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Top port noise? (Read 5419 times)
HT-EXT
Ex Member



Top port noise?
03/02/06 at 11:38:48
 
Can anyone give me a list of things to check when it comes to top port noise? I have a HWK10 and HWK12 both quad load with descent speakers and the top speakers are center with the port. Both HWKs are making the same noise but mainly at high volume. Low volume they both play great and load the room pretty good. As soon as you start to crank the volume you can hardly hear the noise. Soon as you get to about 150w or so the noise is easily heard. Both boxes are dead on the specs. and the HWK's top port are slightly bigger(4 5/16 x 7) and the length adjustable. Please give me a list of ever possible thing to check so I can tinker all weekend and get these bean eat'en boxes to quit farting to the music. THANKS for any INFO.
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« Last Edit: 03/02/06 at 13:07:36 by Joe_Eaton »  
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Adrian D.
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Re: Top port noise?
Reply #1 - 03/02/06 at 13:45:21
 
use ports with really large flares
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HT-EXT
Ex Member



Re: Top port noise?
Reply #2 - 03/02/06 at 14:23:37
 
When you say flared port I thinking flared to the outside of the lid? I have heard people using flared ports that are flared on both ends. Also do I need to stay closer to the 4 x 7 port or is a little bigger going to help? Thanks for the reply ADRIAN D.
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Adrian D.
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Re: Top port noise?
Reply #3 - 03/02/06 at 15:11:45
 
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J_Rock
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Re: Top port noise?
Reply #4 - 03/02/06 at 15:49:11
 
the precision ports from PE are nice but reather expensive.  If you can swing them go for it.  


Otherwise:

http://www.users.bigpond.com/bcolliso/flares-25mm.htm
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HT-EXT
Ex Member



Re: Top port noise?
Reply #5 - 03/02/06 at 17:11:44
 
THANKS J ROCK and ADRIAN D for the info. I have already order the PE flared ports and can't wait to get start on the new port design. Appericate the replies and will try to let you know about the progress. Oh yeah now that I am going with the flared ports do I still use the standard measurements. I read something about the two bottom ports would need to be 3" x 4" and if that is the case the top should be 4" x 8" with flares on both ends of the port. Sorry to be a pain I just want to do the design right the first time. THANKS for your TIME.                                                                  HT-EXT
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« Last Edit: 03/02/06 at 17:27:40 by Joe_Eaton »  
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J_Rock
Ex Member



Re: Top port noise?
Reply #6 - 03/02/06 at 18:53:02
 
the diameter needs to be the same for sure.  As far as length I will have to get back to you, but I believe they overall need to be shorter.  The flare is take into account.
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Adrian D.
Ex Member



Re: Top port noise?
Reply #7 - 03/03/06 at 13:03:48
 
with the flares you have to take into account the "coanda" effect. coanda was a romanian plane builder and he built the first jet-powered plane. he studied why fluids (as air) move along a surface close to them.
leaving the history stuff away, i think you could make the whole port a bit shorter. but keeping it as long as it would be without the flares just lowers the tuning.
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HT-EXT
Ex Member



Re: Top port noise?
Reply #8 - 03/03/06 at 16:17:26
 
So if I measure from the end of the flare to the other end of the flare I should use the standard measurements(HWK10 4" x 7" and HWK12 4" x 8"). Now I measuring from the lip of each flare not where the flare shrinks down to 4". Do you think this would be a be a good place to start? I will haft to test different lengths ports for my set up but I was needing a good place to start. Besides its easier to cut stuff off than add stuff back to the port. THANKS for the REPLYS.
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J_Rock
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Re: Top port noise?
Reply #9 - 03/03/06 at 16:39:37
 
A flared port shares part of the air in the flare with the surrounding air, meaning that the port appears shorter.

The generally accepted adjustment is to subtract half the flare radius from the physical length to obtain the acoustic length. If both ends of the port are flared, the adjustment is done for each flare.


from this site:
http://www.users.bigpond.com/bcolliso/port-flares.htm

guy seems to know very much about ports.
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HT-EXT
Ex Member



Re: Top port noise?
Reply #10 - 03/03/06 at 16:50:51
 
The site is KIILER! It gives me all kinds of ideas. Do you think some polyfill in the center chamber would help? Thanks for the info. It helps point me in the right direction and own my own I have been lost most of my life. I don't suppose Decware has a lost and found section?  DUH-HUH
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Adrian D.
Ex Member



Re: Top port noise?
Reply #11 - 03/04/06 at 17:29:44
 
polyfill helping with port noise ? i guess it can, because it kinda restricts the air movement.
if it really reduces air speed AND port noise, it should be used in the chamber with port noise problems.
imo, none of steve's design need polyfill
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Wreckinthehouse
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Re: Top port noise?
Reply #12 - 03/07/06 at 01:11:10
 
HT-EXT,
  I added 1" of standard foam to the underside of my top chamber with favorable results. I cant say that it helped with port noise, because i flared mine from the beginning and never had any. That being said, I think the the sound coming from the port sounds smoother and absorbs some of the ring from the plywood.
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HT-EXT
Ex Member



Re: Top port noise?
Reply #13 - 03/08/06 at 15:29:18
 
SUCCESS! The HWK10 no longer has gas problems and the best thing was I used the cheapest port possible(PE #260-403). I used two 4" flared ports with a coupler in the middle. Overall length is about 7" from outside flare lip to outside flare lip. I have been able to put 250w to about 350w to the HWK with no port noise. After +350w I start hearing the little man with a hammer inside the box but still no port noise. Thanks for all the help and I am looking foward to starting on the HWK12. NO MORE BEANS FOR DEZZZ HWKS!   HT-EXT
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Bob
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Re: Top port noise?
Reply #14 - 03/08/06 at 22:57:19
 
HEY  Wreckinthehouse, I would like to talk to you about that plywood ring you mentioned. I though the embarrasing affliction my HWK has was too difficult to explain on a post, so of course if I ignore it, it'll go away, right?  So, adding foam to the inside top is all I (may) need to do to get that sick ringing gone?

Bob
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