porting an interveted sub

[evo2k3 10+ year member]

first off sorry mwess....i snapped i was in a bad mood //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif anyways back to the topic....i just got this winisd pro to do some calcs for me, and do people leave all the defaults for air pressure, humidity, should i put in the actuall peak power the sub is getting? i ask because it its showing me a air vel. of 1200 ft/s which is like 390m/s, well over the 30m/s recomendation....somehow i think i did something wrong....btw its a 12w7 in a 1.95cu ft box. tuned to 32hz...in that program, is the crossectional area, the same as what you refer to as port area? i would assume soooo.

 

[evo2k3 10+ year member]

ok i was looking at the wrong thing...i went to the rear chamber port air velocity, now i want the peak of that graph under 30 m/s (98.4 ft/s) right? if it gets really close to that, or a little above, is it going to make a huge diference? or might i get port noise every now and then? for example, 2 3" ports keeps the lengths to resonable sizes, but puts the vel. at 38 m/s...this just simplifies everything for me, how much port noise is going to be seen in that scenario?

 

[evo2k3 10+ year member]

im not sure how i have to take that in acount....are you familar with winis pro? i just entered the volume before ports displacment and played with the port diamter and number of ports.....is the program taking it in acount, or do i need to do something else? also i want to just use pvc (3") so i have access to right angles and such, but how or what do i use for a flange on the surface? with quite length ports i am afraid they are going to rattle against the box, is this a legit conern, should i ankor them inside somehow? remmeber...this is my first shot at porting.

 

[evo2k3 10+ year member]

well im not changing the tunning freq ever....its going to be 32hz....are you saying the total displacment for the ports (no matter what combination of size and length i use) is always going to be the same in the same volume box? if so what is it? also i can i take that in acount, as the volume changes, the port length change, which then changes the volume again....seems cirular, what am i missing?

 

[evo2k3 10+ year member]

ok...so the program is useless for port length basicly right? how do i calulated the length needed then?

 

[evo2k3 10+ year member]

Originally posted by Jmac I can do it for you //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif I don't have an equation for it, unfortunately, but I do have a professional program that does it accurately //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

All I need are the exterior dimensions of the box, width of wood, and port size (2 x 3" ports, right ?) //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

box is in construction so ill give them to you tommorow...whats the proessional program? how much it cost you, i might be intrested. you dont actully need to dimmensions, wont the volume be sufficeient? i ask because its a rather odd shape...ill post a diagram tommorow.