
Home  Forums  Rules  Articles  diyAudio Store  Blogs  Gallery  Wiki  Register  Donations  FAQ  Calendar  Search  Today's Posts  Mark Forums Read  Search 
MultiWay Conventional loudspeakers with crossovers 

Please consider donating to help us continue to serve you.
Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving 

Thread Tools  Search this Thread 
6th October 2018, 11:24 PM  #21 
diyAudio Member
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 11:42 PM. 
6th October 2018, 11:34 PM  #22 
diyAudio Member
Join Date: Apr 2018

Last edited by Galu; 6th October 2018 at 11:37 PM. 
7th October 2018, 01:41 AM  #23  
diyAudio Member
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.
__________________
Tim 

7th October 2018, 04:18 AM  #24 
diyAudio Member
Join Date: Apr 2018

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

7th October 2018, 12:15 PM  #25 
diyAudio Member
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 12:18 PM. 
7th October 2018, 03:12 PM  #26  
diyAudio Member
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.
__________________
There is always a first time.... Last edited by Aucosticraft; 7th October 2018 at 03:36 PM. 

7th October 2018, 03:14 PM  #27 
diyAudio Member
Join Date: Nov 2009
Location: Pune

Yes Driver displacement should be to Vb during calculations.
__________________
There is always a first time.... 
7th October 2018, 03:16 PM  #28  
diyAudio Member
Join Date: Nov 2009
Location: Pune

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

7th October 2018, 07:54 PM  #29 
diyAudio Member
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, 11:32 PM  #30  
diyAudio Member
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.
__________________
This edit signature thingy is seriously hard to find 

Thread Tools  Search this Thread 


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Spherical Enclosure Considerations  romanoaf  MultiWay  13  11th March 2017 11:41 AM 
Which driver in 4L spherical enclosure?  Forane12  Full Range  6  10th December 2015 06:33 PM 
ported spherical acrylic speaker enclosure  neebster  Full Range  23  1st July 2014 12:07 AM 
spherical enclosure  MrSensitive  Subwoofers  94  6th March 2006 08:06 AM 
Materials For Spherical Enclosure  Ignite  MultiWay  15  12th December 2001 09:15 AM 
New To Site?  Need Help? 