Power Port Design & Calculator - Home Theater Forum and Systems - HomeTheaterShack.com

Old 12-20-11, 12:53 PM Thread Starter
Senior Shackster
Mark

Join Date: Nov 2009
Location: East Midlands England UK
Posts: 129
Power Port Design & Calculator

I had been looking into these things for years but I never got very far until recently, when I stumbled accross a design for a power port that was designed to tune a 300L+ enclosure to 10Hz. Very soon after I found the calculator on another forum.

The idea behind these things is fairly straightforward. The picture you are about to see is effectively a cross section through the length of the port & you'll notice that the air exits at the sides rather than straight out of the end. This has the same radiating area as a much larger port but is a of a lot smaller, as far as I'm aware the port geometry also inhibits the ports natural resonance which can be a pain in a conventional reflex port. In other words it doesn't act like an organ pipe as a conventional port would due to it's length.

I'd love to have drawn my own picture, but credit must go to whoever actually did this one (apologies as I honestly cannot remember where I found this ). Kudos to whoever did though as I eventually came up trumps - thank you!

As you can see the port tube is quite a bit smaller in diameter than the original 8.72" port, so the air velocity inside is a lot higher. At each end it slows as it is expanding round the flow guides & at the exit of the port (on the sides) it has the same area as the original 8.72" standard port. Except now it's considerably shorter & much easier to fit into an enclosure

Here is what the spreadsheet calculation for that particular port looked like.

Effectively you need to work out a suitable conventional port with low enough air velocity so that the spreadsheet can calculate the power port from it's air mass. You'll want to have the equivalent mouth area of the standard port or greater to keep air velocity out of the port as low as your design requires.

You'll need Excel or Spreadsheet from Microsoft Works or similar to use the calculator.

pwrport.zip

Unzip & off you go...

E2A:- I really should add that this is a patented technology & while there should be no problem in using it for private use, it cannot be used commecially. Polk Audio own the patents.

Last edited by event horizon; 12-20-11 at 01:59 PM.
event horizon is offline

Old 12-27-11, 10:17 AM
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Steve Mechelke -mech

Join Date: Feb 2007
Location: Empire Township, MN
Posts: 14,914
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Re: Power Port Design & Calculator

Thanks for posting this here Mark!
mechman is offline
Old 12-27-11, 12:01 PM
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Mike

Join Date: Apr 2007
Posts: 19,397
Re: Power Port Design & Calculator

Mike P. is offline
Old 12-27-11, 02:50 PM Thread Starter
Senior Shackster
Mark

Join Date: Nov 2009
Location: East Midlands England UK
Posts: 129
Re: Power Port Design & Calculator

Quote:
mechman wrote: View Post
Thanks for posting this here Mark!
You are most welcome As I have learn't in the past it's best to spread things around, as if you lose them you have a much higher chance of getting them back again than if you didn't So while it is sure to benefit someone, or possibly a good few on here I may well be doing myself a favour down the line...

I know I found it incredibly handy, so I feel pretty sure others will...

Happy new year
event horizon is offline
Old 10-02-12, 06:30 PM
Senior Shackster
zac

Join Date: Mar 2007
Location: Roseville, CA
Posts: 125
My System
Re: Power Port Design & Calculator

Fantastic! Thanks for posting. Anyone know of someone who has molds or a setup to turn a few of these out?
zacjones is offline
Old 12-16-12, 11:05 AM
Senior Shackster

Join Date: Jun 2010
Posts: 207
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Re: Power Port Design & Calculator

the pictures in the original post are not showing. could you fix it please ?
zheka is offline
Old 12-17-12, 03:05 AM
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Bart

Join Date: Sep 2011
Location: Belgium, West Vlaander
Posts: 403
Re: Power Port Design & Calculator

Can't say this is what the thread starter meant, but it's the same name:
http://www.polkaudio.com/polk-univer...ogy/power-port
ßart West-VL. is offline
Old 12-17-12, 09:08 AM
Senior Shackster

Join Date: Jun 2010
Posts: 207
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Re: Power Port Design & Calculator

Quote:
ßart West-VL. wrote: View Post
Can't say this is what the thread starter meant, but it's the same name:
http://www.polkaudio.com/polk-univer...ogy/power-port
thank you. this must be it
zheka is offline
Old 02-17-13, 06:23 PM
Shackster
Steve

Join Date: Nov 2007
Posts: 92
Re: Power Port Design & Calculator

Thank you for this (I think) but how is the valve-like structure supported inside the port? Have you or anybody here actually built one please?
ALPHUX is offline
Old 09-20-13, 10:57 PM
Senior Shackster
John

Join Date: Jan 2011
Location: In the mitten, USA
Posts: 208
Re: Power Port Design & Calculator

Quote:
ALPHUX wrote: View Post
Thank you for this (I think) but how is the valve-like structure supported inside the port? Have you or anybody here actually built one please?
OK, so it's a bit late. LOL.
http://www.data-bass.com/data?page=system&id=8
Enjoy.
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