optimal "musical" port area for SP4?

[ncc74656]

i followed the instructions on

http://www.hometheatershack.com/forums/diy-subwoofers-general-discussion/6330-winisd-pro-tutorial-download-detailed-guide-how-use-winisd-pro.html

the auto calculated values come up so far off from what Fi lists... what am i doing wrong?

[Kevin M]

The Qes and Qts don't look right. Looks like you have an extra zero on the right side of the decimal. Looks like they have a monster suspension. You could use those in a home setup as a dipole or open baffle even.

[ncc74656]

i think i got it now, i found another guide that listed a different order to enter parameters and it seems to be much better now. this is the one i used:

http://www.diyaudio.com/forums/subwoofers/148729-how-correctly-use-winisd.html

[SLAYER1805]

i understand that xmax and vas and other specs play into the port area required for the sub. I used a website that listed me needing a 167 minimum port area but it is using 70%BL to determine that, what ever that means. i have been told that i need to base my port area off of more than just that spec so im trying to determine exactly how to do that. perhaps the question i should ask is what would be an optimal velocity for the port air? this website asks for more specs so id assume its more accurate thant he first one i tried:

http://www.bitpusher.in/?p=portarea

if frequency response does not play into the port area why do people say my "musical" ability of the box will be crap if i have to much port? is that not effecting frequency?

My cousin designed that calculator lol

[DylanBunch]

Also the fs is wrong and the bl is wrong

[ncc74656]

im getting better results from win ISD now that i entered the info in a different order. it was auto calculating the incorrect BL and FS so i had no idea how to fix that. turns out you need to enter the info in a very specific order or the program wiggs out.

that air flow calculator is pretty handy. win isd is telling me that ive got a max of 20.2m/s air flow. if i have rounded port edges will that create port noise? 99.75 inches squared of area and 28.5 x 3.5" port.

[Joe X]

WinISD does not account for cabin effects, it gives about the response you would get in an anechoic chamber or outdoors.

[ncc74656]

ooooo um... so the speed of the air of an unloaded port is what the program will give me, if i face it at a door or ceiling then things will change. right? how should i adjust hte numbers the program is giving me? what impact will this difference have on the box design and sub performance?

i currently intend to face the sub and port forward with out a wall to load off of. they would both have about 5 feet of space from the face of the sub/port to the nearest object.