port turbulent jet noise. any advice?

[Artmaster]

problem appear.
narrow port tube. 75mm. 25 centimeter length. I wont make it bigger. 32 litre cube box. 10" driver.
any form of port tube: round, square, egg-glass makes noise.
anybody, who know this problem, help me please.

[johninCR]

What kind of flares have you tried on the ends of the port?

[Artmaster]

basicaly - nothing. I mean it's just pipe port. it's easy, but i tried to use cone, rectangular, egg-glass port. without success.
noise exist on conditions big output power.
I think this noise has stream turbulence nature.
it's appear on appointed frequency and output power.
today, I'll try to segregate port inside to 2 or 4 section.
will see

[BillFitzmaurice]

You can only push so much air though a port of given diameter before it will make noise. You can use flared ends or you can make the port a larger diameter. The only other option is finding a way to change the speed of sound.

[rdf]

Take a look at this: http://www.carstereo.com/help/Articles.cfm?id=21

[BillFitzmaurice]

http://www.carstereo.com/help/Articles.cfm?id=21

Informative, yes, but way too much work. All you have to do is model the box in WinISD and it will not only figure the correct vent and box size but will also tell you if the vent mach is too high.

[Artmaster]

oh! thank you gentlemen!
it's ok. I knew it, but I wouldnt make port bigger diam., or few pcs of port.
I wish to get nice result using anyone another way. and I'm sure - it's possible.
that's why I ask all of you about it.

[Ron E]

You need a flared port, or a bigger (and longer) one

http://www.madisound.com/nht10subkit.html

The flare (a trumpet bell shaped zone on the inner and outer ends of the port) smooths the transition regions of flow and makes the port quieter.

You can alternatively try to fill the port with straws, but that will also reduce output.....

[Artmaster]

thank you, Ron E, but I'm looking for new, science solution.
I'm sure it's exist.
I can follow traditional method's, but should I make port smaller, I'll get distortion on another frequency.
it's maybe not big level, but anyway it's ahould be.....
I wont have it
I want to make ideal system, using available facility.
I think future system will get rid this problem, but I wanna do it now.
thank you again. we're make common masterpiece

[johninCR]

Originally posted by Yury
... but I'm looking for new, science solution.
I'm sure it's exist.....

Yury,

Let us know if you are able to change some of the laws of physics, because I'm sure we can come up with a few we'd like to change.