Are any of you following "Thiel Owners" on Facebook? Bill Kranhold just rebuilt his Thiel CS1.2s with new crossover and drivers. It sounds impressive to me. What do the other experts here think?
https://www.facebook.com/groups/129498082096524
His plan: (copy/paste)
"Ok, here we go!
This 1983 Theil CS1.2 was more than groundbreaking for it's time, with true time-coheirent cabinets and crossovers, and an ultra robust cabinet tuned to a really loe .52 Qts (even though it is ported) so it did not have to sit out 5' from a back wall to sound good. The price point was amazing, and the parts quality unheard of at the time. All hand soldered, it was nothing short of a sonic revolution. Everything Vandersteen tried to do without all the compromises.
I am re-purposing this speaker, using a tweeter similar to the CS 2.0 series (Morel, not Dynaudio) and using a woofer similar to the OEM (but more robust yet with a lighter moving mass than the Vifa).
What I have noticed dissassembling the Thiel: The cabinet is amazing. Thick as a brick! The crossover is very good, simple, point to point hand soldered, but, there was no mechanical contection (hooked, twisted) at any of the component joints. Wires just touched. Some of the signal path included very small 20 guage inductors, presumably to 'choke' down the signal and compress it a bit to increase power handling. There were also inductive resistors in the signal path. I won't be doing either of those things.
My crossover is similar, 6db series for the tweeter and woofer, with a 'Fs notch' filter on the tweeter (so I can cross it over lower) and a broad band notch on the woofer (to tame the rising output above 3k).
I will twist and solder everything, with only copper in the signal path, using non-inductive resistor in the L-pad on the tweeter and all 16ga inductors in the signal path.
Shown is the box construction, old crossover, old parts, new crossover schematic, new crossover board, new preliminary crossover, and some pics showing the back-winding of the original coils for re-purposing, etc.
The box tuning should be very close to the original, going down a few hz lower, but I can't be sure till I test it. I will tune the existing reflex port as needed.
I expect this speaker to sound very similar to the original, with a more open sounding tweeter, a faster woofer, and a tiny bit more power handling"
His reported results:
"Success!
Very pleased.
Very balanced, open, with a large image.
Tests well, with a 2db dip 1-2.5k, and rising HF output above 10k.
Used the same filter philosophy as Thiel, 1st on HF with anti-resonance, 1st on LF with impeadance compensation, but added a notch filter for the rising output of the SB driver. Re-used the Thiel 16 and 18 gauge coils, back-winding them to size. Went up in quality on the resistors and caps. Same exact damping and reflex tuning as the original.
It sounds good enough to reproduce a few more !"
