Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Construction Tips Construction techniques and tips

Dynamat inside the box speaker experiences
Dynamat inside the box speaker experiences
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 25th January 2018, 07:19 PM   #1
sbronf is offline sbronf
diyAudio Member
 
Join Date: Nov 2017
Default Dynamat inside the box speaker experiences

Hi to all.
I built two birch plywood speakers. I wanted to ask you if any of you have ever used the dynamat internally, to make the box stiffer. I bought this that is similar to the dynamat ...
https://www.reckhorn.net/pages/damping/abx-alubutyl.php
  Reply With Quote
Old 25th January 2018, 08:42 PM   #2
chrisb is offline chrisb
diyAudio Member
 
Join Date: Aug 2002
Location: victoria BC
I think that Dynamat - and similar products - are mainly intended to dampen resonances of metal surfaces in auto installs. In that regard, I've certainly found them to work very well indeed. Note that the products on Reckhorn site are clearly described for damping in cars (trucks)

As for making a birch plywood box stiffer, it's been my experience that the material is inherently quite stiff- certainly as compared to MDF - but if you think more is required, strategic bracing between panels can help, and needn't be extreme.

Of course the next question raised would be exactly what performance parameter you're looking to optimize by stiffening, and good like finding consensus on priorities, or on the methods / materials to achieve them.
__________________
like my mind, this space intentionally blank
  Reply With Quote
Old 25th January 2018, 09:50 PM   #3
Richidoo is offline Richidoo  United States
diyAudio Member
 
Join Date: Oct 2005
Location: Raleigh
Dynamat and yours have an aluminum layer for reflecting heat in automotive applications. 2mm thickness works on 18ga steel with very high resonant freq, but not enough mass for damping heavier and lower resonant frequency birch. It's also very expensive because of the automotive specialty.

I use roofing membrane. 5mm thick, 1lb/sq ft/$1.
  Reply With Quote
Old 28th January 2018, 08:34 PM   #4
stephenmarklay is offline stephenmarklay  United States
diyAudio Member
 
Join Date: Nov 2009
Just a quick thought. By adding roofing material or Dynamat (in layers) you are not adding stiffness. You are adding mass without stiffness and that is the idea. Thin Plywood works well since it is stiff for it’s thickness but not so stiff (like 3/4”) that the resonance is up in the midrange where it can be heard easily.

The extra mass does not change the frequency but it will smear them out and lower the amplitude. Lowering the amplitude is what you are doing and why it works.

As above you can add multiple layers of Dynamat or similar. Or use few layers of thicker material. I have used RAAM mat since I had a lot of it. It works fine in layers. I would suggest 3-4 layers depending on the size of the box. On a bookshelf size I used 3 layers on the sides on a two on the very small top and bottom.
  Reply With Quote
Old 29th January 2018, 06:46 AM   #5
sbronf is offline sbronf
diyAudio Member
 
Join Date: Nov 2017
Here an interesting article about the importance of bracing and stiffness
Thanks
Myths & Facts about Loudspeaker Cabinets: Identifying Legitimately High Fidelity Designs | Audioholics
  Reply With Quote
Old 13th February 2018, 10:56 AM   #6
sbronf is offline sbronf
diyAudio Member
 
Join Date: Nov 2017
Hi, I wanted to tell you my experience on the sound-absorbing material.
in a closed box I replaced the polyester I had previously used, with pure carded wool with long fibers.
The change has been remarkable, now the box no longer booms, as if it were full, with the use of only 50 grams of wool for each cabinet.
  Reply With Quote
Old 15th February 2018, 02:14 AM   #7
stephenmarklay is offline stephenmarklay  United States
diyAudio Member
 
Join Date: Nov 2009
Quote:
Originally Posted by sbronf View Post
Here an interesting article about the importance of bracing and stiffness
Thanks
Myths & Facts about Loudspeaker Cabinets: Identifying Legitimately High Fidelity Designs | Audioholics
I donít agree with everything said about cabinets in this article. This is contrary to the BBC engineers and it is also country to Kef engineers that developed the LS50.
  Reply With Quote
Old 15th February 2018, 09:32 PM   #8
chrisb is offline chrisb
diyAudio Member
 
Join Date: Aug 2002
Location: victoria BC
Ah yes, the search for consensus on any aspect of loudspeaker enclosure design is, I think, a fool's errand.
__________________
like my mind, this space intentionally blank
  Reply With Quote

Reply


Dynamat inside the box speaker experiencesHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
WOOD experiences in Bamboo speaker building. Reeler Parts 4 13th December 2014 06:01 PM
Building a 4-way speaker: some experiences M4rtin Multi-Way 28 25th July 2014 07:50 PM
dynamat for lining inside cabs slr 5000 Multi-Way 2 14th October 2008 11:32 PM
Dynamat on speaker spider kazoo Full Range 6 9th March 2005 12:48 PM


New To Site? Need Help?

All times are GMT. The time now is 12:16 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki