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MultiWay Conventional loudspeakers with crossovers 

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6th October 2018, 10:24 PM  #21 
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Join Date: Apr 2018

Call me mathematically challenged, but I don't understand that lens volume calculator!
Last edited by Galu; 6th October 2018 at 10:42 PM. 
6th October 2018, 10:34 PM  #22 
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Join Date: Apr 2018

Last edited by Galu; 6th October 2018 at 10:37 PM. 
7th October 2018, 12:41 AM  #23  
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Join Date: Jul 2003
Location: Doerun, GA

Quote:
That lens calculator describes a biconvex lens with a cylindrical middle section between the two convex surfaces. r_{1}  describes the radius of curvature for the (spherical) convex surface on the left r_{2}  describes the radius of curvature for the (spherical) convex surface on the right r_{c}  describes the radius of the cylinder that intersects the two convex surfaces h_{c}  describes the length of the cylinder between the two convex surfaces In the case of the OP, we want the volume under one spherical convex surface cut off by a plane. The plane intersects as a circle with whatever radius the OP wants as his opening. As an example, let's use a 14" diameter sphere with an 8" speaker. Ignore baffle size, kerf, etc for the sake of demonstration and assume we want a hole with an 8" diameter. So we want the intersection in our case to be flat circle, a cylinder with a height of 0 and diameter of the speaker. This gives us: h_{c} = 0, and r_{c} = 4 Using the left convex side as our spherical cap to be removed, which is being cut off the 14" sphere, giving us: r_{1} = 7 We want the right surface to be flat, not convex. So the radius of the right side should be infinity, or high enough to be of little consequence. Let's use: r_{2} = 10000 Inserting these values into Richidoo's link gives us 32.609 for the volume of the spherical cap to be removed from the OP's sphere. In Galu's link, using r=7 and chord = 8 finds a spherical cap volume of 32.589 that's pretty good agreement. The lens calculator does bring up the thought of alternative enclosure shapes employing spherical baffles.
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Tim 

7th October 2018, 03:18 AM  #24 
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Join Date: Apr 2018

A 'pretty good' agreement? To three significant figures the two calculated volumes are identical (32.6)!

7th October 2018, 11:15 AM  #25 
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Join Date: Apr 2018

P.S. No offence intended to Richidoo and tsmith1315!
While the Spherical Cap Calculator better fits the needs of the OP, I take the point that the Lens Calculator is more comprehensive. Spherical Cap Calculator Last edited by Galu; 7th October 2018 at 11:18 AM. 
7th October 2018, 02:12 PM  #26  
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Join Date: Nov 2009
Location: Pune

Quote:
This design is going to be a sealed enclosure. And can work till 80Hz down. They can be used as Satellite speakers with subwoofer or as a standalone bookshelf. (Although not going down to 30Hz.) The link you shared "True Audio TechTopics: Diffraction Loss" was referred. But i had found more detailed measurement document where they provided detail plot. Unfortunately I am not able to find it again. My bad , Should have bookmarked it. I soon would need something that would calculate (simulate) diffraction for sphere. If you know any please help.
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There is always a first time.... Last edited by Aucosticraft; 7th October 2018 at 02:36 PM. 

7th October 2018, 02:14 PM  #27 
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Join Date: Nov 2009
Location: Pune

Yes Driver displacement should be to Vb during calculations.
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There is always a first time.... 
7th October 2018, 02:16 PM  #28  
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Location: Pune

Quote:
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There is always a first time.... 

7th October 2018, 06:54 PM  #29 
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Join Date: Oct 2006
Location: San Diego

I've been able to achieve VERY nice polars by using elliptical enclosures:
The Advantages of a Diffractionless Enclosure They sound really great too. Highly recommended, and easy to make. 
7th October 2018, 10:32 PM  #30  
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Join Date: Jul 2007
Location: 'straya

Quote:
If you want go for the biggest and/or smoothest practical enclosure for optimal diffraction, there's not much point in calculating the volume to 3 decimal places.
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