Online ROund Port calcs?

[bgowdy 5,000+ posts]

Net volume is the amount of volume you need after all other displacements are figured in. Therefore, if you need one cube of net volume, your sub takes up .10 cube of volume and your port for that volume takes up .25 cube of volume, then you need to design a box with 1.35 cubes of gross volume. And then, once you've built the box and the port and have installed the sub, there will be 1 cubic foot of empty space left in the box.
To say it another way and to answer your question about how do you figure port length if you don't know volume... you do know volume. If you need 1 cube net then you add all other displacements before you design the box for gross dimensions.

I don't mean to condescend because I understand that it's confusing but... it's just addition. One cube plus .1 cube plus .25 cubes is 1.35 cubes. That's your target gross volume in the example I gave.

THIS IS JUST A EXAMPLE OF HOW I TRIED TO LOOK AT IT & FIGURE IT.......

Say im wanting 4.5 cubes per sub. After measuring, i come up the with dimensions of 41-l*22-hx*23.5-deep that comes to 10.3 cubes net internal vol. say i minus the subs disp which is .38 and that comes to 9.92. I enter in that in the PSP calc. im going with 2 8in aeros and i want to tune it to 38hz. So i type in 8 for diameter and 2 for number of ports, that comes to roughly 13in each and the displ of them would be .76.

So it looks like this:

10.3 cubes net before disp

sub disp - .38

aeroport disp (2 8's @ 13in each)- .76

Net cubes after Disp =9.16 (divide that by 2 its 4.58 per sub)

If you can proofread my dyslectic attempt at this, is this correct? lol

 

[T3mpest 10+ year member]

That sounds correct from what I'm reading. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif Don't worry, box design gets easier with practice, but it's easier for some than others. Personally, I do well on the conceptual side and modeling, when it comes to actually sketching it out I tend to have more issues. I can tell you what net volume, tuning, etc, how to build it specifically is another lol. Often I end up paying a few bucks to someone just to do that for me. I tell them, here is what I need, draw it up lol. It's all practice though.