Regarding differences between Thiels and Vandys, I only had brief demos of vandy 3’s, 5’s and my newly acquired CS5’s.
my impression was the vandys offered a wider sweet spot but the Thiels have greater clarity. Granted I only have theThiels a short time so I am still moving them around getting to know how they react in my room.
from a design perspective, I read Richard Hardesty’s journals and it seems both Thiel and Vandy pursue the most measurably flat responses. So in short showroom listening sessions some people may opt for other manufacturers non flat responses because they may simply sound exciting ( read: as if the loudness button was pushed on an old 70’s receiver).
other differences I noticed between Thiel/Vandy is that on some models Thiels went the coax route to get single point Source while Vandy went open air mid/tweeter to give some openness (if that’s a word).
i don’t see that Thiel ever applied a rear firing tweeter nor incorporated any of the adjustment mechanisms Vandy used ( settings for rear firing tweeter, multi step equalizer for bass on the Quatros, 5’s). Whoops, just noticed thiel 3.5 have Bass equalizers.
on the note of rear firing tweeter, I don’t get it. Here I am taping blankets to the wall behind the speakers trying to eliminate everything other than what is coming from the front of the speakers To tighten the imaging. So why throw the highest notes ( shortest wave that dies most easily) against the back wall ?
I remember the 70’s Bose speakers that were meant to fire most of their output against a wall to give a wall of sound, hated the way those sounded, like listening to music coming from a neighbors apartment.