how do i figure out how big i have to make the port?

[CleanSierra]

^^^ That would be a crazy amount of port!

[Krakin]

I haven't been able to, as I prefer to ready myself for college and get all of my family duties done.

But I can sight many times over multiple sources ranging from members on here, companies that pioneered the industry, the men who reinvented enclosure design, and many other people in this field of study.

Take your pick.

Let's compare port area and air to water and a hose.

Now think of a water hose, when the mouth of the hose is unblocked water will just kind of be pushed out, but if you cover a portion of the hose with your thumb then the same amount of water is being pushed through the hose with less "port area" and the water is forced to be shot out.

This will cause the water to be facing turbulence, compression, and if you apply it to an enclosure, harmonic distortion.

Same thing with a vented enclosure.

[fritosaregood]

I haven't been able to, as I prefer to ready myself for college and get all of my family duties done.

But I can sight many times over multiple sources ranging from members on here, companies that pioneered the industry, the men who reinvented enclosure design, and many other people in this field of study.

Take your pick.

Let's compare port area and air to water and a hose.

Now think of a water hose, when the mouth of the hose is unblocked water will just kind of be pushed out, but if you cover a portion of the hose with your thumb then the same amount of water is being pushed through the hose with less "port area" and the water is forced to be shot out.

This will cause the water to be facing turbulence, compression, and if you apply it to an enclosure, harmonic distortion.

Same thing with a vented enclosure.

Lets also talk about fluid dynamics then, that 5+ foot long port isn't going to be straight. Now you will have loses the system due to so many turns you have in that port, and all the friction on that 5+ foot of port length.

Its also going to end turning it into a chambered transmission line with the port that big and long.

[Krakin]

Then you should also know that forcing an amount of air through a vent that isn't large enough for it is going to cause more problems than a vent that is inconveniently long. Since virtually all of the acoustic power radiates from the vent at the tuned frequency, there is a minimum volume displacement that is required to prevent compression.

[fritosaregood]

Then you should also know that forcing an amount of air through a vent that isn't large enough for it is going to cause more problems than a vent that is inconveniently long. Since virtually all of the acoustic power radiates from the vent at the tuned frequency, there is a minimum volume displacement that is required to prevent compression.

I also know that if a port is huge, it will kill the sub under tuning. If you want an all out spl one note box, then use your huge port.

[Krakin]

You have a sharp roll off because a properly designed port should allow for a 24db slope below tuning.

[fritosaregood]

You have a sharp roll off because a properly designed port should allow for a 24db slope below tuning.

Okay, you will. You've build 1 box for a 10, I've never built a box in my life, never done spl testing on different port sizes, never build a box with more port than sub, never build box with very little port, I've never done any real world testing at all.

[mrd6]

You have a sharp roll off because a properly designed port should allow for a 24db slope below tuning.

Who desides what "proper" is?

It seems to me that this whole port area calculator thing and suggesting of excessively large ports just blew up on this site because a few guys stumbled into the formula and read some excerpts from the loudspeaker cookbook.

Just because it requires a very large port to reduce port noise and achieve a "chosen" port mach, doesn't mean that such a port is going to be best for any given application. Burp only sure. It is not uncommon for strictly numbers cars to have ports larger the cone area. But that doesn't mean it is the best choice for every daily driver situation...its not that easy, there is alot more that goes into engineering a good enclosure.

[Krakin]

Thanks for regurgitating information that I stated, I stated that I can reference detailed tests done. These tests run from the two men who set the world standard for speaker parameters, JBL a company that pioneered many technologies in the speaker industry, a man with a 35-year career working at the NASA Jet Propulsion Lab (during the Apollo era), members on here, Vance Dickason whom has contributed tremendously to the audio world, and has won many awards for his work, along with many other sources which have detailed explanations on this topic.

If you would like I can present you with links to these studies as to you can see them as well.

That being said, with the way in which a car works, you can get away with less than the recommended port area. You can even use significantly small ports for high SPL builds. It's all about the sacrifices you are will to make for your system.

[GueroZ28]

Dude you have made like 3 different threads asking the same thing...

Give me the max dimensions you have to work with and will give you all your specs and a cut list.

I know but i felt like i had to more specific.. i dont have them now cuz i lost where i wrote them down...but will tell u in the morning... Also i actually want to learn how to be able to find it myself.. so ive been looking for "explanations"