Multiplying vent length for half the sq.in needed
#1
Multiplying vent length for half the sq.in needed
Can you do that? Instead of 80sqin x 20" can you do 40sqin x 40" or does the port need to be large enough so that theres more air being pushed at one time? If the port is 40" x 1"-2" wide will that make for a weak port if it needs to be around 5-6?
#2
The length of the port in addition to the volume of the box will change the tuning frequency of the enclosure. Most subwoofers require around 12-16 square inches of port area per cubic foot of volume. So, want a box that is 1 cubic ft, the you would want a port that is 2" X 8" or 1" X 16". From there you will have to adjust the length of the port to adjust the tuning frequency. Here is a link to a box building calculator from RE that you can play around with to get a better idea.
Last edited by StickyFingaz; 05-24-2009 at 06:40 PM.
#3
I'd really like to know who came up with this port volume vs. box volume rule of thumb. It's moronic. No, sorry, that is insulting to morons.. Did some manufacturer put this in their manuals or on thier website or something???
To answer the question, NO you cannot make up for area by adding depth. As the area of a port gets smaller, so does the length, and vice-versa. It is not a total volume thing.
Also, a slot port should ideally not be more than to 6:1 in length vs. width and definitely never more than 12:1
To answer the question, NO you cannot make up for area by adding depth. As the area of a port gets smaller, so does the length, and vice-versa. It is not a total volume thing.
Also, a slot port should ideally not be more than to 6:1 in length vs. width and definitely never more than 12:1
#4
The numbers 2X8 and 1X16 were purely examples, thank you for clarifying.
#6
Show me these sites.
#7
I was being facetious when I said us morons. I just wanted to know why you thought it was a dumb rule of thumb. Here are a few links to manufactures sites that I was referring too. I think we can agree these are reputable companies all recommending 16 sqaure inches of port per cubic foot.
http://www.ddaudio.com/dd/caraudio/e...Size_hiEff.asp
https://ssl.perfora.net/www.ficaraudio.com/sess/utn;jsessionid=154a18920421b91/shopdata/0070_Tech/0070_Speakers/0020_Tech.BL/product_overview.shopscript
http://www.audioque.com/aq/portSize.htm
Obviously not all drivers have the same T/S and have different requirements, but at least it is a place to start, seeing how he hasn't posted any other information. To the original poster: what do you meant forward firing? Do you want the port on a different side of the box than the subs?
http://www.ddaudio.com/dd/caraudio/e...Size_hiEff.asp
https://ssl.perfora.net/www.ficaraudio.com/sess/utn;jsessionid=154a18920421b91/shopdata/0070_Tech/0070_Speakers/0020_Tech.BL/product_overview.shopscript
http://www.audioque.com/aq/portSize.htm
Obviously not all drivers have the same T/S and have different requirements, but at least it is a place to start, seeing how he hasn't posted any other information. To the original poster: what do you meant forward firing? Do you want the port on a different side of the box than the subs?
Last edited by StickyFingaz; 05-26-2009 at 06:01 PM.
#9
I was being facetious when I said us morons. I just wanted to know why you thought it was a dumb rule of thumb. Here are a few links to manufactures sites that I was referring too. I think we can agree these are reputable companies all recommending 16 sqaure inches of port per cubic foot.
DDAudio Digital Designs Speakers Made in the USA
https://ssl.perfora.net/www.ficaraudio.com/sess/utn;jsessionid=154a18920421b91/shopdata/0070_Tech/0070_Speakers/0020_Tech.BL/product_overview.shopscript
AudioQue
Obviously not all drivers have the same T/S and have different requirements, but at least it is a place to start, seeing how he hasn't posted any other information. To the original poster: what do you meant forward firing? Do you want the port on a different side of the box than the subs?
DDAudio Digital Designs Speakers Made in the USA
https://ssl.perfora.net/www.ficaraudio.com/sess/utn;jsessionid=154a18920421b91/shopdata/0070_Tech/0070_Speakers/0020_Tech.BL/product_overview.shopscript
AudioQue
Obviously not all drivers have the same T/S and have different requirements, but at least it is a place to start, seeing how he hasn't posted any other information. To the original poster: what do you meant forward firing? Do you want the port on a different side of the box than the subs?
Further to that, DD is after a certain performance from their drivers and their box chart there allows Joe Consumer to build something that works with a DD speaker. Move to a different brand of speaker though and it's a guess on how well it will work.
Proper speakerbox design should consider the driver you are using and what you want it to do. People would laugh openly if one said that every 10" driver should go into a 0.75cuft box. At the same time, it is laughable to believe every 0.75cuft box should have a 12sqin vent in it.
Anyway - again thanks for the links. I knew someone had to have posted that bad info somewhere.
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