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 Multi-Way Conventional loudspeakers with crossovers

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 13th July 2003, 05:33 AM #1 dave k   diyAudio Member   Join Date: May 2003 Location: B.C port lenght need help.the project requires a port of 2.5 dia and 4 inches long.i can get a port of only 2" dia, but what leght shoud it be?
 13th July 2003, 06:22 AM #2 SY   On Hiatus     Join Date: Oct 2002 Location: Chicagoland dave, the general vent formula for a flush mounted vent is: L = {(1.463x10e07xR^2)/(fb^2xVb)} - 1.463R where L is length, fb is box tuning frequency, R is port radius in inches, and "^" is exponentiation. The algebra should be pretty straightforward. __________________ "You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."
 13th July 2003, 07:12 AM #3 kelticwizard   Wizard of Kelts diyAudio Moderator Emeritus   Join Date: Sep 2001 Location: Connecticut, The Nutmeg State Or you can run a quick simulation on WinISD to find that the length of the 2" tube should be 2.29 inches long to equal a 2.5" tube 4 inches long. __________________ "A friend will help you move. A really good friend will help you move a body." -Anonymous
 13th July 2003, 01:08 PM #4 SY   On Hiatus     Join Date: Oct 2002 Location: Chicagoland KW, don't you remember that old saw about giving a man a fish? __________________ "You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."
7V
diyAudio Member

Join Date: Feb 2003
Location: North London
Quote:
 Originally posted by SY KW, don't you remember that old saw about giving a man a fish?
How big should the fish be and should the water just be in the port or does the bottom of the enclosure need to be filled as well?

 13th July 2003, 01:19 PM #6 SY   On Hiatus     Join Date: Oct 2002 Location: Chicagoland Hmmmm, water-filled enclosure.... 'Scuse me, gotta call my patent attorney. __________________ "You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."
 13th July 2003, 01:20 PM #7 AudioFreak   Warp Engineer On Holiday     Join Date: Oct 2001 Location: Queensland, Australia 7V, I'm sure this is a moot point but I believe SY was referring to the old adage "Give a man a fish, feed him for a day; Teach a man to fish, feed him for a lifetime." __________________ - Dan
 13th July 2003, 01:22 PM #8 SY   On Hiatus     Join Date: Oct 2002 Location: Chicagoland I think Steve got it, but the adage I was thinking of goes, "Give a man a fish and you feed him for a day. Teach him to fish and he'll sit in a boat all day drinking beer." __________________ "You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."
pinkmouse
diyAudio Moderator

Join Date: Apr 2002
Location: Rotherham, England
Quote:
 Originally posted by 7V How big should the fish be and should the water just be in the port or does the bottom of the enclosure need to be filled as well?
I think what SY is suggesting is a cunning variable damping system, the water filled box providing a stiff coupling system to the driver, with the fish causing variable damping due to two factors. Their bodies will act to break up large scale standing waves, (depending on the size/age of the fish), and the eddies in the water caused by their movement providing micro diffraction to reduce high frequency resonances.
__________________
Rick: Oh Cliff / Sometimes it must be difficult not to feel as if / You really are a cliff / when fascists keep trying to push you over it! / Are they the lemmings / Or are you, Cliff? / Or are you Cliff?

 13th July 2003, 01:29 PM #10 SY   On Hiatus     Join Date: Oct 2002 Location: Chicagoland By means of implanted electrodes in the fish, you can actually use them to provide motive force to the cones each time you administer a shock. Or you can use the shock/wiggle technique, carefully phased, to provide damping. PETA might have a problem with this, though. Then again, water dampens everything. Sorry, I'll behave now. __________________ "You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."

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