Welcome, Guest. Please Login or Register
Decware Audio Forums
08/01/14 at 11:05:06


Pages: 1 
Send Topic Print
Top port noise? (Read 5712 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.
Back to top
 
« Last Edit: 03/02/06 at 13:07:36 by Joe_Eaton »  
  IP Logged
Adrian D.
Ex Member



Re: Top port noise?
Reply #1 - 03/02/06 at 13:45:21
 
use ports with really large flares
Back to top
 
 
  IP Logged
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.
Back to top
 
 
  IP Logged
Adrian D.
Ex Member



Re: Top port noise?
Reply #3 - 03/02/06 at 15:11:45
 
Back to top
 
 
  IP Logged
J_Rock
Ex Member



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
Back to top
 
 
  IP Logged
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
Back to top
 
« Last Edit: 03/02/06 at 17:27:40 by Joe_Eaton »  
  IP Logged
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.
Back to top
 
 
  IP Logged
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.
Back to top
 
 
  IP Logged
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.
Back to top
 
 
  IP Logged
J_Rock
Ex Member



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.
Back to top
 
 
  IP Logged
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
Back to top
 
 
  IP Logged
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
Back to top
 
 
  IP Logged
Wreckinthehouse
Ex Member



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.
Back to top
 
 
  IP Logged
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
Back to top
 
 
  IP Logged
Bob
Ex Member



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
Back to top
 
 
  IP Logged
Wreckinthehouse
Ex Member



Re: Top port noise?
Reply #15 - 03/10/06 at 00:11:39
 
The ringing that I mentioned is a trade off that you have to deal with when using plywood. I would rather use MDF but because of the weight, the plywood is the way to go. This ringing is the reason that you wont find any serious car enthusiast's using plywood. I suppose if you can afford top dollar 13 ply plywood that you nay not have this problem, but i find that the foam on the inside of the lid does the trick.
Back to top
 
 
  IP Logged
gexter
Ex Member



Re: Top port noise?
Reply #16 - 03/10/06 at 01:58:26
 
use something like dynamat on the sides and the basket. this helps the ringing.

The multiple layer ply is better but stuff like baltic birch even in a 5 or 6 ply is better than fir or spruce.

IMHO

PS glad you got the Port thing worked out..    did the dimensions of the port change from the original?... I was wondering if it was the port itself.  
because it was adjustable I was wondering if it was that design that was the problem.

the port design of the HWK is generic but TS parameters are unique to the driver creating problems with some drivers and not others.
I swapped four types of 8" drivers in a HWK for fun because my original had port noise. the result was the drivers made a differance.




Back to top
 
 
  IP Logged
Bob
Ex Member



Re: Top port noise?
Reply #17 - 03/10/06 at 12:18:43
 
Wreckinthehouse, I actually used particle board (3/4") not quite MDF, but I would think better than plywood acustially, maybe? Weight isn't so much of a concern for me since once placement is set, weights not a factor anymore. Correct me if I'm wrong, but I thought weight, mass, ridgidity, strenth were all desireable traights {sp}. And an extra 50lbs would be a good thing? (other than the obvious problem of assembling the heavy monster.)

As far as material on the inside, I work at a Chevrolet dealership in the service department. We have automotive carpet padding in bulk rolls. Looks like like Dynamat, would this be a good thing to line the inside of upper and lower chambers with?

Bob
Back to top
 
 
  IP Logged
DirtDawg
Ex Member



Re: Top port noise?
Reply #18 - 03/10/06 at 13:05:49
 
I built an 8" HWK for some "cast off" drivers I had laying around and I used MDF, followed the instructions to the letter, except I flared the ports to start with and it sounded really good as a bedroom sub, very low power use.

Recently, I gave it to a friend who has a lead foot as far as the power goes and there were some resonance issues. I helped him sort it all out, by using Dynamat inside the top and bottom covers, along with incorporating the "BOB JOB" inside the iso chamber.

There was still some panel flex (MDF and partical board are known for ballooning under pressure) and his WAF was not a positive number, so he skinned it with a 1/4" oak face plywood and some trim pieces, thinking it might help the flexion, slightly, but it would balance the WAF equation. Again I helped out and instead of lightly tacking the skin, which he wanted to do quickly to appease her, I used a half a bottle of glue and made it ONE PIECE ... 3/4" MDF + 1/4" plywood. I knew the 1/4" would add some rigidity, but I did not understand how drastically the thin skin would help to stop the flex.

