Thiel Owners

That series of Classe amps definitely doesn't double into 2 ohms.  I have a pair of the 200s and they were 200/400/500 watts into 8/4/2 ohms.  It's hard for me to imagine 600 watts/side isn't enough.  Much more than that and your amp will be in danger of blowing a fuse.  If you're listening to a full orchestra loud on the 3.7s you may be running up against the limitations of the speakers.  They do fine at a pretty high volume but first order crossovers definitely have volume limitations.

My 3.7s have pink fiberglass insulation in the mid/tweeter compartment.  Maybe switching to wool could be a part of an upgrade?

@tomthiel - Hi, Tom! In another Thiel related thread, you offered to share your take on why there wasn’t a CS4-series speaker. Wondering if you wouldn’t mind sharing that story here?

Thanks again for enriching these discussions!

Arvin

Larry, It's been  a long time, and I might be mistaken, but I thought the late "Bud" Fried also thought 1st order cross-overs were "all wrong". I seem to recall that some of his designs were supposed to be based on transmission line cabinets, yet none appeared to be suitably ginormous enough to be actual transmission lines. Also, wasn't there some sort of brouhaha with Stereophile over the measured bass output of his speakers vs. Thiel's, wherein Stereophile reexamined their procedure; to find that they were in fact correct.

Tomthiel, Interesting that you used Krell's  (though I can understand why)  for developing the CS5's, it's been long rumored it was the 250 Class A Watt mono Threshold 12e's.