Any experience in designing a Helmholtz bass trap? - diyAudio
Go Back   Home > Forums > General Interest > Everything Else

Everything Else Anything related to audio / video / electronics etc) BUT remember- we have many new forums where your thread may now fit! .... Parts, Equipment & Tools, Construction Tips, Software Tools......

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 5th July 2002, 05:17 AM   #1
diyAudio Member
 
Join Date: Jul 2002
Location: Venezuela
Default Any experience in designing a Helmholtz bass trap?

Hi.
I´ve been reading and researching everywhere and realized Helmholtz bass traps are intended to absorbing a narrow band of freqs.

Can anyone give me some cook-receipt on tuning a cylinder to kill a 72 Hz ringing I couldn´t get rid of with my wall panels?

Thanks a lot.
Marcelo.
  Reply With Quote
Old 5th July 2002, 05:35 AM   #2
diyAudio Member
 
Bill Fitzpatrick's Avatar
 
Join Date: Jun 2001
Location: Eugene, OR
Can you supply more details. The term "ringing" applies to high Q systems. Perhaps you simply have a standing wave problem.
  Reply With Quote
Old 5th July 2002, 05:43 AM   #3
diyAudio Member
 
Join Date: Jul 2002
Location: Venezuela
Thumbs up Of course!

Thank you, Bill

Yes, you´re right. What I´m trying to kill is a SW that corresponds to the vertical first mode (about 7,5 ft from floor to ceiling). My DIY back-wall (air tight) wood panels perform very well and helped minimize 135 and 90 Hz SW my room had. But they failed below that freqs.
So I´m thinking about a tuned cylinder, I mean a Helmholtz resonator at 70 Hz or so.

I couldn´t find other that theoretic physics on that devices. Nothing to put hand on, I mean.

Any comment welcome.

Cheers.
Marcelo.
  Reply With Quote
Old 5th July 2002, 06:23 AM   #4
diyAudio Member
 
Bill Fitzpatrick's Avatar
 
Join Date: Jun 2001
Location: Eugene, OR
I guess we can assume that your speakers themselves are not responsible for excessive, high Q output at 72Hz?

I'll admit that I am somewhat surprised. Floor to ceiling standing waves are usually much less of a problem at the listening position than front to back standing waves. You didn't offer complete room dimensions so I can't be sure but you may have a tangential 72Hz mode that is adding to the problem. You may also have some peaking at that frequency due to room reflections. Often, moving the speakers as little as a few inches can solve these problems.

Before you start adding more devices in your room, I would suggest that, if practical, raising or lowering the driver that is responsible for reproducing 72Hz might offer a solution. You could always tilt the speaker to get back on axis.

You might be interested in our program, Visual Ears, which addresses these very problems and the use of which often removes the need for room treatment altogether. We have lots of completely satisfied users.

Full details can be found at www.kbacoustics.com

There is some useful information on Helmholtz resonators in the "Master Handbook of Acoustics" that you might want to refer to.

Hope this helps.
  Reply With Quote
Old 5th July 2002, 07:33 AM   #5
ergo is offline ergo  Estonia
diyAudio Member
 
Join Date: Mar 2001
Location: Tallinn, Estonia
ETF 5 has the ability to calculate helmholz bass traps. I think it works in demo version also.

http://www.etfacoustic.com/

Ergo
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
1 giant subwoofer + bass trap or 2 smaller ones? santiu Subwoofers 3 28th December 2007 04:47 AM
Passive radiator use in bass trap? roland bios Multi-Way 16 29th December 2006 02:24 AM
Helmholtz bass absorber, where to place? banana Multi-Way 3 26th July 2006 04:13 PM
A new type of bass trap/diffuser room treatment?(long) darkmoebius Everything Else 3 28th November 2005 11:39 AM


New To Site? Need Help?

All times are GMT. The time now is 06:26 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2