This baby HWK is now solid and sounds very defined and nonresonant. I doubt if the 1/4" material would have the same ability with the larger cab, but you might try some 1/2" glued on well, if panel flex is a problem. It makes it look really nice, too. Grin
Back to top
 
 
  IP Logged
HT-EXT
Ex Member



Re: Top port noise?
Reply #19 - 03/10/06 at 13:17:47
 
Thanks for the reply GEX. The HWK10 used a 4" x 7"(from flare lip to flare lip) but I took two flared ports and made one. The 4" x 8" was only about inch or so away from the speaker magnet(quad loaded). It worked o.k. but the 4" x 7" seem to accept more power and clearence was not an issue. The HWK12 has also workout successfully and it took the standard 4" x 7" without any trouble. The HWK12 likes about 300w+ and has no problem putting out 120db. Just for the record the HWK12 is loaded with KICKER COMPS and it is BADA--! Both HWKs workout great and I am very THANKFUL for all the HELP, INFO, and PATIENCE.      HT-EXT
Back to top
 
 
  IP Logged
Bob
Ex Member



Re: Top port noise?
Reply #20 - 03/10/06 at 13:52:26
 
Thanks Dawg for naming something after me (Assume it's me?) Did you install the mat only on the inside of the 'caps'. Not on the walls?

Thought about an exterior "dressing" (won't call it cosmetics anymore, I got flak over putting makeup on my sub) on it to increase the WAF. Was thinking it may increase the ridgidity also.

Bob
Back to top
 
 
  IP Logged
Adrian D.
Ex Member



Re: Top port noise?
Reply #21 - 03/10/06 at 16:02:05
 
i hate particle board but i actually have all my speakers made out of that stuff  :'(
maybe that's why i ended up hating it.
if i put my phone (even a remote) on the top lid of my db-10 and it gets +150w, the phone vibrates like crazy. ugyl panel flex  :'(
i can actually feel the lid flex when it hits those low-lows.
i'm planning on building one out of 1inch mdf  :-* hoping that flexing will go away.
Back to top
 
 
  IP Logged
Bob
Ex Member



Re: Top port noise?
Reply #22 - 03/10/06 at 17:20:49
 
How about some tasteful exterior bracing?
Bob
Back to top
 
 
  IP Logged
Wreckinthehouse
Ex Member



Re: Top port noise?
Reply #23 - 03/11/06 at 01:26:22
 
Hey Adrian D.,
        I also thought that the top panel was flexing, but upon further inspection, it was actually the whole Housewrecker bouncing around on the floor. Make sure that this is not the case before you go through a lot of trouble. I lay mine sideways when DJing and the problem is solved.
Back to top
 
 
  IP Logged
60ndown
Ex Member



Re: Top port noise?
Reply #24 - 03/13/06 at 14:19:31
 
[quote author=Wreckinthehouse  link=1141303128/15#23 date=1142040382]Hey Adrian D.,

  I also thought that the top panel was flexing, but upon further inspection, it was actually the whole Housewrecker bouncing around on the floor. Make sure that this is not the case before you go through a lot of trouble. I lay mine sideways when DJing and the problem is solved. [/quote]

man, my hwk 15 weighs about 150 lbs, yours bounces around dureing playback?? you mush have some SERIOUS power going to it  ;D Cheesy
Back to top
 
 
  IP Logged
Adrian D.
Ex Member



Re: Top port noise?
Reply #25 - 03/13/06 at 15:18:11
 
no tasteful exterior bracing, because i bought the particle board pre'finished.
no, the box isn't bouncing on the floor. i'm 90% sure it's top lid flex.
i wonder how much that 1 inch mdf wo weighes ??? i wonder how much my 1 inch db-10 will weigh  ???
Back to top
 
 
  IP Logged
Bob
Ex Member



Re: Top port noise?
Reply #26 - 03/13/06 at 16:10:59
 
Close to what you do...

Bob
Back to top
 
 
  IP Logged
Wreckinthehouse
Ex Member



Re: Top port noise?
Reply #27 - 03/14/06 at 23:07:49
 
Hey Adrian,
      Your top and bottom lids are double thick, right?
60NDOWN,
       A Peavey PV-2600 Powers my 2 Housewreckers. 1300 watts per HW.
Back to top
 
 
  IP Logged
Pages: 1 
Send Topic Print