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View Full Version : Online ROund Port calcs?



bgowdy31
10-21-2013, 07:30 PM
Im trying to work with these and figure out how its actually used. Like take the 12volt.com or Precision Port Sounds(PSP) calcs. They ask for the enclosures net volume before i know the aeroport displacement.

Are these calcs asking for Internal volume net ""BEFORE DISP""? it may be a noob question but not sure i understand it.

SMS
10-21-2013, 08:09 PM
yes they are

bgowdy31
10-21-2013, 08:21 PM
yes they are

thank ive tried it before but never asked even tho i didnt understand but this time i figured i would

SMS
10-21-2013, 08:29 PM
nope, sorry i read that wrong here lookin for you to put in the net volume after all deductions.... sorry bout that

bbeljefe
10-22-2013, 02:11 AM
Loudspeaker calculators and programs deal in net volume after displacements. So... find your tuning at a given volume and then add all displacements to calculate gross enclosure volume.

bgowdy31
10-23-2013, 09:08 PM
Loudspeaker calculators and programs deal in net volume after displacements. So... find your tuning at a given volume and then add all displacements to calculate gross enclosure volume.

really? honestly that kind of doesnt make since but it does at the same time. lol i know.... see now im kind of confused on how to do this

basswiigee
10-23-2013, 09:10 PM
really? honestly that kind of doesnt make since but it does at the same time. lol i know.... see now im kind of confused on how to do this

lmao yup i'm too confused too... good luck bgowdy!!!

bgowdy31
10-23-2013, 09:13 PM
Loudspeaker calculators and programs deal in net volume after displacements. So... find your tuning at a given volume and then add all displacements to calculate gross enclosure volume.


what do you mean by this?

bgowdy31
10-23-2013, 09:20 PM
lmao yup i'm too confused too... good luck bgowdy!!!

idk if your being sarcastic, but to me it doesnt make sense to put in net volume after disp to get the lenths of ports.

basswiigee
10-23-2013, 09:26 PM
idk if your being sarcastic, but to me it doesnt make sense to put in net volume after disp to get the lenths of ports.

no bro wasn't being sarcastic.. seriously your talking rocket science to me, lol i got to put my trust into someone with the know how... i do alright with torres but sketch up makes me wanna break stuff... so no personally made boxes in my future... i do wish you luck, cuz seriously i was trying to follow thread but got lost...

bgowdy31
10-23-2013, 09:31 PM
no bro wasn't being sarcastic.. seriously your talking rocket science to me, lol i got to put my trust into someone with the know how... i do alright with torres but sketch up makes me wanna break stuff... so no personally made boxes in my future... i do wish you luck, cuz seriously i was trying to follow thread but got lost...

Yea i know......... How the hell can you figure the lenths or ports with the net cubes of the box when you dont even know the port displacement with out the lengths of them yet....? make sense lol

basswiigee
10-23-2013, 09:33 PM
lmao... there i go lost again lol seriously good luck bro...

bgowdy31
10-23-2013, 09:48 PM
lmao... there i go lost again lol seriously good luck bro...

i just found something that says you the the volume of the box minus the subwoofer displacement

bbeljefe
10-23-2013, 10:33 PM
what do you mean by this?


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. :-)

bgowdy31
10-23-2013, 11:26 PM
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. :-)

so i seems i do it the same way just kind of backwards

bgowdy31
10-24-2013, 12:06 AM
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
10-28-2013, 05:19 PM
That sounds correct from what I'm reading. :) 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.