1. ## Trying to understand a particular box design

Guys, I need some help with a box design I am looking at. See the attachment below because I made a drawing of what I am going for. When you see the picture, please assume that the port height is the same as the internal height of the enclosure. Here are my questions:

1) Would this design be considered as having two ports? If the enclosure has two ports then I assume I would be correct by doing the port length formula for two ports?

2) Would the woofers see both chambers for airspace since I am not putting in a divider?

3) If the width of the mouth opening is say 3 inches, do I stay off of the back wall 3 inches with both bends or do I stay from the backwall 1.5 inches?
Last edited by Goldtaz1; 01-10-2006 at 10:58 AM.

2. ## Re: Trying to understand a particular box design

put a divider down the middle and make it wider so that the middle section is double the *internal* width of the bottom 'shafts' i suppose. each sub would be in its own seperate box. but you can NOT do a port like that where they both have two tails that share the same middle shaft.

________
|___|||___|

see the divider? then put the back two beside them or whatever. but you cant share the same middle one off to the others

3. ## Re: Trying to understand a particular box design

i would disagree with req.
you can do it the way you said. if you wanted the mouth to be 3" then you would figre the port for 1/2 the box. using 1.5" port. pretend that its 2 seperate boxes w/ 2 1.5" ports 'joined' together. i just did a box like this not to long ago

(internal pics)

(finished pics)

4. ## Re: Trying to understand a particular box design

Thanks a bunch jellyfish, that definitely sheds light on my project. However, I just want to make sure I understand you correctly, here goes. If I am looking for 2 cubes PER woofer and say 42 square inches of port where the mouth is 3 inches wide and a tuning of let's say 33 Hz then in order to find port length I would perform my calculation using 1) 2 cubes net 2) 21 square inches of port and 3) the 33 Hz tuning frequency??? If this is correct then I knew I was making it more difficult then it really is?

Also, on your second link the pictures would not pull up, so would you mind sending those via PM or to [email protected]?

5. ## Re: Trying to understand a particular box design

Originally Posted by Goldtaz1
Also, on your second link the pictures would not pull up, so would you mind sending those via PM or to [email protected]?
they worked for me.

6. ## Re: Trying to understand a particular box design

Originally Posted by Insomniac119
they worked for me.

Still can't get em to work.

7. ## Re: Trying to understand a particular box design

worked for me at 6.03 on april 7th.

8. ## Re: Trying to understand a particular box design

Originally Posted by Goldtaz1
Thanks a bunch jellyfish, that definitely sheds light on my project. However, I just want to make sure I understand you correctly, here goes. If I am looking for 2 cubes PER woofer and say 42 square inches of port where the mouth is 3 inches wide and a tuning of let's say 33 Hz then in order to find port length I would perform my calculation using 1) 2 cubes net 2) 21 square inches of port and 3) the 33 Hz tuning frequency??? If this is correct then I knew I was making it more difficult then it really is?

Also, on your second link the pictures would not pull up, so would you mind sending those via PM or to [email protected]?
yes you are correct sir.
the pics don't work? huh, but the first ones do? they're both on the same server...
i'll see if i can find them.

for instance if you calculation comes to 30" long port and your box is 17" deep, you would take 3" down the middle, then you split it, and have 1.5" running each way 12.25"...make sence?

9. ## Re: Trying to understand a particular box design

Originally Posted by Jmac
Can anyone say, "Cancellation" ???
you were the one that helped me figure mine out when i did it, and there was no mention of cancelation...

10. ## Re: Trying to understand a particular box design

Originally Posted by Jmac
Can anyone say, "Cancellation" ???

This box design is still about as clear as mud to me. Jmac please clarify this issue, I don't think that either Jellyfish nor myself wants to build a completely worthless box?? Additionally, we don't want to go around advising other folks incorrectly, so please help us out on this one.

Jellyfish, I am quite positive that we are on the same sheet of music and I just wanted to let you know I appreciate your help.

11. ## Re: Trying to understand a particular box design

Need some response on this.

12. ## Re: Trying to understand a particular box design

Originally Posted by Goldtaz1
Need some response on this.

i have already built my box. it sounded great! louder than the 'regular' ported that i just built for the 2-10's

13. ## Re: Trying to understand a particular box design

Originally Posted by jellyfish420

i have already built my box. it sounded great! louder than the 'regular' ported that i just built for the 2-10's

Do you know Jmac? Do you suppose we could go to him directly for some assistance? Anyone else familiar with this design please feel free to chime in.

14. ## Re: Trying to understand a particular box design

yea. i thought there could be some cancellation issues, but was never vertain. so fo the boxes i design i give them two seperate ports just incase. (like the one in my sig).

15. ## Re: Trying to understand a particular box design

Originally Posted by Jmac

Anyone see a problem here ?

The waves will be completely out-of-phase when the meet up in the center of the port and cancellation will occur ...

You should have a divider in the middle of the port ...
But I have seen many boxes built this way and they absolutely slammed. I am talking about boxes that were built by the professionals at my local car audio shop. One guy in particular has won numerous national awards for his builds. If you require his name then I can certainly provide that.

I guess the main reason I am questioning you on this is because Jellyfish stated that you helped him design his enclosure.

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