Tuning a port full of straws?

bigerik · 22nd January 2005, 03:40 PM

Hi All
My Seas project is built in an old ProAc Response 2 Cabinet. It is a ported cabinet, but the port is full of straws, as ProAc likes to do. Now, testing showed that the port was tuned to 50Hz, while this driver would be happier with it tuned to 45Hz. Of course, I could just remove the straws and try it the normal way, but as I have never tried a port with straws in it, it would be fun to give it a try.
Anyone have any suggestions? the port is 3 inches wide, and the straws are about 6 inches or so long.
Any help/suggestions would be appreciated!
Thanks
Erik

Bill Fitzpatrick · 22nd January 2005, 04:38 PM

"A Port Full of Straws", what a wonderful name for a rock band.

bigerik · 22nd January 2005, 05:10 PM

LOL
Does have a nice ring to it....

E

GM · 22nd January 2005, 05:41 PM

The straws makes it somewhat aperiodic, so removing them will raise Fb and increase any peaking a bit, ergo either use a smaller vent or straws or longer vent or straws or some combination of these.

GM

bigerik · 22nd January 2005, 06:04 PM

Quote:

Originally posted by GM
The straws makes it somewhat aperiodic, so removing them will raise Fb and increase any peaking a bit, ergo either use a smaller vent or straws or longer vent or straws or some combination of these.

GM

Not wanting to look stupid but....
huh?

Erik

GM · 22nd January 2005, 07:27 PM

Aperiodic means 'without ringing', i.e. there's no peaking at Fb WRT speaker damping, or sometimes referred to as critically damped, though most folks don't like it this well damped since it rolls off the bass too much for their tastes. Anyway, the straws add a certain amount of acoustic resistance like stuffing does, so longer straws or a higher quantity of smaller straws will lower Fb. Or you can make a smaller area vent to get the tuning close, then use straws to fine tune it.

GM

lowlevel · 27th January 2005, 10:58 AM

A mate of mine took his new KEF speakers to a party, had ports with straws in.
Wanted to show off so had the grills off.
Was max ****ed when several people helped them selves to the straws for their drinks>

22nd January 2005, 03:40 PM	#1
bigerik diyAudio Member Join Date: Jun 2004 Location: Toronto	Tuning a port full of straws? Hi All My Seas project is built in an old ProAc Response 2 Cabinet. It is a ported cabinet, but the port is full of straws, as ProAc likes to do. Now, testing showed that the port was tuned to 50Hz, while this driver would be happier with it tuned to 45Hz. Of course, I could just remove the straws and try it the normal way, but as I have never tried a port with straws in it, it would be fun to give it a try. Anyone have any suggestions? the port is 3 inches wide, and the straws are about 6 inches or so long. Any help/suggestions would be appreciated! Thanks Erik

22nd January 2005, 05:41 PM	#4
GM diyAudio Member Join Date: Jun 2003 Location: Chamblee, Ga.	The straws makes it somewhat aperiodic, so removing them will raise Fb and increase any peaking a bit, ergo either use a smaller vent or straws or longer vent or straws or some combination of these. GM __________________ Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

22nd January 2005, 07:27 PM	#6
GM diyAudio Member Join Date: Jun 2003 Location: Chamblee, Ga.	Aperiodic means 'without ringing', i.e. there's no peaking at Fb WRT speaker damping, or sometimes referred to as critically damped, though most folks don't like it this well damped since it rolls off the bass too much for their tastes. Anyway, the straws add a certain amount of acoustic resistance like stuffing does, so longer straws or a higher quantity of smaller straws will lower Fb. Or you can make a smaller area vent to get the tuning close, then use straws to fine tune it. GM __________________ Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

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22nd January 2005, 04:38 PM	#2
Bill Fitzpatrick diyAudio Member Join Date: Jun 2001 Location: Eugene, OR	"A Port Full of Straws", what a wonderful name for a rock band.

22nd January 2005, 05:10 PM	#3
bigerik diyAudio Member Join Date: Jun 2004 Location: Toronto	LOL Does have a nice ring to it.... E

27th January 2005, 10:58 AM	#7
lowlevel diyAudio Member Join Date: Dec 2004 Location: South of Brisbane Metro, Queensland.	A mate of mine took his new KEF speakers to a party, had ports with straws in. Wanted to show off so had the grills off. Was max ****ed when several people helped them selves to the straws for their drinks>

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