port turbulent jet noise. any advice?

[Artmaster]

Your vent should be flared on both ends to perform at its best.

Another way to reduce port noise which has not been mentioned is to use a rumble filter. This reduces the velocity further and can make a big difference.

is it realy work? I never made it before. ok. thank you. I'll try.

about rumble filter. do you mean low-pass filter? I have it. 12 db/oct. 12-14 hz. wont make it higher.
and no another filters. anyones. it's always make sound poor

 

[paulspencer]

yes flaring on both ends does work!

No, a rumble filter is a highpass filter. A good rumble filter would be at least 4th order and preferably 6th order @ 20 Hz.

 

[Artmaster]

oh! sorry. my mistake. course - highpass filter. I have it.
ok. I'll try to make flared on both ends port will see

 

[paulspencer]

a few ways to do it:

1. make a template and apply heat to the PVC vent and push it so that it stretches - you can get a small radius this way

2. attach to MDF and use a router bit eg. one inch

3. turn up a larger flare on the lathe

 

[Artmaster]

a few ways to do it:

2. attach to MDF and use a router bit eg. one inch

explain please

 

[paulspencer]

you attach the vent (PVC) to MDF into which is cut a hole. You then attach this to the baffle on the outside. You use a router bit to get a radius on the outside edge.

 

[noodle_snacks]

I used the router method and it works quite well. Take it very slowly with the PVC pipe and use a fairly powerful router as the PVC is generally quite a bit harder than wood. Once you have done it you can fill any small gaps that have been made with putty etc.

 

[paulspencer]

It's not necessary to cut through the vent with the router if you use a separate mounting ring, which is in fact an easier way to make the vent presentable.

 

[Artmaster]

thank's for picture, paulspencer! it's easy for understanding.
pity, but even egg-glass port with exponential borders couldn't sound well. it's has lot of distortion, cutting-off effects. less a little then simple pipe.

that's right. I can't change law of physics.
but I realy get acceptable quality level with smaller port diam - 50 mm instead 75 mm, 100 mm, 2 pcs of ports diam 75 mm.

probaly it's ok for me, but I'll test any more ideas

 

[noodle_snacks]

If the noise is still a problem when playing music/movies or whatever (Port noise with sine-waves isn't really anything to worry about) then try stuffing the port slightly with some sort of acoustic stuffing like polyfill or dacron. The output of the port will be reduced but so will port noise.

 

[Artmaster]

I'm afraid - it's not exactly
noise exist anywhere. sine, music signal - have not difference.
you're right. should I cover tube of port inside demping material, noise decreased.
ok. looking for the best way again

 

[noodle_snacks]

Try some stuffing. You can get it from any material shop pretty much (ask for pillow stuffing etc) and see what the results are, you can experiment with varying amounts until the port noise is gone. If stuffing the port rolls off bass response too much and you can think of no other options you might consider converting it to sealed and adding a powered subwoofer to do the bass instead.

 

[Artmaster]

thank you noodle_snacks!
I'll experimenting again and again. of course, I can add any power to sub, but it'll add noise either.
now i try to unload of noise for nominal power for my 10" driver.
it's about 86 db. it's a little output, but it's enough for me.