port length

[dave k]

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?

 

[SY]

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.

 

[kelticwizard]

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.

 

[SY]

KW, don't you remember that old saw about giving a man a fish?

 

[7V]

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?

 

[SY]

Hmmmm, water-filled enclosure.... 'Scuse me, gotta call my patent attorney.

 

[AudioFreak]

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."

 

[SY]

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."

 

[pinkmouse]

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.

 

[SY]

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.

 

[roddyama]

Hmmmm, water-filled enclosure.... 'Scuse me, gotta call my patent attorney.

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.

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.

BTW Dave, for the carpets sake, you might want to put the port on the top of the box.

 

[7V]

I don't know. You guys.

Throw you one little fish and you'll play with it for hours.

 

[kelticwizard]

Now we know that when someone says they have a big sub-woofer, they might well mean sub-marine.

 

[EC8010]

Port holes are fine on the side provided that they're above the water line...