Port question, round vs rectangular

kvk · 7th February 2008, 06:13 PM

I promise I'm almost done with my noob questions.

If a port is spec in a raound, dia x len, is there a conversion to rectangular?

Intuitively, I'd guess to keep area and length the same but my guess is that you might need also change area a tad, maybe like up it a few %.

I found this cool calculater but it only does round ports, not slot--
http://www.mhsoft.nl/Helmholtzabsorber.asp

vinylkid58 · 7th February 2008, 08:17 PM

Quote:

Originally posted by kvk
If a port is spec in a raound, dia x len, is there a conversion to rectangular?

Intuitively, I'd guess to keep area and length the same but my guess is that you might need also change area a tad, maybe like up it a few %.

You're on the right track, so to speak. Just compare area to area, all you need to know is the diameter of the port to calculate it's area. Just keep the length the same for either.

Jeff

kvk · 8th February 2008, 01:08 AM

Alright, let's muddy the water.

Keep the area the same put flares on the ends of the port. Do you measure the length the beginnings or ends of the flares or somewhere in between?

My guess would be about 1/2 in between the beginning and end of the flares but that's just intuition. I'm the noob here.

vinylkid58 · 8th February 2008, 02:30 AM

Quote:

Originally posted by kvk
My guess would be about 1/2 in between the beginning and end of the flares but that's just intuition. I'm the noob here.

I can't give you a definitive answer, but there is an "end correction" function which deals with this issue when modeling boxes. Obviously, the correction factor will grow as the port gets larger, but I don't know how to calculate an exact number.

What you suggest makes sense, as long as you are dealing with only one (1) vent.

Jeff

soongsc · 8th February 2008, 03:22 AM

http://www.subwoofer-builder.com/flare-testing.htm

cabbagerat · 8th February 2008, 07:19 AM

Try WinISD Pro. It supports simulation of both round and rectangular ports. The help file also has a lot of interesting info about ports, end correction, and other topics.

Commsandsound · 11th February 2008, 08:16 AM

Hi
Dont forget to check the port length unless it is just a hole.

regards

www.commsandsound.com

7th February 2008, 06:13 PM	#1
kvk diyAudio Member Join Date: Jan 2008	Port question, round vs rectangular I promise I'm almost done with my noob questions. If a port is spec in a raound, dia x len, is there a conversion to rectangular? Intuitively, I'd guess to keep area and length the same but my guess is that you might need also change area a tad, maybe like up it a few %. I found this cool calculater but it only does round ports, not slot-- http://www.mhsoft.nl/Helmholtzabsorber.asp

8th February 2008, 03:22 AM	#5
soongsc diyAudio Member Join Date: Mar 2005 Location: Taiwan	http://www.subwoofer-builder.com/flare-testing.htm __________________ Hear the real thing!

11th February 2008, 08:16 AM	#7
Commsandsound diyAudio Member Join Date: Feb 2008	Port length Hi Dont forget to check the port length unless it is just a hole. regards www.commsandsound.com

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8th February 2008, 01:08 AM	#3
kvk diyAudio Member Join Date: Jan 2008	Alright, let's muddy the water. Keep the area the same put flares on the ends of the port. Do you measure the length the beginnings or ends of the flares or somewhere in between? My guess would be about 1/2 in between the beginning and end of the flares but that's just intuition. I'm the noob here.

8th February 2008, 07:19 AM	#6
cabbagerat diyAudio Member Join Date: Jan 2004 Location: Cape Town	Try WinISD Pro. It supports simulation of both round and rectangular ports. The help file also has a lot of interesting info about ports, end correction, and other topics.

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