Calculating Round Ports

[thebiggmann12 14]

OK, so I've decided to try out a box using round ports for my 18" nightshade, so i can make the ports interchangeable for comps and daily. I'm using a Hifonics Brutus 1600d amp. i figure the box should be about 5 cubes since the amp isn't that powerful and i want to get a lot of output. i want to use 2 6" diameter pieces of PVC. i am going to do some testing to figure out where my port should be tuned at for spl, but my question is that if i want to keep the box at 5 cubes how big should i make it to make sure its still 5 cubes after the displacement of the ports? i have been looking all night trying to figure this out. i found that if my box is 5 cubes i should use 2 6" x 23.6" to get the tuning to 33 Hz, but would putting the ports in the box change the tuning because it makes the volume smaller? also, i found that the square port area will be 111 cubic inches...is that too much? or too little? or just right? lol idk this round port tuning has me all confused. any help would be greatly appreciated. thanx.

[Duran 387]

Yes the displacement of the port will affect tuning. For SPL, meaning one not only, that port area will work well. For daily it is WAY too high, the highest I would go is 80 in²

Why are you talking square ports when your asking about round ports, are you going to have both in the same enclosure?

[thebiggmann12 14]

Yes the displacement of the port will affect tuning. For SPL, meaning one not only, that port area will work well. For daily it is WAY too high, the highest I would go is 80 in²

Why are you talking square ports when your asking about round ports, are you going to have both in the same enclosure?

no sorry about that i meant port area will be 111 cubic inches...and thats my thing it gave me cubic inches not square inches...

[Duran 387]

Yes the displacement of the port will affect tuning. For SPL, meaning one not only, that port area will work well. For daily it is WAY too high, the highest I would go is 80 in²

Why are you talking square ports when your asking about round ports, are you going to have both in the same enclosure?

no sorry about that i meant port area will be 111 cubic inches...and thats my thing it gave me cubic inches not square inches...

So that's the port displacement, not port area, right?

[thebiggmann12 14]

no, the calculator asks me for the length and the diameter and then i punch those numbers in and it says total port volume and then it give me 111 inches cubed.

[Duran 387]

no, the calculator asks me for the length and the diameter and then i punch those numbers in and it says total port volume and then it give me 111 inches cubed.

Port volume is the amount of space in the port, not port area.

(LxW) x 6 = Surface area

LxWxH = Volume

[thebiggmann12 14]

lol im soo confused...im messing with this other calculator that gives me the displacements and everything all in one..i think my problem might be solved.

[thebiggmann12 14]

OK how does this sound? Box will be 33w x 20h x 20d speaker displacement is .26. I will tune to 33hz and 41 Hz using 6" diameter PVC. Tuning to 33hz will be 5.255 cubes and will use 2 6"s at 22.131 inches long each and the 41hz tuning will be 4.815 cubes and will use 3 6"s at 23.745 inches long each. does this sound alright? Anything i should do differently? Volume is after all displacements. Yes i know the ports will stick out the top of the box a bit, no biggie...BTW I'm doing sub up port up.

[KU40 173]

If your amp isn't too powerful, you should increase box size to increase the efficiency of the setup.

[thebiggmann12 14]

well i plan on getting a better alt and some batteries soon and then a bigger amp...other than wattage and size does it look correct?

[B7L|BL4Z3R 4]

when you have small amp you want a larger box.. and the other way around for a large amp

[thebiggmann12 14]

yea i plan on running a 1500d or a 2000d to it soon hopefully. u think the box would work good with one of those amps?