Easy Slot Port Design Questions - Page 2 - Home Theater Forum and Systems - HomeTheaterShack.com

Old 12-29-09, 11:17 AM Thread Starter
Shackster
strongman

Join Date: Dec 2009
Location: New Jersey
Posts: 18
Re: Easy Slot Port Design Questions

Thanks Kevin.

Using the simple calculator David provided, for a 5.1 cu ft. enclosure tuned to 21 Hz, a 1.5" x 18.5" port should be about 29 inches long. Does that seem appropriate to you for this box? Also, how much polyfill would you recommend?

Thanks, David
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Old 12-29-09, 11:31 AM
Kevin

Join Date: Nov 2007
Location: Port Angeles, WA
Posts: 1,026
Re: Easy Slot Port Design Questions

Quote:
strongman wrote: View Post
Thanks Kevin.

Using the simple calculator David provided, for a 5.1 cu ft. enclosure tuned to 21 Hz, a 1.5" x 18.5" port should be about 29 inches long. Does that seem appropriate to you for this box? Also, how much polyfill would you recommend?

Thanks, David
I get 28" for that tune with an empty box which is close enough. That is 27.75 in^2 port area, add 80% fill and it drops to about 24" in length. Account for all the braces, the driver and the amp too and make sure you get at least 5.1 cubic feet. A little extra won't hurt and account for the bend in the end of the port. It is longer than the length of the shelf because it bends near the inside termination.

Exodus Audio
Old 12-29-09, 12:00 PM Thread Starter
Shackster
strongman

Join Date: Dec 2009
Location: New Jersey
Posts: 18
Re: Easy Slot Port Design Questions

Perfect.

One more dumb question. How do I figure how much polyfil is needed to provide "80% fill".

Thanks so much for the help.
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Old 12-29-09, 12:06 PM
Kevin

Join Date: Nov 2007
Location: Port Angeles, WA
Posts: 1,026
Re: Easy Slot Port Design Questions

Quote:
strongman wrote: View Post
Perfect.

One more dumb question. How do I figure how much polyfil is needed to provide "80% fill".

Thanks so much for the help.
16oz per cubic foot = 100% fill.

So...about 65oz. You can buy 20oz. bags at Walmart so three bags should be close enough.

Exodus Audio
Old 12-29-09, 12:14 PM Thread Starter
Shackster
strongman

Join Date: Dec 2009
Location: New Jersey
Posts: 18
Re: Easy Slot Port Design Questions

Thanks.

I'll press on the get the enclosure ready, and I'll be looking forward to the arrival of the driver and amp!

David
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