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  1. #1
    riddla's Avatar
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    port noise

    Ive built a ported sub box for my vibe 12in subs of my head.
    When i crank it up it sounds nice & deep but when i crank it up real loud & put my head nr da ports, im getting port noise.

    my port is 4in & i have it going very deep into the box but not touching da bottom obviously.
    Also, its quite close to the wall of the box.

    Can u guys gi mi some help as to why u think im getting this please, thanks.

    By da way, i is from rainy old England, ruff London sides..

    Thanks again







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    Re: port noise

    Quote Originally Posted by riddla
    Ive built a ported sub box for my vibe 12in subs of my head.
    When i crank it up it sounds nice & deep but when i crank it up real loud & put my head nr da ports, im getting port noise.

    my port is 4in & i have it going very deep into the box but not touching da bottom obviously.
    Also, its quite close to the wall of the box.

    Can u guys gi mi some help as to why u think im getting this please, thanks.

    By da way, i is from rainy old England, ruff London sides..

    Thanks again
    lemme guess... pre fab box?

    Well, 4" circular ports aren't all that large to begin with. It might be alright for about 200~300w RMS, but with higher power and performance subs, 4" is a laugh. Have a look at how large a port some of the guys here use. We're talking slot ports here (rectangular, larger opening).

    If you want to rectify the prob, try to make yourself a new box, with a larger port opening. (The port sizeand length will have dramatic diff in performance of your sub.)

    BTW< Ali G in da house!~ I like my punabi :P



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    Re: port noise

    Thanks for da reply m8, i havent sealed around the port holes as yet but the noise doesnt seem to come from around that area, it comes from inside the actual port itself so i think..




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    Re: port noise

    Quote Originally Posted by riddla
    Thanks for da reply m8, i havent sealed around the port holes as yet but the noise doesnt seem to come from around that area, it comes from inside the actual port itself so i think..
    erm, m8, I wasn't talkig abou sealing around the port. I'm saying the port is too small for the output of the subs. You need a new box with a larger port.

    The sound you hear is what people refer to as air or port turbulence. Too much air trying to get through such a small opening.



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    Re: port noise

    Also make sure that the port opening on the inside of the box is as far from the back of the box as it is wide. If you have a 4" port it should be 4" away from the back of the box.



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    Re: port noise

    Quote Originally Posted by Trixter
    Also make sure that the port opening on the inside of the box is as far from the back of the box as it is wide. If you have a 4" port it should be 4" away from the back of the box.
    Thanx for all da info guys, i know know where i went wrong, im going to have to build another one as my box is to small now to make any changes..

    What about a 5in port compared to a 4in, would it expel the air better?

    Would the sound be deeper as my 4in port seems to be struggling with the air being pushed through it?




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    Re: port noise

    Quote Originally Posted by riddla
    What about a 5in port compared to a 4in, would it expel the air better?
    Yes, but at the same time it would have to be longer than the 4" port, so consider that when building.

    Would the sound be deeper as my 4in port seems to be struggling with the air being pushed through it?
    Not necessarly deeper but parhaps "smoother" sounding due to the air not being as constricted. If your looking at using a round port, look at the Presicion Port. It can be found at http://www.partsexpress.com/pe/showd...D=117898&DID=7. The have flared ends to minimize port distortion. I have used them before and I like them.



    2006 Jeep Liberty
    Adire Audio, Cadence, Clarion, MB Quart

    Lv = [(14630000 x R^2) / (Fb^2 x Vb)] - 1.463R
    *Vb = vol. in cu"
    **R = sq.rt. A / Pi (for square/slot port)

  8. #8
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    Re: port noise

    Quote Originally Posted by Trixter
    Yes, but at the same time it would have to be longer than the 4" port, so consider that when building.

    My port at the moment is near to the bottom of the box already so if using a 5in port, would i have to make the box a little bit deeper or could i use the same measurements & lengthen the port length slightly, if i do this, it would be very nr to the bottom of the box but not touching.

    Would this also affect sound quality if its to close to the bottom?



    Not necessarly deeper but parhaps "smoother" sounding due to the air not being as constricted. If your looking at using a round port, look at the Presicion Port. It can be found at http://www.partsexpress.com/pe/showd...D=117898&DID=7. The have flared ends to minimize port distortion. I have used them before and I like them.
    I will be using a round port as i dont really understand much about slot ports.

    Cheers mates




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    Re: port noise

    regarding my original box, what if i was to build another port directly on the box, would this give me better sound.
    The box is dbl but sealed chambers & the ports are at the botton so could i put 2 ports on the top as well???




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    Re: port noise

    Quote Originally Posted by riddla
    regarding my original box, what if i was to build another port directly on the box, would this give me better sound.
    Not quite sure what you mean. Please explain.

    [qoute]The box is dbl but sealed chambers & the ports are at the botton so could i put 2 ports on the top as well???[/QUOTE]

    If you add more ports then you need to make all the ports longer to make up for adding more. Which will also add more displacement in turn making the box smaller. These are the things that need to be thought of before building the box.



    2006 Jeep Liberty
    Adire Audio, Cadence, Clarion, MB Quart

    Lv = [(14630000 x R^2) / (Fb^2 x Vb)] - 1.463R
    *Vb = vol. in cu"
    **R = sq.rt. A / Pi (for square/slot port)

  11. #11
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    Re: port noise

    alright guys, im really baffled here,
    Basically i gave some wrong info before, my old port was 2.5in wide & is shite, what i want to use now is 4in but now need to make my box bigger, my sub reccommends 1.5cft but i wanna go a little bigger say 2cft is that ok to start with?

    also my dimensions for my box are 13in high x 32in wide x 12.5in deep.
    Now when placing my port in the box, it obviously isnt gonner be able to go that deep, only about 10in deep from these measurements befor it starts touching the wall, its a round pvc plastic pipe?

    I want low bass so would i have to bend it to make it longer cause 10in deep dont seem long at all?
    how do i bend it, sorry for the stupid questions but can u guys please help me out?
    and tell me if these box dimensions are ok???




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