Port noise..

[miker 5,000+ posts]

What is it and where does it come from?

Also what makes certain woofers adapt to certain tuning frequency's?

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[Immacomputer 10+ year member]

It comes from eddy currents due to high wind speed in the port. This is known as turbulence and it's basically a swirling type motion of the air inside the port. This causes a "whooshing" noise that comes from the port and keeps the port from performing at it's optimum output levels.

High port velocity (high wind speed in basic terms) is causes from too little port area. Around the tuning of the enclosure, the two dimensional port area acts like a radiating surface (like the cone of your speakers) and the column of air moves back and forth as the air inside the enclosure pushes and pulls on it. The louder you get, the farther and farther that the air in the port needs to travel. If you push it too far, the air will be moving too fast and it won't be able to change directions quickly enough which will cause turbulence and port noise.

Your application is really what should decide the tuning frequency. Thiele/Small parameters will help you find that but it's really up to what you want out of your system.

 

[skadude016 5,000+ posts]

to little port area. to skinny of a port.

certain woofers like certain tuning freq's because of how the woofer is made and its T/S parameters. and also the vehicle it is in //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[miker 5,000+ posts]

So.. How do you know how wide you want your port?

 

[atlninja82 10+ year member]

it depends on your sub and its t/s parameters. there are certain programs that will tell you the recomended port dimensions for a certain enclosure volume. also you could probably email the company and ask them. im sure some more knowledgeable people on this forum could tell you more.

hope this helps,

-eric