Printer Friendly Forum Posts - Port size and length

I have a fifteen and the recommended port length is 11in. but I can only use about a 7in port length, with 4in of space from the bottom of the box. I was wondering how this will effect the sound and if there is something I can do so it doesn't effect the sound.

if you can't get the port long enough, then make a vent and do an L shape (if your building the box yourself, it'd be hard to put a vent port on a box that's already built...)

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Bad Boys Customs
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If you use it. Suport it. Donate to the 12 volt!

Everything is already built. I'm putting it in a friends car. Sou you wouldn't suggest me to use it unless I can use the proper size port?

if you cant use the proper size it is going to change the tuning frequency, if it is meant to be 7x15 and you only do 4x7 say therotically the port was tuned to 36hz origanally it could raise the tuning frequency to 45-50hz. you would lose alot of low bas and also risk damaging the subs if you dont use a sub sonic filter

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2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
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yea the proper port it really essential, if you can't fit it in there curve it, use pvc for the port and just get an elbow peice

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Bad Boys Customs
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If you use it. Suport it. Donate to the 12 volt!

The port is supposed to be (2) 4x11 and the ports are (2) 4x7. so if I would put an elbow on the bottom of the port that is a total of about 4in. than that would help. It doesn't seem like it would be that of a dramatic difference.

it may not seem like a few inches makes that big of a difference but it really does, but if you think about it 4 inches out of 11 is like 39% so that's a big difference in the size of the port, half an inch might not matter much but almost 40 % difference will for sure

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Bad Boys Customs
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If you use it. Suport it. Donate to the 12 volt!

It is the ports that are supposed to reduce the noise. I can't think of what they are called but he put them in without even measuring or looking at the suggested length. So if I just pop off the bottom and bend a peice of pvc to a right angle that is around 4in longer than would that be fine I'll try to draw a little pic to show you what I mean. Thanks for all the help you;ll can provide

i'm not sure what your talking about, most people that i've seen just use like a 2 or 4 or whatever inch pvc peice to do the port, and then an elbow would pop right on that with NO problem,, take or draw a pic cause i'm not sure what you mean

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Bad Boys Customs
audio - video - security

If you use it. Suport it. Donate to the 12 volt!

https://tinypic.com/view.html?pic=4qomrl There is a pretty crappy drawing. There is one port in front of the other. If I just put that bend on both of the ports it should make it back to spec right. Please correct me if I'm miss understanding your advice.

is there already a bend in it? or did you draw what it would be like if you added the bend? i don't really get what kind of a port that is,, is the current port just a peice of tube or what? i'm kinda lost on what your current box situation is

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Bad Boys Customs
audio - video - security

If you use it. Suport it. Donate to the 12 volt!

here are the ports that are in the box https://www.crutchfield.com/S-eZNCf84ao9x/cgi-bin/ProdView.asp?g=745&I=495PNR4 they are currently 4in from the bottom of the box. I figure i could get an elbow or maybe even put a whole new port in the box, which I would hate to do because the ports seems pretty nice. The drawing was what I thought it would look like if I had put the elbow on the end of it. So would it be better if I just put a new port in or try and put an elbow in?

yea i don't know how much the flair really helps,, but anyways, i don't think you'll beable to put an elbow on that tube, just won't fit over that flair stuff, you might have to just get some pvc

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Bad Boys Customs
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If you use it. Suport it. Donate to the 12 volt!

You can remove the end flares, but either way I will probably just get some pvc. I wonder if the elbow subtracts the length because of the bend. Thanks for all the help Catanham I just never really dealt with ported boxes. I look forward to hearing from you about the HU.

keep the end flares on them...it helps to reduce port noise. here is a good example of port noise..you know when you have a bottle of pop, and when your bored sometimes, you blow over top the hole and it makes a noise.....well same thing applies to a port. making a square port would be better and flanging it...but making it slotted and flanged or flared for you techy's, would be your best bet.

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xTimx

I don't know if I will be able to fit the flares on a peice of 4in pvc. I'm using round (2)4in pvc and it's going to have to be 7in long and then a 90degree bend with about 4 more in. No one has still really gave me a direct answer, if I use a 90degree bend will I need to compensate for the length lost in the bend or not. The only thing that I have seen was a write-up on JLs web site. Do you think I will have excessive port noise if I just use round pipe and slightly round/file the inner edge down so it's not a direct drop?

when measuring the port with a 90* bend! you throw an imaginary line thrue the center of the port including the bend or circumferance of that ben and that will give you your total lengh of the port. i would only worry about the port noise if you are trying to use a too small of a port diameter for a huge sub, yes by slightly rounding the ports inner edges down you will help minimize the port hizzing noise if any.

if you input your enclosure and speaker dimension in to winisd software " free google searsh" it will tell you if the port diameter and length you have right now are proper. and to what freq are they tuning this box to.