Bracing material? - Page 11 - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

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 17th November 2012, 11:59 AM   #101
diyAudio Member
 
JRKO's Avatar
 
Join Date: Dec 2003
Location: U.K.
Send a message via AIM to JRKO
Quote:
Originally Posted by Baseballbat View Post
What is sufficient energy?
You should be telling us. You are telling us in no uncertain terms it can & will happen. How can we hope to cure the problem you say always exists unless you know how to start the problem off?

Heres how: You need sufficient volume, a badly designed & built cabinet and maybe a disc of test tones.

All of which are easily remidied by 1) not playing at 100db (85db to keep your hearing ), 2) don't be a wally when designing & building your cabinet and 3) listen to music not test tones

In other words: Its not an issue in a large percentage of cases in the real world. (There are always exceptions to the rule)
__________________
If I'm not making noise, I'm making something to make noise
  Reply With Quote
Old 17th November 2012, 01:42 PM   #102
diyAudio Member
 
Join Date: Apr 2007
Quote:
Originally Posted by JRKO View Post
Do you have practical experience in this field?
Maybe you should take a quick look at this post: Is enclousure strengthening needed?

Quote:
You ignore the fact that normal people listen to music not test tones/sweeps
What are the differences between test tones and music?

Quote:
What about that is wrong?
Everything?
  Reply With Quote
Old 17th November 2012, 03:41 PM   #103
diyAudio Member
 
Join Date: Feb 2010
Location: in half space
Quote:
Originally Posted by Baseballbat View Post
Wrong. No matter how much energy you put into it, the resonance is always there. And, at resonance, the panel is more likely to receive the energy, because both impedances, mass and stiffness, cancel out and there's only the resistance (the damping) working.
The impedances cancel out?

Consider a lead ball hanging on a string. It will have inertia due to its mass, and to move the ball we need enough force to overcome the inertia. Now, replace the string with a steel wire, fixed rather than hinged at both ends. The wire will act as a spring, and the spring will add to the inertia of the ball, thus even more force will be required. Increase the stiffness of the wire, and the force requirement will increase further. At no point does the stiffness 'cancel out' the inertia of the mass.
  Reply With Quote
Old 17th November 2012, 03:56 PM   #104
diyAudio Member
 
Join Date: Apr 2007
What is the complex impedance of ANY resonant circuit (regardless if electrical, mechanical or acoustical) at resonance? The phase is zero, so the complex impedance is purely resistive. The impedances of mass and stiffness (or inductance and capacitance) cancel out, and only the damping resistive part works.

Come on, that are basics!
  Reply With Quote
Old 17th November 2012, 04:09 PM   #105
diyAudio Member
 
mondogenerator's Avatar
 
Join Date: Sep 2009
Location: City Of Villans
Blog Entries: 1
Quote:
Originally Posted by Baseballbat View Post
What is the complex impedance of ANY resonant circuit (regardless if electrical, mechanical or acoustical) at resonance? The phase is zero, so the complex impedance is purely resistive. The impedances of mass and stiffness (or inductance and capacitance) cancel out, and only the damping resistive part works.

Come on, that are basics!
A resonant system as i understand it, is at its simplest a 2nd order transfer function M-C-K system of mass M, damper C ,and compliance K. Much akin to a car suspension system. I must say that i thought the phase was 180deg not 0, but ive been wrong many times.

You are correct, just like in a parallel LC at resonance Xc and Xl cancel leaving R, resistive loss.

The real question is what level of loss is optimal, how to achieve it in a given panel in order to coincide with the resonance, and damp it optimally.

At all other frequencies, our attentions can then be turned to reflective and diffractive absorption.
__________________
Every new piece of knowledge pushes something else out of my brain - Homer.....................Simpson

Last edited by mondogenerator; 17th November 2012 at 04:15 PM.
  Reply With Quote
Old 17th November 2012, 04:34 PM   #106
diyAudio Member
 
JRKO's Avatar
 
Join Date: Dec 2003
Location: U.K.
Send a message via AIM to JRKO
Quote:
Originally Posted by Baseballbat View Post
Maybe you should take a quick look at this post: Is enclousure strengthening needed?
I see math not music. Can you hear it? Or can you only measure it?

