rule - I would need some prompts to address the lack of braces. The 3.5 development dates from around 1987 - I am unclear exactly when. That's after our first CNC which is when the pierced shelf braces became feasible. I remember front-to-back lumber braces as well as the structural midrange tube enclosure which handle the heavy lifting. The baffle was 3" MDF laminated cross-direction. I remember a lumber transverse cross-brace in the lower area of the sides, but don't remember whether that made it to production. Memories fade. As a side note, the O3 and O3a & b had birch ply cabinets, but I think the CS3 &+ went to MDF. If I saw one I could reconstruct the picture.
The 3.5 pre-dated Stereophile's review analysis (or Thiel's ability to do so) so we don't really know the nature of its resonance behavior.
The 3.5 pre-dated Stereophile's review analysis (or Thiel's ability to do so) so we don't really know the nature of its resonance behavior.