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I had done several screw down reso's so I wanted to try the floating cone. I couldn't hear any significant difference. Either way is fun to build and sounds good.
You may also enjoy this discussion we had a while back on adding a piezo pup to a resonator cone.
Oh, and you too, Vick. I guess I was reading this too late last night and thought Huntz had originated the thread. Sorry about that.
(Let's see, 9 hours ago would have been 1:00 am China time. It's 10:00 am here now.)
As for building a simple ring, you could build a dodecagon (12 sided regular polygon) as shown in the following diagram:
This info and diagram I put together with the idea of building a roundish banjo frame. But if you use, say, 0.5cm by 2cm trim wood, you could build a pretty nice looking ring to mount your resonator cone. Why 12-sided? Well, one side per mounting hole, with the mounting hole drilled in the middle of each segment.
That leaves one question: How long should each side of our dodecagon be?
To solve this problem, let's focus on the Isosceles triangle that makes up one piece of our dodecadon pie. What we know are the angles of our Isosceles triangle: 30, 75, and 75 degrees.
Now let's assume your cone is 6" in diameter. To cover it all maybe your ring will need to be a tad bit larger in diameter. Let's say 6.25". So, the two sides of our Isosceles triangle will be half the diameter, or 3.125". So, what we need to solve for is the length of the base of our triangle.
Having forgotten most the geometry and trig I had back in high school nearly 50 years ago, I had to look up how to make this calculation on the Internet. Here is a fairly simple way that uses the sin() function.
How to Calculate the Base of an Isosceles Triangle
1.) Multiply one of the base angles by two and subtract this product from 180 degrees to calculate the angle opposite the base if its measurement is not already given. (We've been given this information, so can skip this step.)
2.) Divide the angle opposite the base by two and find the sine of the result with a scientific calculator.
OK, so 30 degrees / 2 = 15 degrees.
And the sin(15) = 0.2588
3.) Multiply the result of step 2 by two times the length of one of the other sides to get the length of the base of the isosceles triangle.
OK, so: 2 * 3.125" = 6.25"
And: 0.2588 * 6.25" = 1.6175"
So, each side of your dodecagon needs to be about 1.62" wide on the outside edge.
I guess we could test this out by cutting 12 pieces of paper to these dimensions then tape them together to see if they fit the resonator cone properly. This would save trying to cut wood only to find we are just a wee bit off.
Or you can just draw the thing in the diameter you need and measure the parts.