You guys are on to something. I got a pair of 3.6s about 1.5 years ago and discovered the phenomenon you all are addressing. It barely, if at all, exists on the CS2.2 or 3.5, of great familiarity to me, and subsequently not very present on the CS1.5, 1.6, PowerPoint or 02. I have spent weeks, spread over months, learning about "tinsel", which I called "sizzle". My observations are anecdotal, but quite thoroughly studied and addressed. This sizzle has led me down a rabbit hole into a warren. I have teamed up with Douglas Pauley who has newly patented a technology to manage turbulent fluid flow - in this case air coupling to the room. Big story there, more later.
The sizzle problem revolves around the comparatively large flat area above the 3.6 tweeter, where the 3.5, for example, has none. With a manual or electronic stethoscope, I can hear the problem distinctly as sonic eddies skittling around that surface. One contributor is the mid-tweeter both driving the same frequencies from different physical positions and geometries. I can stimulate the sizzle most readily with female vocal. Yesterday I hung out all day with the Rhino collection of The Trio - Parton, Harris and Rondstadt. The 3.6s are at the north end of the room with the PowerPoints in the southeast corner and my 02 under development on a corner baffle in the same southeast corner. I switch speakers with knife switches to audition same cut, same equipment, same room at same time from the same listening position. The 3.6s are the worst offender by far.
Cascadesphil - my working hypothesis is that dry air and moist air couple and resolve the various forces differently - not a theory, but a hunch developed over the past year of experimentation.
Grille cloth helps a little, but not much. My best solution has been pruned from bunches of ideas and materials, landing on UltraFine UltraSuede on F11 wool felt on the entire baffle. I haven't developed a meaningful measurement scheme, and such may be beyond my resources. I know through study that we're in esoteric territory. Another factor in play is the turbulent waveform launch from the drivers. Various technologies applied to driver bezels and faceplates aid in transforming that very turbulent launch flow into more laminar flow. Substantive improvements there.
There's much more to share, and I'll have some news to report very soon.
