Thiel Owners

The original 3.5’s mids had paper surrounds.

That is very interesting.  I remember my 3.5 mids having a really thin, flimsy surround that definitely did not appear to be rubber.  They seemed to have permanent krinkles in them.  That does not seem like a very good material for a surround, but what do I know.

@thosb thanks - I greatly enjoy this thread and the joyful spirit of music lovers helping each other get the most of of the various systems w Thiel speakers often as the centerpiece.

the most excellent and forthcoming person u got the 2.3 from assured me they had the upgraded double magnet drivers and crossover changes - he knew all about it.
that will be one thing I check IF I break them open....

having fun ...

@thosb. I will add some updated pictures of the vintage room... like most speakers that reside there, some tweaks and changes required to get best of them...
so far the Thiel require more toe in than the Apogee Stage, Vandersteen 1ci or the Quad ESL. The Nakagoka 110 can be a bit tipped up so I swapped in a Grado Ref Platinum last eve... that fixed that... finally my heavily modified Audionics CC2 solid state amp does a better job on the low end....

all fun

more photos later...

the Thiel require more toe in than the Apogee Stage, Vandersteen 1ci or the Quad ESL.

My Vandersteen Sig IIs sounded best with a bit of toe-in but I like the sound of my CS2.4s without any toe-in. I have them just under 8’ apart and sit ~9’ away.

Ketchup makes a very good point. When I reviewed upgradible status for all the models, we nixed the 3.5 due to unavailability of drivers. As long as Rob can rebuild them, that is a safe and effective method of keeping your 3.5s on the air.
A further point of history is that the 3.5 was near the end of Thiel's "normal" driver use. The 3.5 used modified, European, best of form drivers of the day. We had adopted Finite Element Analysis and were developing more sophisticated driver motors, cone geometries and surrounds for greater dynamic range and transient precision.  By the following 3.6 generation, the drivers were completely engineered in-house and custom built to our specs by Vifa. Every driver is qualitatively more sophisticated in every way than those in the 3.5. So, as Ketchup warns, a lot of effort could be wasted trying to find replacement drivers that Thiel was not able to find. The 3.5 has a following. I vote to work with Rob for rebuilds.
I will not be hot-rodding the 3.5, but can recommend upgrade parts for anyone to install themselves.