Ron E said:
That looks like it is a good reference -- i'll comment more once i have a chance to properly read it -- a couple quick comments.
I see he experimentally validates the longitudanal brace, and that there is an indication that a brace should reach across to th eopposite panel.
With respect to Jim Moriyasu from AudioExpress (Feb. 2002) entitled, Panel Damping Studies: Reducing Loudspeaker Enclosure Vibrations, this has somewhat limited application as he made the classic error of placing the praces exactly in the middle of the panels. I chatted with him about this, and he said he didn't see himself getting around to exploring the subject further.
dave
Most of what you need for practical examples is probably here.
http://www.exdreamaudio.de/Boxen-Baumaterial/boxen-baumaterial.html
Thorsten posted a quick summery of what the page says for those (like me) who can't read German.
Hope that gives some info for your wiki. Since it is from that website you had better contact them about permissions though.
http://www.exdreamaudio.de/Boxen-Baumaterial/boxen-baumaterial.html
Thorsten posted a quick summery of what the page says for those (like me) who can't read German.
Hope that gives some info for your wiki. Since it is from that website you had better contact them about permissions though.
Circles.
I've just looked through this thread and am amazed to find no mention of the seminal Stephens JAES paper. For maximum rigidity, you position your brace so as to minimise the diameter of circles that can be inscribed. That means that a rectangular panel should have a brace running centrally along the long dimension, rather than diagonally or across the width. It's why transmission line loudspeakers work well - their dividers inevitably end up in this orientation. To work well, a brace needs to be a panel going all the way to the opposite wall. To prevent it turning into a transmission line, it needs large holes in it. Now you know where B&W's "Matrix" idea comes from.
I've just looked through this thread and am amazed to find no mention of the seminal Stephens JAES paper. For maximum rigidity, you position your brace so as to minimise the diameter of circles that can be inscribed. That means that a rectangular panel should have a brace running centrally along the long dimension, rather than diagonally or across the width. It's why transmission line loudspeakers work well - their dividers inevitably end up in this orientation. To work well, a brace needs to be a panel going all the way to the opposite wall. To prevent it turning into a transmission line, it needs large holes in it. Now you know where B&W's "Matrix" idea comes from.
More time tonight....
Perhaps a semantic issue, but the goal of bracing is to reduce cabinet talk, the practical result is to increase resonant frequency and/or increase damping rate. This is perhaps more generally true of cabinet construction rather than simply bracing.
Good observation. Perhaps true both for acoustic and structural vibration.
I mostly agree with this, bracing is certainly more economical on material. I have never been of the thick wall camp.
I'll look at this and the other resonance question later....
Can't argue with that.
This doesn't make sense (perhaps you were too brief) and the dimensions in mm are incorrect conversions.
While it is true that trangles make stiff structures, make sure that you clarify that diagonal panel braces are ineffective. The advice for triangular bracing structures should be considered advice as to what the cutouts in braces should look like (i.e. trusses make very stiff, light structures). Square cutouts will "shear" easier.
I agree with most of this. Bracing magnets to the box, I am a little iffy on. Seems like a recipe for rattle/buzz.
Note that Weems in his ancient and deceptively simplistic books recommends a longitudinal rib just off center.
I think you mean 3/4" side attached to box, not "deeper side".
Metal braces I agree with, but steel rods as point braces are not likely to be effective.
Doubting that stressing the panels will have a beneficial effect. MDF and particle board especially and all materials to some extent will creep, or relax under stress. What was once tight, might end up loose and rattle. Whether rods are good or not depends on implementation.
Needs development.
This confuses acoustic with panel resonances. Subwoofers are just as important to brace, but bracing only needs to put the resonances out of band.
~16 years ago, a friend made a 10 cubic foot box (I think it was golden ratio-my first box design) out of 3/4 ply with one shelf cutting it into two 5 cube boxes. That thing vibrated a LOT even though it was limited to below 80Hz. 2x PYLE 12" drivers. Sure was loud, and no rattles
, except the furniture and the drywall, and the cupboards upstairs, etc.... ahh, the folly of youth. 120dB at 15 feet with a 80 watt onkyo receiver.....
rick57 said:
Perhaps a semantic issue, but the goal of bracing is to reduce cabinet talk, the practical result is to increase resonant frequency and/or increase damping rate. This is perhaps more generally true of cabinet construction rather than simply bracing.
rick57 said:
Good observation. Perhaps true both for acoustic and structural vibration.
I mostly agree with this, bracing is certainly more economical on material. I have never been of the thick wall camp.
I'll look at this and the other resonance question later....
Can't argue with that.
This doesn't make sense (perhaps you were too brief) and the dimensions in mm are incorrect conversions.
While it is true that trangles make stiff structures, make sure that you clarify that diagonal panel braces are ineffective. The advice for triangular bracing structures should be considered advice as to what the cutouts in braces should look like (i.e. trusses make very stiff, light structures). Square cutouts will "shear" easier.
I agree with most of this. Bracing magnets to the box, I am a little iffy on. Seems like a recipe for rattle/buzz.
Note that Weems in his ancient and deceptively simplistic books recommends a longitudinal rib just off center.