I've said it before, I'll say it again. Music has been around since someone could repeatedly grunt at the same pitch. It exists now away from hifi and will continue to survive without hifi. The same cannot be said of hifi.

Quote:
What are the differences between test tones and music?
um let me see, Mozart, Sandy Denny, Joe Bonamassa etc etc? I could go on but I don't know if you'll get my drift (where can I buy test tones 5th or greatest hits?)

Quote:
Originally Posted by Baseballbat View Post
Come on, that are basics!
But then so is listening to actual music on your stereo and being content, instead of using an a accelerometer to measure something you in all probability cant hear
__________________
If I'm not making noise, I'm making something to make noise
  Reply With Quote
Old 17th November 2012, 04:42 PM   #107
diyAudio Member
 
Join Date: Apr 2007
Quote:
Originally Posted by JRKO View Post
I see math not music.
Then you should probably do not post on this topic...

Quote:
um let me see, Mozart, Sandy Denny, Joe Bonamassa etc etc?
That's no difference. You know, I could use Mozart instead of test tones. It doesn't matter, I can still measure the resonances. That's signal theory.

Quote:
But then so is listening to actual music on your stereo and being content, instead of using an a accelerometer to measure something you in all probability cant hear
You were talking about excitation of panel resonances. Audibility is another topic, and should be discussed separately.
  Reply With Quote
Old 17th November 2012, 05:02 PM   #108
Mooly is online now Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007


This is a warning to keep this thread civil. I've pulled a couple of posts... anymore will see points issued
__________________
-------------------------------------------------------
Installing and using LTspice. From beginner to advanced.
  Reply With Quote
Old 17th November 2012, 05:17 PM   #109
diyAudio Member
 
Join Date: Feb 2010
Location: in half space
Quote:
Originally Posted by Baseballbat View Post
What is the complex impedance of ANY resonant circuit (regardless if electrical, mechanical or acoustical) at resonance? The phase is zero, so the complex impedance is purely resistive. The impedances of mass and stiffness (or inductance and capacitance) cancel out, and only the damping resistive part works.
The "impedances" can't cancel out, because neither is a simple number. This isn't electronics or theoretical physics. There will be a resonance at some frequency, as Dave specified, but you seem to be arguing the "purely resistive" part is negligible.


Dave said:
Quote:
Originally Posted by planet10 View Post
Fighting this is the natural energy dissipation of the material which is related to the relative dimensional differences between the material thickness and the wavelength in question.
To which you replied, "What?" The question hasn't been answered, but it would behoove you to figure out to what he was referring.


BTW. The measurements you posted ( Is enclousure strengthening needed? ) merely show that what you refer to as "heavily braced"... isn't.
  Reply With Quote
Old 17th November 2012, 05:27 PM   #110
diyAudio Member
 
Join Date: Apr 2007
Quote:
Originally Posted by Keriwena View Post
The "impedances" can't cancel out, because neither is a simple number. This isn't electronics or theoretical physics.
Yes, it is. And you should really take a lesson in it.

The "natural energy dissipation" is the resisitve part in the complex impedance, so at resonance only this works. But there is (nearly) nothing non-linear in the damping over a wide range of stress and strain, so every resonance is excited during playback of music even at low levels.
  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
Bracing Howard Subwoofers 3 28th March 2012 02:55 PM
Transformer potting material? what material? rvrazvan Tubes / Valves 38 10th October 2011 06:02 PM
How much bracing is necessary? Frosteh Subwoofers 91 28th September 2011 12:59 AM
Enough bracing? Vikash Multi-Way 51 8th May 2006 06:58 PM
how much bracing is enough gwgjr31 Subwoofers 1 5th May 2006 07:57 AM


New To Site? Need Help?

All times are GMT. The time now is 08:06 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