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Air flow in ported box
Suppose you had a tall thin box with a port at the bottom. A naive take on it would be that vertical bracing would be "along" the direction of air flow, and horizontal bracing would "disrupt" the air flow. But in reality, is there any difference? And if so, which is better?
Scratching my head.
Comments
Just put the matrix bracing on the out side .
CHeers
Oh, that is gold Mal, gold I tells ya!
Agree!
Think of all the extra shelving space for knick knacks!
hey john, think of the wavelengths involved at the port tuning frequency!
At 5 or so metres long, I cant imagine shelves make a single lick of difference!
Hm... not sure about that... after all the port is only 30cm long and it makes a difference...
Suppose you had a shelf brace across the enclosure, with a few 3mm holes drilled in it. That would make a difference, right? Make the holes bigger, a different difference. Keep making them bigger, somewhere along the way the difference stops being different. I'm supposing though that any reasonable fraction drilled out (> 20%? 50%?) would be past that point.
In the end, I designed the box so that the braces are "along" the box. Pics latr (unless it starts raining which it feels like it might...)
Hi Mal, I love the look, it reminds of the machine in The Fly! I've thought of trying it with arced bracing, e.g. thicker in the center of the cabinet. Finishing it would be hard though.
Reminds me of a catylst decomposer at work :-) .
Or the design of the PSE144 bass cab's I'm looking at building
CHeers
Cool. Laminated again?
Not this time ,there's a budget .
Oh you're doing the bracing on the outside on that one? Sorry I'm now confused
No now I'm confused .
Oh good, that makes three of us!
I'm not sure if this will come through very well, but here's the cross-section of what I ended up with for this (the ported base for mini convertible):
Ummm let's try again:
The green ones are vertical braces. I was thinking about having a lot more horizontal ones instead.
Nice :-)
Any brace in a speaker can act as a helmholz resonator and start to mess up the frequency response. Yes, it matters! You have to be careful that your box bracing does not resemble a helmholz resonator. In a sub box you don't worry - it's all about stiffness. In a full range box above 100 Hz you start to think a lot more about damping of box vibrations, which I consider more important than bracing.
Hi Paul, what would you use to (cheaply) damp vibrations?
Hmm..... I'm wondering if I've created a problem. This is the cross-section when the base and monitor are bolted together:
This is the detail view of the join area:
The size of the two openings are 69x90 and 41x90. Thing is, they are 54mm length.... have I inadvertently created a "double bass reflex" enclosure...? I'm wondering how I can figure out what effect this will have (before building it) - any suggestions?
OK, here's a revised version that will I hope avoid any potential issues.