I think you mean 3/4" side attached to box, not "deeper side".
Metal braces I agree with, but steel rods as point braces are not likely to be effective.
Doubting that stressing the panels will have a beneficial effect. MDF and particle board especially and all materials to some extent will creep, or relax under stress. What was once tight, might end up loose and rattle. Whether rods are good or not depends on implementation.
Needs development.
This confuses acoustic with panel resonances. Subwoofers are just as important to brace, but bracing only needs to put the resonances out of band.
~16 years ago, a friend made a 10 cubic foot box (I think it was golden ratio-my first box design) out of 3/4 ply with one shelf cutting it into two 5 cube boxes. That thing vibrated a LOT even though it was limited to below 80Hz. 2x PYLE 12" drivers. Sure was loud, and no rattles
, except the furniture and the drywall, and the cupboards upstairs, etc.... ahh, the folly of youth. 120dB at 15 feet with a 80 watt onkyo receiver.....
Re: Re: Re: Wiki on bracing
Perhaps a (where am I standing) deal, but the way I look at it you are focused on the brace when perhaps you should be focused on the cabinet.
What we want is a cabinet that doesn't talk.
Our options:
-Try different materials: heavy light, stiff, floppy,lossy, resonant....
-Use different shapes - e.g. sonotubes have inherent advantages/disadvantages
-Use braces and/or ribs
-composite panel construction methods.
-any or all of the above
planet10 said:
Perhaps a (where am I standing) deal, but the way I look at it you are focused on the brace when perhaps you should be focused on the cabinet.
What we want is a cabinet that doesn't talk.
Our options:
-Try different materials: heavy light, stiff, floppy,lossy, resonant....
-Use different shapes - e.g. sonotubes have inherent advantages/disadvantages
-Use braces and/or ribs
-composite panel construction methods.
-any or all of the above
My apologies, I fess up, I need a rap on the knuckles for my inability to comprehend the How to create & edit wiki pages www.diyaudio.com/wiki/index.php?page=How+to+create+&+edit+wiki+pages which is just now v 1 of the Wiki on bracing . . 
if need be, I have the original text on my hard disc.
I plead for leniency in that I thought I’d jump in, thinking I’d hopefully do more good than harm.
Maybe there should be a point “creating a wiki from prepared text”, or how to create “new wiki pages for dummies”
On the content, thanks for the further material, I haven’t time to look it at properly yet, but that Thorsten via Tenson material looks good, the sooner the wiki is going in the right place, the better.
if need be, I have the original text on my hard disc.
I plead for leniency in that I thought I’d jump in, thinking I’d hopefully do more good than harm.
Maybe there should be a point “creating a wiki from prepared text”, or how to create “new wiki pages for dummies”
On the content, thanks for the further material, I haven’t time to look it at properly yet, but that Thorsten via Tenson material looks good, the sooner the wiki is going in the right place, the better.
a quick one
It’s good to put things in perspective, but my intention was this thread ~ wiki will just be on bracing.
It’d be good to later expand or perhaps more likely link it to include Ron E’s suggestion of cabinet construction, and CeramicMan’s suggestion of loudspeaker design techniques.
Also I agree with dave’s suggestion that there be different schools of thought stated.
I thought lets get one school or page completish first. How do I paste it into a new wiki?
Thanks
It’s good to put things in perspective, but my intention was this thread ~ wiki will just be on bracing.
It’d be good to later expand or perhaps more likely link it to include Ron E’s suggestion of cabinet construction, and CeramicMan’s suggestion of loudspeaker design techniques.
Also I agree with dave’s suggestion that there be different schools of thought stated.
I thought lets get one school or page completish first. How do I paste it into a new wiki?
Thanks
Re: a quick one
Rick,
I’m not at all an expert but I suggest you give it a try by reading these links first and try something in the sandbox.
http://www.diyaudio.com/wiki/index.php?page=SandBox
http://www.diyaudio.com/wiki/index.php?page=FormattingRules
Great idea BTW.
/Hugo
rick57 said:
I thought lets get one school or page completish first. How do I paste it into a new wiki?
Rick,
I’m not at all an expert but I suggest you give it a try by reading these links first and try something in the sandbox.
http://www.diyaudio.com/wiki/index.php?page=SandBox
http://www.diyaudio.com/wiki/index.php?page=FormattingRules
Great idea BTW.
/Hugo
If it works like other wikis all you do is create a link to the new page on an existing page. The wiki auto creates an empty page which you then navigate to and edit.
I created it in about 30 seconds despite never having created a wiki page before. Computer tip: look at something already created and copy it. That's what I did.
Here it is: http://www.diyaudio.com/wiki/index.php?page=Cabinet+Bracing
It's linked off the Loudspeaker wiki page in the "Articles" section. I'll let rick57 add his own text.
I created it in about 30 seconds despite never having created a wiki page before. Computer tip: look at something already created and copy it. That's what I did.
Here it is: http://www.diyaudio.com/wiki/index.php?page=Cabinet+Bracing
It's linked off the Loudspeaker wiki page in the "Articles" section. I'll let rick57 add his own text.
the wiki is there. 
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