port help

[qcbangin]

if my subs call for 3 4inch ports per sub, and i want to just run either one or two large ports instead, what size large port would be equivelant? i was told that a 12inch sono-tube is too big. can anyone help?

[nCOMP1337]

I believe as long as the area of the port is equal, that is what you should be concerned with, so you would need to know the length and diameter of the smaller aero ports and then find the area by multiplying diameter by length and multiply by number of aero ports, then you would have to find 1-2 larger aero ports that is equal to or as close to equal to the area of the smaller ports

[qcbangin]

so i just need to know the area of the 6 4inch ports to come up with one number, then get one or two larger ports from that number?

I believe as long as the area of the port is equal, that is what you should be concerned with, so you would need to know the length and diameter of the smaller aero ports and then find the area by multiplying diameter by length and multiply by number of aero ports, then you would have to find 1-2 larger aero ports that is equal to or as close to equal to the area of the smaller ports

[nCOMP1337]

yea

so say 1 4 inch port is 5 inches long, the area of that port would be 20 square inches, so say you have 6 of those, thats a combined total port area of 120 square inches

so here as long as the combined total port area is 120 square inches, you should be fine

so like 2 6 inch aeros at 10 inches long would net you 120 square inches of port

this is at least how i see it, read my sig though i am a noob, it is best to allow someone else to chime in, but to me this is how the area would work and as long as the area is the same it should matter, though i do think less bigger ports are better than more smaller ports, so wanting 1 or 2 instead of 6 is a good choice

[qcbangin]

i'm a newbie, too so i'll always take any advice and suggestions i can. this is all going in a trunk. it's crazy loud now, but it can never be too loud, which is why i want to go ported. i want to hit high 140's, but hopefully low 150's. i haven't metered it, but i could already be hitting it.

[PandorasCustoms]

Might want to research this a little more. Is there any reason you are looking for a specific Port Volume?

Tuning frequency is a combination of Port Volume, Number of Ports, and Enclosure Volume.

According to the JL Audio site, they break it down like this...

The correct way to figure out how long each port should be follows this simple three-step procedure:

• Divide the chamber volume by the number of ports you wish to use for that one chamber.
• Take the quotient and use that as your Vb (box volume) in the port formula
• Do the number crunching and figure out how long each port should be

So, changing things up will have different effects on how the enclosure / speaker combination works. Are you just working off of a Manufacturer's Recommendation Sheet? If so, they are probably listing the port setup in a specific way in order to counter act Port Noise.

Also, Going with a bigger port is never "worse". It just requires less length than a smaller port.

Finally, remember if you are building your enclosure with the ports inside, exclude port displacement from the enclosure volume before calculating the tuning frequency.

Edited June 13, 2011 by PandorasCustoms

[bumonskateboard6]

Doubtful in a sealed box in a trunk on that high 140-150...What equipment do you have?

Use Torres calculator to calculate it all out or calculate it by hand with this:

Av is the area of the port so (pi*r)^2 with a round port in inches squared

Lv is the length of the port in inches

Vb is the volume of the box in cubic inches

Edited June 13, 2011 by bumonskateboard6

[qcbangin]

i'd like to hit that, but i know it will be hard in a trunk. i will say it flexes all the doors, and shakes windows when i pull in the gas stations.probably say it's cheap, but can only get what i can afford; i'm running 2 power acoustik mofo 15's on a power acoustik BAMF5500.1D. big 3 upgrade with an optima red top in trunk. i didn't really understand the formula you gave me, and can't get the torres calculator on this slow computer

Doubtful in a sealed box in a trunk on that high 140-150...What equipment do you have?

Use Torres calculator to calculate it all out or calculate it by hand with this:

Av is the area of the port so (pi*r)^2 with a round port in inches squared

Lv is the length of the port in inches

Vb is the volume of the box in cubic inches

Edited June 13, 2011 by qcbangin

[PandorasCustoms]

The formula was to assist in calculating tuning frequency. I have a spreadsheet that kind of does the same thing.

The Torres Calculator doesn't take much as far as resources to run. You sure you can't get it?

What are you running for an operating system? Anything XP or above should run it no problem. If you are running OSX or Linux, it might be another story.

[nCOMP1337]

then can you give the dimensions of the box you have or plan to have, and what ports your wanting, and what subs will go in there and what power

with the right info, someone on here can do the math for you and use torres to get the tuning your looking for