port area for round port?

[realmofexcursion 0]

i talked to a rep. at DC and he said i need 17inches of port area per cubic foot of airspace. how can i tell the port area of a round port? im going to be building 4, 4" in diameter ports, that will be tuned to 33HZ. the box is going to be 5cubes when its all done. i just dont know if i i will have enough port area to keep the port noise to a minimum. any help?

[Duran 387]

Calculate the area of a circle.

[stealth 113]

pi x r squared x 4= port area for 4 4'' ports.

so just divide that number by 5.

[antonmiller 8]

lol at the topic being in advanced discussions. hahahhahahaha, but click here

[stealth 113]

fyi you should do 3 6inch ports, thatll put you up to almost 17 per.

but Round ports are more efficient than square ports. did you tell the DC rep you will be using round ports??? reason being is More air is traveling in open air than against the walls because of the ratio between sqin of port and perimeter of the port.

[realmofexcursion 0]

lol at the topic being in advanced discussions. hahahhahahaha, but click here

i hope you weren't trying to be smart about what i was asking. know how to get the basic part of the circle. but being that they need to be atleast 20 inches long each. i was trying to find out the entire area of the inside of the port. this is my first time using round ports.

[stealth 113]

oh so i believe the formula is L x pi x r squared/1728

[realmofexcursion 0]

fyi you should do 3 6inch ports, thatll put you up to almost 17 per.

but Round ports are more efficient than square ports. did you tell the DC rep you will be using round ports??? reason being is More air is traveling in open air than against the walls because of the ratio between sqin of port and perimeter of the port.

ill just probably go ahead and do the 6" ports. do you think that their will be alot of port noise?

[stealth 113]

with 17 per, there will be no audible port noise. if you go with psps, no turbulence as well.

[realmofexcursion 0]

just checked how long the ports would have to be to tune it to 33HZ. each one would have to be 37" long haha. so i think i might just have to stick to 4" diameter ports.

[stealth 113]

dude port length depends on port area. DC says 17 per and you got 10 per with the 4s. up to you

[realmofexcursion 0]

dude port length depends on port area. DC says 17 per and you got 10 per with the 4s. up to you

im just thinking of how i can fit that big of ports in the box. would it work if i put some type of elbow and extended it?

[Duran 387]

An elbow will work fine.

[slim2fattycake 85]

Man, didn't know that the area of a circle wasn't general knowledge.

[Notorious on mobile 0]

Lol for "advanced" !

Op, you'd'better make a slot porT, with L shape like most of us.

[stealth 113]

wow at this thread. all everyone is trying to do is dog on him. thats what im talking about...

and notorious get out, your 7th post is that. fukka you was only here for 2 days and a week and you already talkin shiit.

[realmofexcursion 0]

Man, didn't know that the area of a circle wasn't general knowledge.

i know how to get the area of it. but i was talking about the entire thing. lenght wise and all.

[realmofexcursion 0]

Lol for "advanced" !

Op, you'd'better make a slot porT, with L shape like most of us.

haha, i think it was pretty pathetic for everyone trying to bash. it was a simple question. i didnt know where else to put the damn thread so i stuck it there? you have a problem with it, and if you cant give me the answer im looking for then what is the point in even opening the thread?

oh. and i'd prefer round.

[BKOLFO4 29]

Which driver is it, and how much power??? XX sqin per cubic foot is a way to estimate based on the fact that a 12" normally takes ~2 ft, a 15" ~4 ft, an 18" ~7 ft, etc. I am not saying it is a bad thing - it is a nice estimate for those that cannot figure out how much port area they really need.

You actually determine port area based on the sub that will be used, the amount of power that will be used, and the tuning frequency.

It is about air velocity. I have said it many times before. . .Do you think an 18" sub with 6mm of excursion and 300 watts applied will require the same amount of port area as an 18" sub with 27mm of excursion and 3000 watts applied just because they require the same amount of net airspace? Once again, it will not hurt if the lower powered driver has the additional port area, but if space is tight, it is not required. . .

Also note that a flared PSP port does not require as much port area to operate properly vs. a non-flared round port or a slot port.

Brian

[realmofexcursion 0]

im going to be running 2 DC level 5 12s. he said that they normally dont do round ports, just slot ports. he said for every cubic foot of air, i would need atleast 17 sq inches of port area. i need atleast 85 sq. inches of port area.

[BKOLFO4 29]

(3) 4" PSP aero ports the full 17" long would work. I know people will disagree, but I remember when David from RE was doing 150's with (2) 15" MT's and (4) 4" aero's

If you do not like that idea, (2) 6" aeros is MORE than enough for a pair of 12's tuned at 33 Hz. They would have to be 24.5" long.

[slim2fattycake 85]

I'd go with the 2 6" if you have room for the length of the port. Also, you said you wanted port area not volume in the title. Volume has 3 dimensions while area has two.

[Duran 387]

Thank you for explaining that to the new members Brian! I hate that "estimation"

+1

[keetykush 34]

Why wouldn't you find the area of the cylinder, instead of just the outside circle?

[Argent Audio 54]

If you are having trouble fitting the round ports in the box just go with your standard slot port. The only ports that are going to let you get away with less port area are the ones with flares on both sides (psp-inc). With those you can get away with about half the port area of a slot or round (non flared) port.

Andrew