Thiel Owners

Beetle - FWIW, my experiments have led to a 2-layer system as having sonic synergy. Not ready for prime-time, but anyone is welcome to play.1/8" F11 (or F15N) felt plus top layer of Ultrasuede LT (lightest grade 0.6mm thick). And the clencher is covering the driver plates or bezel rings with Ultrasuede LX (stretchy), right up to the surrounds. Together these surfaces make some magic, both heard, as inner harmonic detail, and measured as lower group delay, harmonic distortion and waterfall decay. Problem is that samples of these materials are hard to get and alternatives (fake Ultrasuede or other felts) do little good. Still working.

@andy2
That's exactly my concern, problematic diffraction effects for the sake of "aesthetic appeal" fly in the face of all I came to know of Jim Thiel's design ethic.  And yes, he was alive and kicking throughout the CS2.4 project.
@beetlemania  
If your analog front-end is up to par with what I read earlier of your amplification, it would seem vinyl would be at least the equally-good source for critical listening!

I guess I'll be paying a visit to a tailor for the first time in decades (!) to try some of these materials.  Perhaps I could just put the felt around the coax's metal perimeter, up to the surround, as there isn't enough space to mill out the grille metal to the left and right of the coax baffle area.  That would seem to defeat the idea though, as I'd be attenuating all the coax output that isn't straight-ahead, vs allowing it to freely disperse unobstructed.  Which takes me back to the compromised 2.4 baffle in its entirety of construction :-|

Andy - my experiments show that a felt edge at the driver surround is not good. It causes its own reflection / diffraction effect. Good results have come from beveling the felt edge and by covering everything up to the surround with Ultrasuede for an uninterrupted surface. Other designers have cut star or odd shapes for the drivers to peek through. But I don't like that either.  I may have spoken too soon. I am in the middle of this stew and perhaps you might sit tight and learn from my progress as things get clearer.

Oops, that reply should have been to sdecker.

sdecker - let's not conclude that the baffle pocket is a sonic problem. In fact, the 20 gauge steel grille plate with its fabric fills that pocket to be flush with the edge curves. The inner edges are not parallel or concentric with the driver, and therefore probably produce little, if any reflections / diffraction.

My work is not to fix anything that was broken in the original design, but to look for ways to add more subtle solutions. One such solution is in the SoftLaunch of the baffle supported wave. I have not dealt with how to incorporate the grille into that scheme, but rather how to optimize the driver / baffle / surface interface. On the earlier speakers the curves are continuous with the front flat baffle and the grille frame is outboard. That's my present sandbox. On the 1.6, I had imagined a solution like the 2.3, which I have not yet seen, but such a solution would also work for the 5, 6 and 7. It's all a puzzle.