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View Full Version : Kind of a dumb question...

pdtran
02-12-2007, 10:57 PM
http://img405.imageshack.us/img405/3113/portgi0.jpg

This is a dumb question but which is the actual volume of the port if I was calculating it? Pic 1 or Pic 2?

And also when I am calculating the box size, does that include the port (total volume of the box) or without the port?

Kind of modified my existing box to get it tuned to ~38hz and trying to calculate exactly what it is at

Thanks

acold7dusta
02-12-2007, 11:00 PM
pic 2

pdtran
02-12-2007, 11:01 PM
cool thx, anyone know anything bout the 2nd question?

SEVEN_ELEVEN
02-12-2007, 11:03 PM
Subtract the volume of the port from the total volume of the box.

pdtran
02-12-2007, 11:51 PM
last dumb question
the port legnth on this be 12+3+6=21 right?

http://img411.imageshack.us/img411/4840/portyi9.jpg

working with winisd for the first time in trying to change the port to get the right tuning freq.

thx

pdtran
02-13-2007, 12:17 AM
Or would it be 12+6=18...some of you educaetd people enlighten me please

maldecido33
02-13-2007, 12:23 AM
you measure down the middle of the port, not the outside or inside edges.... how wide is it?

and the answer to the first question is neither

i'm going completely blank on the term right now, but you add 1/2 of the width of the enclosure to the port length you have in picture 2

pdtran
02-13-2007, 12:35 AM
http://img251.imageshack.us/img251/9325/portxs3.jpg

so the red line would be the actual port legnth right? that makes a lot more sense.

wow this is really difficult and confusing, lol. i bought a box from someone that advertised it as 2.5 cu. ft. @ 45hz, but after putting it in WINISD and getitng other opinions, it was more like 30.

the port used to be 2 1/4" x 13 1/2" x 31", but i took off the second wall so now it's 2 1/4" x 13 1/2" x 15". trying to see how much I should add on to get it right in the range I want. With what i have done to it i am getting like ~41 hz which is pretty close.

either way i want to change it to 37-38hz.

Trixter
02-13-2007, 06:35 AM
you measure down the middle of the port, not the outside or inside edges.... how wide is it?

and the answer to the first question is neither

i'm going completely blank on the term right now, but you add 1/2 of the width of the enclosure to the port length you have in picture 2

you mean 1/2 width of the port to it's length. (port correction factor) ;)