Thiel Owners

Tom - your hypothesis is of interest. One observation is that all Thiel speakers mount their XOs to the bottom or back near the bottom with lots of fiberglass between the XO and the drivers / moving air. Plus the sound is hard, like a driver bottoming. When I put the redeveloped XO inside the cabinet, mounted on nylon studs and rubber feet, the problem had vanished. My best guess is some sort of electromagnetic saturation and/or possibly the bottom end of the midrange bottoming out. (But I didn't change the midrange driver, only some specifics of the crossovers.)
As I've mentioned before, getting the XO out of the cabinet does worlds of good. My in-cabinet solution is different from yours - I am suspending each of the 3 small crossover boards in free air, rather than clamping it the the wall where it must absorb the cabinet wall vibration.

With my in cabinet solution the resonance that will always accumulate on a chassis or components suspended or not will be dissipated with specific coupling methods and geometric shapes. For my method to work most effectively the same mechanical grounding scheme must be applied to the outside bottom of the cabinet to the higher mass of the floor. Suspended devices in free air especially under the bombardment inside a cabinet are presented with no path to dissipate resonance so those components will pass that interference on to the rest of the circuit.

Your method does reduce the material cabinet resonance from compounding the air impact resonance of your suspended parts. The free air method still holds onto some of the resonance which then becomes part of the system. Tom

Input accepted. What I know for now is that this rubber-damped / no cabinet contact method performs considerably better than stock Thiel. And that putting a crossover inside a cabinet is an inherently compromised idea. Further improvements always await.

So Tom the Thiel crossover board was screwed right to the cabinet floor? We had a Cs5 in the shop at Ovation because of a meltdown and saw the huge board out never took notice of how it was mounted..now over 20 years ago.
Tom

The CS5(&I) was the exception. It was too big for that. That huge xo board slid into a pair of grooves near the back of the cabinet, abutting a rubber bumper at the top. The cabinet base with a rubber bumper was screwed up against the bottom of the board. I think the long edges were just a light friction fit. Long ago indeed. 1988 introduction = 33 years ago.