Thiel Owners

I am seeing a lot of chatter about upgrading the CS2.7 speakers. Can anyone send me instructions on how to do this? In particular, it looks like using the "Clarity Purity 1uf 800v capacitors" is a good upgrade? Where are these located and how would I replace what is currently on the crossover? 

biannuzzi22

Good to see you here again.  Happy Listening!

I have installed the Clarity Purity 800v - S 1uf cap in the mid range circuit and am very impressed , this leaves me with wanting to upgrade a 1.5uf cap on the negative side of the tweeter circuit to a Clarity Purity 250v , one that I already upgraded from an ERSE 250v to an Clarity ESA 250v .  While I don't think this will make much of a difference this will be the last cap upgrade .

Question does anybody have knowledge or experience with replacing an inductor  of a small gauge with one of a larger gauge with the same resistance  ?  The inductors are the only components that I have not changed .   

Biannuzzi22 27june23

"I am seeing a lot of chatter about upgrading the CS2.7 speakers. Can anyone send me instructions on how to do this? In particular, it looks like using the Clarity Purity 1uf 800v capacitors is a good upgrade? Where are these located and how would I replace what is currently on the crossover?"

Crossover upgrades are, at this time, conversational rather than commercial. I hope to eventually have plans and kits, but not yet. The CS2.7 is the final Jim Thiel-esque product, developed after his death, but by the original in-house team with outsourced engineering help, and built in Lexington with traditional classic methods. It qualifies in my thinking as genuine and worthy of upgrade.

Clarity’s Purity800-S is their hands-down winner. Its internal circuitry is more sophisticated than the other PUR caps, plus the thick copper end caps and silver wire refinements. All that said, I find that replacing the stock Thiel styrene/tin - film/foil 1uF ’yellow’ cap with the PUR800 1uF is a lot of money spent on marginal improvement. I suggest you rather might consider unifying the split/bypass cap into a single PUR800-S where most appropriate (eliminating the bypass.) Your best prospect is the tweeter series feed which is now comprised of a 15uF PP and the 1uF yellow bypass. Replace them both with a single 16uF PUR800-S. (That leaves potential for a more sophisticated bypass, in the works, at a later time.)

The weakest link in the 2.7XO is the 400uF electrolytic cap in the midrange feed. I am working on an all-film solution which is not yet ready. My first focus is on early products to keep them up and running. New midranges and tweeters will bring later Thiel driver technologies and longevity all the way to the early designs. As various caps are finalized I’ll announce here. Stay tuned – a lot is presently coming together - I anticipate real progress this year.

Rob - good to see you making steady progress, and eagerly await your report on that parallel tweeter cap.

Regarding coils - bigger is not better (despite conventional opinion.) A significant consideration is the saturation frequency rf wire size. 18 gauge saturates at 17kHz above which turbulence results in distortion, heat and related instability. I consider 18 gauge the best compromise for woofers and OK for midrange with smaller being better and more so for the tweeter. That 20 gauge midrange feed coil is not an accident or compromise. Note the trimming resistors that follow it, so less coil resistance would not be an advantage. Au contraire. The dissipation factor of a coil is far greater than a resistor.

The 20 gauge tweeter feed coil was probably the best compromise between its required inductance and a resistance value that matches an available resistor value. I know that Jim would have preferred a 22 or higher gauge there if practical.

Also note that Thiel inductors were best-of-form from 1978’s model 03 onward. The 2.7 ERSE inductors directly trace their lineage all the way back to 1978 when Thiel introduced ’good wire’ to Acousta-Coil for the 03. At that time what is now CDA101 (highest grade) wire was an aerospace-only product developed for the Jupiter Deep Space Probe by ITT. The rest is history which I recounted in these pages years ago. I don’t think you’ll find better wire or winding, and thicker gauge would degrade performance - and make Jim squirm.