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Old 21st October 2004, 03:37 PM   #1
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Default port noise minimise

hello all!
nice to get sub forum.
I wont make port bigger then 70 mm, but it's very noisy. lot of distortion.
could anyone help me solve this problem?
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Old 21st October 2004, 04:46 PM   #2
m4dm4n is offline m4dm4n  Sweden
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do you got flared ends?
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Old 21st October 2004, 05:02 PM   #3
Ron E is offline Ron E  United States
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IIRC you asked this question a few weeks ago.
port turbulent jet noise. any advice?

I guess I am not clear on what you call "distortion" and why you think making a bigger port would only change the frequency of distortion.

Post your T/S parameters and box design so people can model it and decide how realistic your expectations are. What is the power input that it starts occurring at?

Observations:
If your port is making that much noise, you probably would make more and cleaner SPL at that power input with a sealed box.

If you can't fit a larger diameter port, use a Passive Radiator.
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Old 22nd October 2004, 04:03 AM   #4
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Ron, I saw and replied to the same post. He wouldn't accept the simple facts of the matter then and I doubt if he will now. For the last time, Yury, make the port bigger or live with the noise. The physics of vented box loudspeakers haven't changed all that much in the last four weeks.
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Old 22nd October 2004, 06:24 AM   #5
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gentlemen!
forgive me for recurring post. it's just a new place for sub talk. and I decide asl society again.

well, dear m4dm4n, frared port done, I tried use it. without success. the same as egg glass port and several ports more.

my driver has: Fs 33hz
Pmax - 400W RMS
sensitivity- 88 db
Re - 4 ohm
effectiveness -0.36
Qts -0.39
Vas vent - 29-39L

I use box 27L inside, 35*35*35cm marble cube.
port 75mm, length - 250 mm
L=(2354*D^2/VF^2)-085D, so it's have be tuned to 40 hz.
it's ok for me, but noise!!!
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Old 22nd October 2004, 07:50 AM   #6
foo is offline foo  Tibet
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use a lager enclosure might do .
however, it also affect the Q ratio ...
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Old 22nd October 2004, 10:15 AM   #7
m4dm4n is offline m4dm4n  Sweden
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Well i've heard that rektangular ports should help also. Try this=
Vent 31.8cm wide x 1.6cm high (assuming your cube is 350mm and use 16mm MDF), and flare the ends also.
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Old 22nd October 2004, 10:31 AM   #8
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Quote:
Originally posted by m4dm4n
Vent 31.8cm wide x 1.6cm high (assuming your cube is 350mm and use 16mm MDF), and flare the ends also.

you're advise me different parametrs for port tuning.
should I make this, I'll get another F for system
however, I was try it before. sound- the same like round port.
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Old 22nd October 2004, 10:41 AM   #9
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ok. tomorrow I'll segregate my round port to section.
I mean lengthways pipe inside. will see.
I asked physicist theorists from Moscow University about flow turbulence problem. how can I get rid of this....
I hope they will offer me something. they always make it for spaceships and jet airplanes. let's help me now
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Old 22nd October 2004, 01:08 PM   #10
m4dm4n is offline m4dm4n  Sweden
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It will be nice to hear what they have to say about flow turbulence problems.
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