# Changing port length



## Stryker27 (Jul 10, 2009)

Hi all,
this is my first post here and i've read alot of good threads in here so hopefully i can get a good answer to my dilemma/question i have. 
I have a 4.2 cu/FT box separate chambers with 2.1 per side. ports are 4"wide and 8"long.
I believe it's tuned for around 37.5Hz. I would like to tune it lower to say between 32-34. I realize i only need to replace the port with longer one. Should I use a PVC elbow of 90 degrees inside or just have some sticking out the box and not flush, or both depending on how long the new one would be? there is nothing wrong with the way it sounds/hits as it sits just wondering if it will make a noticeable difference. everyone seems to say go low if you can. does an elbow hurt flow of air(restrict it)?
My setup is 2-15"Clarion Pro audio 1542 dual 2 OHM VC one PG Rsd 1200.1 per sub and a bass cube.
It's not too much of a hassle to switch I just do not want to lose some impact cause I'm tuning it lower. Once I swap it out I may have to live with the switch. I posted a pic of the box and I may only be able to slap an elbow on on the inside extending it out may be too close to the seat back.
thx


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## Oliver (Jun 25, 2007)

I'd leave it the way it is, [ but then i have had some built after i designed them ]


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## Viperoni (Oct 14, 2006)

If the port would get closer than 4" from the back of the box, use a 45 degree elbow or even two of them, that'll air in the port from experiencing too much restriction.


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## cubdenno (Nov 10, 2007)

I haven't modeled your woofer/enclosure combo but tuning lower is not necessarily going to give you "more". Most music (and by most, 95% or so) does not go below 30 hertz. Your post is in the SPL section so I am assuming that you are looking for output. I would leave your ports alone. For SQL applications I have become a big fan of the 40-45 hertz range in cars, especially hatchbacks. TF gets you down to the upper 20's audibly and the nice exaggerated hump at the tuning frequency really pounds out the bass. Plus you can in conjunction with a subsonic filter, use a bass boost in the 40-45 hertz area(wisely please as in don't crank it.) for some extra impact.


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## grindkt88 (Jun 14, 2006)

I agree a parimetric EQ would probly give you what ur looking for.


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## Stryker27 (Jul 10, 2009)

grindkt88 said:


> I agree a parimetric EQ would probly give you what ur looking for.


I'm just gonna leave it as it is. 
I have a PG bass cube, that is a one band para EQ in it's self with 0-18 Db of boost at my tuned freq of 39 Hz, plus 2 PG-215ix eq's. I guess I should be happy with what i have for now.... Probably will never be happy unless the subs leave me with internal bruising:laugh:


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## cubdenno (Nov 10, 2007)

My guess is that you would get more output by using a larger box. 2 cubic feet for a 15"... Choking them.


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## BassAddictJ (Oct 1, 2009)

i love the tuning point of lower 30hz's personally. you'll likely loose a slight bit of dB on your peak notes, but it'll go lower and probably sound more musical. Most rap that uses low notes dont go lower than 30hz. Tuning around 33-35hz is a good spot IMO. 

Increasing the volume tends to make the woofers require less power to reach full excursion. You might be better off making a new box if you're not planning on upping the power.


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