Vented box question - changing the number of ports

dooper · 23rd January 2012, 11:42 PM

I have enclosure plans that call for four ports, 2.38" ID x 3.5" long. I was playing around with the AJ Vented Designer application and came up with these alternatives using two ports instead of four:

1) 2.38" ID x 0.88" long

2) 2.75" ID x 1.49" long

3) 3.00" ID x 1.97" long

4) 4.00" ID x 4.48" long

Does the math look right here? If yes, is there a preferred choice?

Thanks,

dooper

weltersys · 24th January 2012, 12:16 AM

Bigger and longer is better for speakers with big displacement.

The disadvantage of large ports is the port area needs to be deducted from cabinet volume, so you end up with a larger box.

The port size estimates look reasonable.

revboden · 24th January 2012, 12:31 AM

What is the box volume?

dooper · 24th January 2012, 01:00 AM

Quote:

Originally Posted by revboden

What is the box volume?

The gross internal volume is 5610 cubic inches -- 34 x 15 x 11.

revboden · 24th January 2012, 08:46 PM

1. 50.2Hz
2. 50.6Hz
3. 50.8Hz
4. 51.7Hz

Have you tried 'Boxnotes' and 'Flare-it'? Very handy for figuring out port velocity requirements.

dooper · 24th January 2012, 08:47 PM

Thanks -- I'll check that out!

revboden · 24th January 2012, 09:24 PM

Design at Subwoofer-Builder.com

23rd January 2012, 11:42 PM	#1
dooper diyAudio Member Join Date: Jan 2004 Location: Canada	Vented box question - changing the number of ports I have enclosure plans that call for four ports, 2.38" ID x 3.5" long. I was playing around with the AJ Vented Designer application and came up with these alternatives using two ports instead of four: 1) 2.38" ID x 0.88" long 2) 2.75" ID x 1.49" long 3) 3.00" ID x 1.97" long 4) 4.00" ID x 4.48" long Does the math look right here? If yes, is there a preferred choice? Thanks, dooper

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24th January 2012, 12:16 AM	#2
weltersys diyAudio Member Join Date: Jan 2008	Bigger and longer is better for speakers with big displacement. The disadvantage of large ports is the port area needs to be deducted from cabinet volume, so you end up with a larger box. The port size estimates look reasonable.

24th January 2012, 12:31 AM	#3
revboden diyAudio Member Join Date: Feb 2011	What is the box volume?

24th January 2012, 08:46 PM	#5
revboden diyAudio Member Join Date: Feb 2011	1. 50.2Hz 2. 50.6Hz 3. 50.8Hz 4. 51.7Hz Have you tried 'Boxnotes' and 'Flare-it'? Very handy for figuring out port velocity requirements.

24th January 2012, 08:47 PM	#6
dooper diyAudio Member Join Date: Jan 2004 Location: Canada	Thanks -- I'll check that out!

24th January 2012, 09:24 PM	#7
revboden diyAudio Member Join Date: Feb 2011	Design at Subwoofer-Builder.com

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