Thiel Owners

Talked several times to Rob about the 10F as the mid-range replacement but never got excited about this option in spite of Rob's claim that it was the best replacement. The difference is size should affect the time coherence even if it may not be audible.

@thielrules, Thank you! What kind of expense would one meet to retrofit the co-axial's to the 3.5's?

slhijb
My pleasure to assist you. Thank You for citing your musical tastes and Rob Gillum's help from CSS.  There are quite a few DIY guys here that are making real progress on finding modern cross-over/driver solutions for their beloved vintage loudspeakers. Take your time persuing this thread, you will find a plethora of information on Thiel Audio 3.5 model.
Happy Listening!

Unsound, the chamber volume for the coax requires almost a doubling of the space that the 3.5 offers for the mid-range driver (using space measurement of the cavity of the 2.7 compared to 3.5). Most practical way would be an expansion of the chamber on the back of the speaker, using a cardboard tube and wood. The front bevel opening would need to be enlarged with an extra inch or so, for which there is enough room. The new coax drivers are about $550 each, not sure about shipping costs. Depending whether you have the tools and skills to do the woodwork, you can estimate your "investment".

Wow the level of expertise of Thiel DIY'ers is amazing .

Thank you @stspur for your impression of Mills resistors with them being your first upgrade .  
They are next on my list .

A correction about the wire used in the Tennessee CS2.7 ,
after replacing the wiring with Cardas 15.5 AWG 
I looked at the original wire using a 30X magnifying glass
and can now see the missing dot making a 16 and not an 18 AWG .

A lot of work replacing all the wiring , 
BUT I'd have to say it's worth it given the improvement I'm hearing .
Jimi Hendrix  "And the Gods Made Love"
never swirled with such detail before .
One more thing ,
I replaced the fiberglass batting with wool quilting batting . 

Rob