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Porting thru the Rear Deck

Discussion in 'Subwoofer Box and Custom Fabrication' started by Ranger SVO, Jul 29, 2008.

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  1. Ranger SVO

    Ranger SVO Full Member

    I was PMed the other day and was ask about a box in the trunk with the ports coming through the rear deck.

    I have a few questions also, so those of you who wanna do a little research, I need more info

    Normally when I do a box for SPL, I will build a box whose peak (Frequency where the relative gain is highest) closely matches the resonant frequency of the vehicle. This is not a problem if the box shares the same open space as the mic.

    But what if the box is in the truck. I think the rules would have to change. I don't think relative gain matters anymore. Or does it?

    So if we port through the back deck, I think we need to adjust the port tuning according to its distance from the mic. Also what if we have more than one port, Do we adjust each port differently. After all, their distance to the mic is different.

    I want input and links. Find me info
     
    Ranger SVO, Jul 29, 2008
    #1
  2. pedro quiroga

    pedro quiroga Well-Known Member

    you know what. try floridaspl.com. some of the guys there have rear deck ports.

    tommy the king of bass did one and it was pretty nice sounding. bass wise. not a big fan of the loud horn tweets.
    [​IMG]
    [​IMG]
    [​IMG]

    pay attention the rear glass. this thing had some deeep bass for what looked like 2 12's
     
    pedro quiroga, Jul 29, 2008
    #2
  3. aznboi3644

    aznboi3644 Full Member

    from what i've seen is that if you port through the rear deck the sub(s) should fire into the cabin and be sealed off from the trunk as much as possible
     
    aznboi3644, Jul 29, 2008
    #3
  4. jonnyv713

    jonnyv713 The Young Gun of CAT

    azn, i wanna put my 4 12's in the trunk and use part of it as an enclosure. i was going to put the ports through the rear deck. isnt that what u meant when u told me to do this?
     
    jonnyv713, Jul 29, 2008
    #4
  5. Ranger SVO

    Ranger SVO Full Member

    For 4 12-inch speakers we will need a minimum of 4 4-inch ports.

    But I have to say, this will not be an easy build. Think about it. You would have to build the box, or boxes. Put them in place. Then put in the ports. This will require holes in the rear deck and the boxes, all in the right place.

    The ports will need to be secured to both the back deck and the boxes. Not impossible by any means, but it would have to be well thought out.
     
    Ranger SVO, Jul 30, 2008
    #5
  6. jonnyv713

    jonnyv713 The Young Gun of CAT

    i am going to possibly fiberglass the rear deck and use it as part of the box. would that be a problem?
     
    jonnyv713, Jul 30, 2008
    #6
  7. Ranger SVO

    Ranger SVO Full Member

    I don't think any of this will be a problem, I personally have the ability to do this.

    I am just saying that this will not be a simple build. Every aspect of the build will have to be thought out in advance. This will be a challenging project.
     
    Ranger SVO, Jul 31, 2008
    #7
  8. electrolytic

    electrolytic Full Member

    Just a thought, maybe this will you give you a thought lol, the ports are usually designed to be level with the sub in theory so that the air inside the box can resonant-equalize with the air outside the box and being pushed by the subs. Right? So now if you have the ports outside the box the length of the ports wouldn't change but you will no longer have the resonating thing happening at the level of the subs. I don't know what to do about this or what really changes but something to ponder upon lol. Sorry i don't have time to research.
     
    electrolytic, Jul 31, 2008
    #8
  9. jonnyv713

    jonnyv713 The Young Gun of CAT

    well, ranger, i have always liked challenges and i think i am up to it. i took the measurements and it will be just over 10ft^2. i will give the exact measurements though. and i wanted to add something so maybe a little bit bigger.
     
    jonnyv713, Jul 31, 2008
    #9
  10. aznboi3644

    aznboi3644 Full Member

    Doesn't really matter where the ports are placed...placement depends on the install.

    I'll agree that this build will be difficult. I'd build two boxes and bolt them together in the trunk.

    In my experiences, subs firing in the trunk and ports into the cabin don't really give good results...I would just fire the ports into the trunk along with the subs.
     
    aznboi3644, Jul 31, 2008
    #10
  11. jonnyv713

    jonnyv713 The Young Gun of CAT

    whoa whoa whoa! u have just squashed all my plans azn... talk to me talk to me, please... and that is what i was planning on doing with the 2 boxes. well sorta...
     
    jonnyv713, Jul 31, 2008
    #11
  12. jonnyv713

    jonnyv713 The Young Gun of CAT

    here is a REAL quick design i did on paint. maybe someone can help me design it in 3D or improve it.
    untitled.jpg
     
    jonnyv713, Aug 1, 2008
    #12
  13. cccullen

    cccullen Full Member

    why don't you do what azn said. then all you could do so the bass would come into the cabin better is put some holes in the rear deck.
     
    cccullen, Aug 1, 2008
    #13
  14. aznboi3644

    aznboi3644 Full Member

    or could try a 4th order bandpass
     
    aznboi3644, Aug 1, 2008
    #14
  15. Ranger SVO

    Ranger SVO Full Member

    I think AZN is right. So I'm not gonna disagree with him. Two boxes is a good idea. Something else, bigger is always better. To a Point. Lets keep the 2 boxes between 4 and 5 cu ft. No bigger than 5.

    I also like the 4th order idea. But i'm not sure how to make it work with four woofers.
     
    Last edited: Aug 1, 2008
    Ranger SVO, Aug 1, 2008
    #15
  16. jonnyv713

    jonnyv713 The Young Gun of CAT

    well, im not TOTALLY sure what it is. and from what i know, it sounds like it will need more room. and i wont be ale to sow off the subs' looks
     
    jonnyv713, Aug 1, 2008
    #16
  17. jonnyv713

    jonnyv713 The Young Gun of CAT

    nvm i do know what it is, but will room be an issue?

    [​IMG]
     
    jonnyv713, Aug 1, 2008
    #17
  18. jonnyv713

    jonnyv713 The Young Gun of CAT

    some on guys! input input input!
     
    jonnyv713, Aug 3, 2008
    #18
  19. aznboi3644

    aznboi3644 Full Member

    what is that design you posted up?? If its a bandpass a single 4 inch port is nowhere near enough port area
     
    aznboi3644, Aug 4, 2008
    #19
  20. jonnyv713

    jonnyv713 The Young Gun of CAT

    that is just what i found on the net. i was jw if that is what we were talkin about and i found out it is. Azn, could u help me with a design? I know nearly nothing about these bandpass enclosures.
     
    jonnyv713, Aug 4, 2008
    #20
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