Hello peeps,
been looking into making some ikea bowl spheres as a simple full range speakers
but....................
was wondering what would
BLANDA MATT Serving bowl - 12 cm - IKEA
on top of this
SEKIN Serving bowl - IKEA
would this work good? or is it bad for internal waves and such
been looking into making some ikea bowl spheres as a simple full range speakers
but....................
was wondering what would
BLANDA MATT Serving bowl - 12 cm - IKEA
on top of this
SEKIN Serving bowl - IKEA
would this work good? or is it bad for internal waves and such
Full sphere is smoothest. Cylinder is only good if used on end. Mounting the driver like a Bazooka is horrible. See Olson. Actually, search on "Olson diffraction" and look at the various sites. Everyone sites his original paper because he did it correct the first time and no one has anything much new to say!
Boxes can be made to behave very well with big round over bits or clever application of 1/2 inch thick felt.
Boxes can be made to behave very well with big round over bits or clever application of 1/2 inch thick felt.
HI,
I fail to understand. What you mean say with ''used on end'' and ''Mounting the driver like a Bazooka''??
Sphere is the best shape wrt 2pi to 4pi transition ripple of the shapes Olson tested (ie looking only at the outside, the inside is a bad shape). Teardrop (as per B&W) is better and doesn't have the same internal standing wave issues that a sphere has. Driver mounted on the end of a cylinder is bad, driver mounted on curve of cyclinder is much better but not as good as rectangular box with big champhers.
Page 23 Olson
OP's suggestion of half-sphere on truncated cone is a good one, this is closer to teardrop (add a duncecap on the back-side to finish it off). And on top of that you save £9 per speaker.
dave
Page 23 Olson
OP's suggestion of half-sphere on truncated cone is a good one, this is closer to teardrop (add a duncecap on the back-side to finish it off). And on top of that you save £9 per speaker.
dave
The sphere is NOT the best! In order of worst to best..1) Sphere 2) cube....3) all others 4) A calculated best Acoustic ratio 1.2599-1- .7937.
Think about it... the sphere will reflect internal waves from a point source to the walls (At equal distances) & all arrive back to the same place, in phase, equal intensity....This will compound & concentrate the back-wave...Same somewhat with the cube. An acoustic ratio breaks up these frequencies by a mathmatically derived proportion.
_____________________________________________________Rick.........
Think about it... the sphere will reflect internal waves from a point source to the walls (At equal distances) & all arrive back to the same place, in phase, equal intensity....This will compound & concentrate the back-wave...Same somewhat with the cube. An acoustic ratio breaks up these frequencies by a mathmatically derived proportion.
_____________________________________________________Rick.........
One potential complication: the cone needs to be the same diameter as the bowl, no dimensions are given.
dave
Beware anyone who cites Olson on diffraction, especially when they mention US Enclosures in the same breath...YMMV.
Olson used a point source (2" diameter) mounted in the center of his ~24" baffles. This overstates the effect of diffraction in most cases.
If you move a piston in the end of a cylinder slightly off-center, diffraction performance becomes surprisingly good, as does the off-center performance on many of his examples. When a source takes up a large percent of the baffle, shape becomes rather unimportant.
Olson used a point source (2" diameter) mounted in the center of his ~24" baffles. This overstates the effect of diffraction in most cases.
If you move a piston in the end of a cylinder slightly off-center, diffraction performance becomes surprisingly good, as does the off-center performance on many of his examples. When a source takes up a large percent of the baffle, shape becomes rather unimportant.
The sphere enclousure is the best sound why it had no flat walls inside to amplify the resonances, which funnel down.
I fell you would say rectangular Golden Ratio box is good, but these proportions you mention are strange.
hi,
so the hemi-sphere bowl is Dia 28cm with a 13cm height
and the cone shape bowl is Dia 28cm with 13cm height
my first thoughts of using these was to make a crude B&W'esc teardrop cabinet
going to buy some this weekend so i can measure the internals
Cylinder Subs
Few years back I found a huge PVC drain pipe, 15" ID 1/2" wall (still have 4' left). I made several BR subs with 8" and 12" woofers.
They worked okay, I didn't see any advantage over a rectangle box. I had some pics, but must have delated them.
I would add if sphere is the ideal speaker inclosure, there would be 100s of them available in stores, web, etc.
Few years back I found a huge PVC drain pipe, 15" ID 1/2" wall (still have 4' left). I made several BR subs with 8" and 12" woofers.
They worked okay, I didn't see any advantage over a rectangle box. I had some pics, but must have delated them.
I would add if sphere is the ideal speaker inclosure, there would be 100s of them available in stores, web, etc.
The sphere is ideal only in how it manages baffle step and diffraction. We can beat boxes into submission and they pass the WAF easier. There are spherical speakers on the market.
This is pretty simple physics. Just go read Olson's paper. It has ONLY to do with diffraction and baffle step. No magic, golden, Fib sequence, smoke and mirrors. Like I said before, his original work stands so well, no one has needed to revisit the subject. Just read it.
BTW, a sphere with a wad of damping in the center works exceedingly well. Also note that internal reflections are no where near as important as the external problems Olson addresses. Not unimportant, just not as.
This is pretty simple physics. Just go read Olson's paper. It has ONLY to do with diffraction and baffle step. No magic, golden, Fib sequence, smoke and mirrors. Like I said before, his original work stands so well, no one has needed to revisit the subject. Just read it.
BTW, a sphere with a wad of damping in the center works exceedingly well. Also note that internal reflections are no where near as important as the external problems Olson addresses. Not unimportant, just not as.
Bews and Hawksford, Lipshitz and Vanderkooy, Juha Backman, just a few who have published analytical papers in the JAES since Olson's rather crude empirical work.
I went through all 4 volumes. You know, his "crude" work has everything this thread needs except getting a few people to actually read it. If you can mention a specific paper that adds to this conversation, let me know and I will revisit it.
So for those too lazy to do a simple search:
Diffraction Information & Graphs
So for those too lazy to do a simple search:
Diffraction Information & Graphs
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