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Ports (Read 2342 times)
FlipC
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Posts: 14
Ports
09/17/07 at 10:13:31
 
So since I am in the process of building a HW
and am scaling it for 18" drivers to be used for PA work I have been thinking about the ports. The bottom is easy to understand. They are situated as to use the floor to extend frequency. But then we have the top port. First it is centered as all ports should be. But then it is out of phase with the bottom ports.
I wish I had some software to model
this and measure the differences between the direct radiated centered versus say centered frontal exit versus  in phase. Etc.

I do have the idea that the top port is
tuned higher to give a tighter sound but that is about it in my head.

For an install. The top port could be positioned
on a particular side in order to use a bounding wall just like the bottom 2 do the floor.


So it would be nice if the plans shared scaling along with
different port locations and their effects on the output for a given speaker.

Anyone want to share some input on the subject?


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asiquis
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Posts: 61
Re: Ports
Reply #1 - 09/17/07 at 14:53:35
 
I seems that building to exact specs works very well indeed. However, there is always the possibility of creativity in modifying the plan for your individual use.

I is often best to start with the original plan as designed by Steve and then if you wish try this and that.

I beleive from others forums in the past that the low frequency is from the upper port and higher frequency through the lower.

Ray
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FlipC
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Posts: 14
Re: Ports
Reply #2 - 09/17/07 at 18:17:28
 
Well high vs low frequency will depend on how a person loads
the cabinet. Which ever port is the frontal port will be the most efficient low freq port do to the direct radiation.  That with the actual tunning of each port.

I just suspect the reasoning behind the top firing
of the upper port is phase alignment. But sense I do not have any software to model this
and do not know an equation to figure it out. It is just theory.
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HT-EXT
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NYUK NYUK NYUK

Posts: 274
Re: Ports
Reply #3 - 09/20/07 at 20:47:35
 
Alot of the "BANDPASS" enclosures are one note wunders due to having the same ports in the same general area. To me the HWK uses two different ports for tuning purposes that way it is not just a one noter. I sure phase/alignment have something to do with it too but I am not smart enough to figure out how. Some of the more advance members should be able to explain all the details but getting them to let go of their secrets might be complicated. REPLIES WELCOME!


HT-EXT
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« Last Edit: 09/21/07 at 18:50:26 by HT-EXT »  

" I TRY TO THINK BUT NUT'EN HAPPENS! " CURLY
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aznboi3644
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I love YaBB 1G -
SP1!

Posts: 115
Re: Ports
Reply #4 - 09/21/07 at 01:03:01
 
the top port isn't "out of phase"

its just firing off axis
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