Big thanks to Widget for taking the time chase down the drivers and make these measurements. You’re a gentleman and a big asset to the forum. I really appreciate the consistent help, encouragement and good advice you provide.
I am a little surprised at the jagged response compared to 2404, but then again it’s the great engineering that makes JBL great, not just pretty good.
I wonder if there are things that could be improved upon in the design to smooth it out some? A couple of things I will probably try would be rounding over the lips, and smoothing out the throat a little.
Also, I made a couple measurement errors in the original drawing at the top of the post, the height is really 5” rather than 6”, and the radius is 4 7/8, not 5 7/8.
Here is an updated sketch, showing the no-vane version.