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Are you being sarcastic? If not, I appreciate it.
 
  #10  
Old 07-26-2011, 07:24 PM
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Posts: 1,571
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Originally Posted by Milhouse View Post
Are you being sarcastic? If not, I appreciate it.
LOL im serious. Like I feel im a pretty knowledgeable guy in systems but I still learn stuff when you post your backup info to what you were claiming.
 

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