# Port or Vent placement HT



## Foglght (Aug 2, 2007)

I have been reading thread after thread over at ICIX about what to do with the 2 EHQS 12" subs I have laying around. Some of the box designs have the port at a 90 deg. angle, and some are running parallel. I've seen a bunch use the 4" aero port, while others use just a square vent. Is there any place I can get some difinitive information on what each one is good for, as far as type of port, length, and placement?

I don't know the formulas to calculate port tuning. 

Thanks in advance.


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## Ga foo 88 (Dec 18, 2005)

Do you know the general port area used for HT use, most are probably ebs enclosures? Aero ports will really only benefit you if you have insufficient port area and the small port is making a noise.


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## Robert_J (Nov 9, 2006)

There is no difinitive rule for port placement. If there was a "best spot" on the enclosure, then most retail manufacturers would use that spot. Right now, port placement is all over the map.

Port shape is a controversial one. A cylinder has the most port area with the least amount of surface area. There is less air friction. It is also very easy to cut a circle and stick in a plastic port. Flared ports help when the port area is smaller than recommended. It keeps the chuffing to a minimum. A slot port can add additional bracing inside a sub which is never bad.

As for port size, I use the suggestions generated from Unibox. WinISD will work as well. If you want to do the calculations by hand, diysubwoofers.org has the formulas.

-Robert


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## Foglght (Aug 2, 2007)

Well one of the build options had a 4" Aero port which I believe was around 15" long. It was supposed to be tuned for around 23hz. I wanted to use both of the drivers as they are 2ohm subs, so the new design has a 3" by 18" slot port and is around 9 cubic feet. I was just trying to figure out if the slot port or the round port would have any benefits or drawbacks.


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## niceguy (Mar 12, 2006)

I agree w/the posts above...another factor is enclosure size vs port length if you're trying to use round (PVC) ports...sometimes depending on the box and port length, you may be better off using a slot. However, that may rarely be necessary in HT where you generally have large cf enclosures...

Jeremy


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## Spasticteapot (Mar 5, 2007)

I'm reasonably sure that a larger port diameter will reduce chuffing, and I know for sure that a flared port, flush mounted to the box, will help quite a bit.

As long as you're not putting it in the back of a moving vehicle, you may as well go wild with the bracing. I'm lining my next speakers with concrete.


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## Foglght (Aug 2, 2007)

niceguy said:


> I agree w/the posts above...another factor is enclosure size vs port length if you're trying to use round (PVC) ports...sometimes depending on the box and port length, you may be better off using a slot. However, that may rarely be necessary in HT where you generally have large cf enclosures...
> 
> Jeremy


I'm looking at about 8.5 ft^3 tuned to 20 hz.


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## Oliver (Jun 25, 2007)

I thought this was done very tastefully !









View from bottom & backside


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## Foglght (Aug 2, 2007)

Yes, yes it was. I do not currently possess those skills.


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## chad (Jun 30, 2005)

a$$hole said:


> I thought this was done very tastefully !
> 
> 
> 
> ...


That's his turntable stand


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## Robert_J (Nov 9, 2006)

Foglght said:


> I do not currently possess those skills.


 If you can't cut wood, then you shouldn't be building a sub. That's just an MDF box with hardwood glued on the outside. Difficult - no. Time consuming - very. You do have to be accurate with your cuts. A tablesaw and sander are required.

-Robert


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## Oliver (Jun 25, 2007)

Try knitting , nieces and nephews find items that are knitted to be ... well knitted


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## Foglght (Aug 2, 2007)

Robert_J said:


> If you can't cut wood, then you shouldn't be building a sub. That's just an MDF box with hardwood glued on the outside. Difficult - no. Time consuming - very. You do have to be accurate with your cuts. A tablesaw and sander are required.
> 
> -Robert


I can cut wood.....and a rug, just fine. Putting together a really nice piece such as that, probably out of my range of abilities for now.

After looking at other boxes that A$$hole has shown us, I would have doubted that it was just a MDF box with stuff glued on the outside. 

So I suppose in the spirit of DIYMA, I should never attempt to make a box due to the sad fact I can't make a masterpiece box.


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