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Port noise


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13 replies to this topic

#1 of 14 OFFLINE   Frank Kanyak

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Posted May 15 2002 - 12:52 PM

Is there any solution to control my port noise at during some intense scenes. I did do a search in the DIY to no avail. It sounds like a chuffing like someelse said. ^' port x 26" length.
Denon 2805,Monster MK II 5000 Power Center,Logitech 880 Remote Control, JBL S-center, JBL S412p, JBL S26, JBL L1, Tempest Sonosub(tuned to the sweet sound of 16.5 hz). :-)
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#2 of 14 OFFLINE   Chris Tsutsui

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Posted May 15 2002 - 01:24 PM

26" is pretty long, is there a shorter length alternative?

Are your ports flared? I found that my two 11" flared ports create no noticeable air noise. (Unless I run a test tone and listen close to the ports)


#3 of 14 OFFLINE   Greg Monfort

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Posted May 15 2002 - 04:33 PM

You can stretch grill cloth (or similar) over the vent, turning it towards Aperiodic. Peak vent output will drop a little. If one layer isn't enough, then try two, but the main thing is getting it tight. Once you have the right amount, make a frame to attach it to, and to the sub.

BTW, this improves transient response too, though how audible it will be I can't say.

GM
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#4 of 14 OFFLINE   Ron Shaw

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Posted May 16 2002 - 03:48 AM

Port noise is caused by the port area being too small. The velocity in the port should be kept below Mach .2 in order for port noise to be inaudible. Increase the area (diameter) of your port. You will need to increase its length to keep the tuning the same.

#5 of 14 OFFLINE   Dave Poehlman

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Posted May 16 2002 - 04:27 AM


Is it a DIY sub, Frank?

Flaring the port may help. Widening or doubling your port will definately help. As stated above.. you would have to rethink the length of your port(s) if you want to keep the same tuning.

If it is a DIY sub and you are using PVC pipe.. make sure the ends are cut smooth.. sometime a burr or rough cut can cause noise.

#6 of 14 ONLINE   Patrick Sun

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Posted May 16 2002 - 07:00 AM

I'm guessing Frank is using 6" wide port. That should be wide enough.
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#7 of 14 OFFLINE   Brian Bunge

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Posted May 16 2002 - 07:17 AM

Pat,

So how was the movie! Posted Image

Brian
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#8 of 14 OFFLINE   Dave Poehlman

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Posted May 16 2002 - 07:57 AM

Quote:
I'm guessing Frank is using 6" wide port. That should be wide enough.


Agreed. But 26" does sound pretty long. I think we need more details, Frank. What kind of driver is it and what is the size of your enclosure?

#9 of 14 ONLINE   Patrick Sun

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Posted May 16 2002 - 08:01 AM

Brian,

http://www.hometheat....422#post694422

(Now we return you back to port noise).
"Jee-sus, it's like Iwo Jima out there" - Roger Sterling on "Mad Men"
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#10 of 14 OFFLINE   Frank Kanyak

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Posted May 16 2002 - 11:33 AM

http://frank18202.tr....ion/index.html

here's the link to my setup...Thanks for the responses I still don't know how to go about solving this problem. BTW the port is made out of 1/2 thick cardcard board tubing.
Denon 2805,Monster MK II 5000 Power Center,Logitech 880 Remote Control, JBL S-center, JBL S412p, JBL S26, JBL L1, Tempest Sonosub(tuned to the sweet sound of 16.5 hz). :-)
Panasonic L300U projecting onto Carada Classic Cinema White 88"

#11 of 14 OFFLINE   Greg Monfort

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Posted May 16 2002 - 12:23 PM

Well, you can stick a longer 6" tube in, but it'll probably need to be ~45" long to be effective, or you can double up or stick a larger one in, which will make it (them) even longer. Not good plans IMO, so this leaves either my suggestion, a combination of my suggestion and make it a little longer, or seal it up.

GM
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#12 of 14 OFFLINE   Frank Kanyak

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Posted May 16 2002 - 01:02 PM

If I redo my endcap(meaning not having a port) will it play louder and deeper or just the opposite?
Denon 2805,Monster MK II 5000 Power Center,Logitech 880 Remote Control, JBL S-center, JBL S412p, JBL S26, JBL L1, Tempest Sonosub(tuned to the sweet sound of 16.5 hz). :-)
Panasonic L300U projecting onto Carada Classic Cinema White 88"

#13 of 14 OFFLINE   Greg Monfort

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Posted May 16 2002 - 01:26 PM

Just the opposite unless you accept the higher distortion of increased excursion, though frankly it will be low enough in frequency that overall it may sound better.

GM
Loud Is Beautiful, If It's Clean

#14 of 14 ONLINE   Patrick Sun

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Posted May 16 2002 - 01:26 PM

The opposite.
"Jee-sus, it's like Iwo Jima out there" - Roger Sterling on "Mad Men"
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