Hi there,
I'm in the middle of building this thing. Now I'm thinking about the bracing of wings.
Attached drawing is the idea. The lower half is what it looks like when looking into the aperture as the arrow in the upper half. And it's flipped to let the aperture facing down.
On the left, there're several triangles connecting side wall and the wing. This is simple.
On the right, it's a solid block. I'm not quite sure what material would be ideal for this. (PU foam?)
Question is, how do they affect the sound? By the method on the left, would there be 'tubulance' or the like to act like a low pass filter? OTOH, is there any benefit to do the solid block on the right?
I'm in the middle of building this thing. Now I'm thinking about the bracing of wings.
Attached drawing is the idea. The lower half is what it looks like when looking into the aperture as the arrow in the upper half. And it's flipped to let the aperture facing down.
On the left, there're several triangles connecting side wall and the wing. This is simple.
On the right, it's a solid block. I'm not quite sure what material would be ideal for this. (PU foam?)
Question is, how do they affect the sound? By the method on the left, would there be 'tubulance' or the like to act like a low pass filter? OTOH, is there any benefit to do the solid block on the right?
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The big block will have less reflections and give you a smoother response. It also has the advantage of reducing the chamber volume which increases the upper frequency bandwidth. A good thing. It is stiffer and sturdier than individual little brace panels. You can do it with the little braces for strength, test it, then add a big shaped foam block with wood ribs as extra bracing.
That's a great idea! I have no idea what it would sound like, but I can give you an idea of relative frequencies and mode shapes.
I ran a quick modal on that to see what the difference would be. I just took my model for the 0.4x Karlsonator and modified it. Then I fixed the whole enclosure (not allowing the enclosure to move) except the aperture to isolate it's modes. I have very little time today to run this, but I wanted to post some quick results since this is a cool idea. In the first image the green things indicate fixed surfaces, I hid them for the others.
Here's the model with no bracing. First mode at 221 Hz.
Then I added a single triangle brace at the point of highest deflection. If I had more time to optimize I'd try up to 3, maybe later. The triangle ends are at 0.25" away from the aperture edge and the speaker baffle. First mode comes up to 370 Hz. Very nice improvement.
Then I made the "Block" version, except I made it with just a sheet, as if it were like the rest of the panel material. I figured this would be a nicely conservative result. And by looking at the plot I was right. The new brace is what's causing the first mode and it's up at 487 Hz! I moved the view a little to show the brace inside moving. Again, it's 0.25" away from the edges on all three corners.
That corner one seems like the best option as far as first mode goes. And if XRK thinks it will improve the performance with the front chamber volume modification, I don't see how you can't lose!
If you would like me to go further, let me know what you'd like to see and I'll try to model it on Monday.
XRK, would there be any benefit to doing something like the corner block in the 0.4x Karlsonator? Or maybe any of your other K-aperture designs?
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Mudjester,
On the Karlsonator we rely on the front chamber volume to extend the bass a bit so not sure how it would all play out. This may change the function of the K aperture as an acoustic lens for HF diffraction which is how the polar response is very uniform. Worth a try in foam core of not anything else. For the Kazba sub though we are dealing with lower frequencies - I wasn't sure where CLS is intending to XO. If below 700Hz I think the block will work well. Nice modeling result there - thanks!
On the Karlsonator we rely on the front chamber volume to extend the bass a bit so not sure how it would all play out. This may change the function of the K aperture as an acoustic lens for HF diffraction which is how the polar response is very uniform. Worth a try in foam core of not anything else. For the Kazba sub though we are dealing with lower frequencies - I wasn't sure where CLS is intending to XO. If below 700Hz I think the block will work well. Nice modeling result there - thanks!
Happy to help advance the designs. Let me know if there's anything else I can do that would be helpful.
Maybe for the purposes of the Kazba I should look into how to get the first mode above 700 Hz? CLS, what material are you using? I think I can get data for most foams and woods that would allow me to get ballpark mode frequencies.
I'll put other Karlsonator stuff in the other thread.
And it looks like he's planning on a 18 inch woofer. That would be hard to get up to 700, but I would be surprise if the plan was to cross that high. CLS, if you'd like some modal sims of the aperture, let me know what you're going to use and how big it will be and I'll optimize the design best I can.
18mm thick, yes. But sadly, BB ply is not available here. I use pine board to save effort in cutting and finish. It's very light and soft.
If I go solution of block, it'll be after I have attached 4 triangles along a 90 cm length. The block will probably be some kind of PU foam. It seems there're many types with different hardness.
If I go solution of block, it'll be after I have attached 4 triangles along a 90 cm length. The block will probably be some kind of PU foam. It seems there're many types with different hardness.
Hi,
Please see the CAD drawing as attached. The slant of the baffle is 20 degree.
2 separate wings for each K-aperture. And each wing will be secured to a side plate and top plate first, then this assembly is fitted onto the whole H-frame. In this way, I can do experiments to the bracing/damping of wings etc.
All material is 18 mm thick pine board. (Or maybe I'll add some more little triangles of 15 mm plywood. I got some leftover.)
Please see the CAD drawing as attached. The slant of the baffle is 20 degree.
2 separate wings for each K-aperture. And each wing will be secured to a side plate and top plate first, then this assembly is fitted onto the whole H-frame. In this way, I can do experiments to the bracing/damping of wings etc.
All material is 18 mm thick pine board. (Or maybe I'll add some more little triangles of 15 mm plywood. I got some leftover.)
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I'm pretty sure it will work.
At least, I'll have an Z-baffle OB with even order distortion cancellation and slot loaded bandpass effect brought by the K-slot. No matter how high it can go, I can use it anyway.
Its bandwidth will never be narrower than the push-pull slot loaded OB I'm using now.
The magic of Karlson is what I'm looking forward to.
At least, I'll have an Z-baffle OB with even order distortion cancellation and slot loaded bandpass effect brought by the K-slot. No matter how high it can go, I can use it anyway.
Its bandwidth will never be narrower than the push-pull slot loaded OB I'm using now. The magic of Karlson is what I'm looking forward to.
Nice drawing. All the detail I need.
I've made up a model, attached is an image of the model of the aperture assembly minus the H-frame. I took out the curves you added in the sides to make it easier not to exceed the height of the sides with the braces. I can add those back in later when the design is more mature, but I don't think it will matter much.
Now all I need is to find the material properties of Pine. So far I'm noticing that there are lots of different kinds of Pine. Any idea which kind you're using?
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