Do these braces need improvement

ShinOBIWAN

diyAudio Member
2004-02-25 9:13 pm
UK
Plenty of bracing there.

The only thing I'd redo and I'm picky, would be the center brace on the bass cabinet. All of the two braces that connect front to back are only joined by a small amount of MDF because of the circle cuts in the adjoining brace.

It will be fine without but I'd redo the top to bottom brace with squares inside of circles to allow full contact on the other braces - OTT maybe but if a job is worth doing its worth doing right.
 

andy2

Member
2004-11-17 4:46 pm
ShinOBIWAN said:
Plenty of bracing there.

The only thing I'd redo and I'm picky, would be the center brace on the bass cabinet. All of the two braces that connect front to back are only joined by a small amount of MDF because of the circle cuts in the adjoining brace.

It will be fine without but I'd redo the top to bottom brace with squares inside of circles to allow full contact on the other braces - OTT maybe but if a job is worth doing its worth doing right.


I understand what you mean but I already ran out of wood and to do that I need to purchase another 4 x 8' panel. What I'll do is glue a small piece of wood at the opening in between those braces (that you mention) so that they are pushed against each other which would give them extra strength. Not perfect but a little bit better.
 
Originally posted by andy2



Where is the most effective place for it then?


Off centre, prefereably at an angle... in the middle of a panel, the brace actually does little to suppress the 1st resonance of that panel -- it can actually enhance it (ie make it worse).

You should also make sure that the cross-braces are not symetrically placed as well, and that they don't brace to create a square sub panel.

dave
 
Originally posted by BassAwdyO
with the brace in the middle shouldnt it control the 1st resonance, but not the 2nd, 4th, 6th and other even multiples?


Any waveform that has a null in the middle of the panel will have a minimum amount of suppression. Because the wall is clamped at this null point, energy at similar frequencies can feed these resonances as well, giving a situation where the panel can actually be worse after bracing.

dave
 

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Originally posted by andy2
Would it better to have two main braces -- one would be at 1/3 the length of the box?


Within reason more braces are better. Think irrational numbers/ratios when you are planning placement and if they can be at an angle even better (ie divides panels into trregular trapezoids instead of rectangles.

dave
 

SpeakerBob

Member
2002-08-15 6:21 pm
UK
Dave,

How does the 'matrix' style bracing work out in a midrange enclosure? - ie braced squarely, every 4" or so front to back, side to side and top to bottom. Would this push any resonances up above the mids bandwidth ? 4.5" is 3000Hz.

I've been reading a bit on bracing recently, and some stuff seems to counteract the other so to speak. ie adding bitumen to panels lowers resonance / bracing raises. I also read somewhere to brace to raise the resonance and to add bitumen to kill whats left. Also can we not add stuffing to kill the 3000Hz before it hits the walls so to speak ?

Hope this isn't threadjacking btw - Can move it to a new thread if you like.:)

Cheers,

Rob
 
Originally posted by RobWells
How does the 'matrix' style bracing work out in a midrange enclosure? - ie braced squarely, every 4" or so front to back, side to side and top to bottom. Would this push any resonances up above the mids bandwidth ? 4.5" is 3000Hz.


At that spacing little is going to move, but equal spacing is probably a compromise.

I've been reading a bit on bracing recently, and some stuff seems to counteract the other so to speak. ie adding bitumen to panels lowers resonance / bracing raises. I also read somewhere to brace to raise the resonance and to add bitumen to kill whats left. Also can we not add stuffing to kill the 3000Hz before it hits the walls so to speak ?


At 3k not a lot of energy is going to hit the walls. Bitimen is not something i like to use. Stores energy & lowers panel resonance.

dave