Thiel Owners

thosb,

Finally, and there are many on this thread who have better more experienced ears than me, but from what I have heard in my journey so far, "live" comes from tube based amplification.

I always wonder about tube amps myself. The Carver tubed 350 monos keep catching my eye.......But can they handle the 2 ohm impedance?

Thanks for listening,

Dsper

upgrading from a stock CS 2.4 to the CS 2.4SE model.

sdecker doesn’t really have SE-equivalent. The advertised changes were swapping out 13 uF polypropylene + 1 uF polystyrene for 14 uf Clarity SA and 27 uF polypropylene + 1 uF polystyrene for 28 uf Clarity SA. The unadvertised changes were sourcing the boards from FST which reduced the parts quality of the other caps as well as coils (not sure about the resistors). FST were also printed circuit boards instead of point-to-point. It’s also *possible* that the hookup wire on the CS2.4SE was not as good as the original CS2.4.

sdecker kept the 1 uF polystyrenes and used Clarity ESA (instead of SA) to replace the 13 and 27 uF coax feed caps. Probably, sdecker has something *better* than the SE-version although I’m curious to know the sonic consequences of the 1 uF bypasses relative to full capacitance from single caps (ie, 14 and 28 uF). Perhaps Tom Thiel’s trials will include comparisons with and without the 1 uF bypasses.

I don't have full vs 1uF bypass comparisons, but I do have some relevant history. When Thiel developed the bypass configuration, caps were relatively primitive, and smaller value, higher spec bypass caps made a significant improvement. We developed that 1uF tin foil x styrene cap as state of the art and used it for nearly every station. Note that the CS3 had teflon nF double bypasses and the CS2 and 3.5 had styrene ultra bypasses. As caps got better, the ultra bypasses became effectively obsolete. Note that multiple caps help and hurt. They hurt timing precision, since their discharge rate is faster than the larger value, and each station must be tuned. Effectively cost-prohibitive in our particular niche. 

When Jim was developing the SE, Gary and Rob report that they listened to and measured many, many configurations of bypasses and brands of caps including darling  audiophile cost-no-object ones. They chose the then-best Clarity SA for its rightness, both measured and heard. The single (non-bypassed) value was chosen as sonically superior to the bypassed version. Note also that the CSA, with its copper spluttering, is said to be a league ahead of the ESA, which was a relatively small advance over the SA.

Beware that the incision of these higher grade components comes with its own set of potential perils. In Lexington last week I saw Rob's 7.2 XOs in which he had replaced all series feeds with ESAs to compare with stock. He (and his cohorts) preferred the stock parts. The point is that the whole thing is a pot of soup, and "improving" something may require other compensations. When converting Beetle's 2.4s, I was relieved that every upgrade resulted in upgraded performance. As he mentioned, his SE's were late Chinese manufacture with room for improvement by reverting to old methods, from which we also upgraded layouts and coils. All his parts were very carefully selected, and synergy ruled. My own path is with Mills resistors and Clarity caps on old-style point to point boards with new layouts and heat managemnt. I am considering those electronic upgrades as end of project decisions. My focus is on re-bracing and re-baffling which is progressing well.

   It turns out I *did* post to this forum about my 2011 XO upgrades on 2/2/18 (pg 49), with beetlemania and others acknowledging my relatively early surgery. 
   My 2.4s are fairly early production (SN 611,612) so I can confirm the high(er) quality original XO parts (including the inductors), point-to-point boards (literally), and wiring. 
   Due to nobody posting about 2.4 XO specifics in 2011, I had to wing it with only the schematic and XOs in front of me and Thiel telling me their use of Clarity Cap SA.  So I wasn't about to second-guess their use of film 1uF bypasses.  I had evidence the ESA I ended up using was a better-sounding cap than the SA, the CSA wasn't available yet, and the 630V caps and far-more-expensive Mundorfs et al were simply too big for the space on the XO board, so I used 250V versions.
   I don't doubt the XO can be improved well beyond what I've done, but as Tom Thiel points out, there are risks and pitfalls to just throwing the best and fewest parts at such a carefully-modeled 2-way XO.  I look forward to reading what Rob Gillum and team can accomplish with more resources than were available to me at the time!

   And I'm still waiting for informed comments about the compromises of the 2.4 baffle versus the smoothly rounded 2.3.  The 2.7 did away with the baffle discontinuities and should sound that much better due to both the baffle and certainly the 3.7 coax.

sdecker - I don't have those models to inform any opinions. But I am messing with the CS1.5 and 1.6, which exhibit similar baffle differences. The 1.5's grille board mates with the baffle to form a flush surface with 1" radiused round-overs. The 1.6 has much larger round-overs outside of a shallow (1/8" - 3mm) pocket which holds the metal grille panel with cloth over it. I believe the 2.4 and 2.7 are like the 1.6. Within all those variables, I have isolated a sonic and measured glitch caused by that grille 1.6 pocket, either the edge of the metal panel or the edges of the pocket with the grille off. Filling that pocket with 1/8" F11 wool felt eliminates the glitch and the speaker sounds larger, the image lifts and comes out of the box. With the felt in place, the treble balance sounds right without the attenuation of the fabric. The grille magnets work through the felt for protection when needed.

This discussion segues into the grille cloth thing. A manufacturer must decide how to present its products to market, and Thiel chose wood cabinets with fabric grilles, for better and worse. Reticulated foam (model 01, and a Wilson special order) is more transparent, but not very cool-looking imho. Our fabrics got more and more sheer as they became available, but it is still there as Andy mentioned. I believe most audiophiles would prefer no fabric. In fact Thiel offered grille frames with no fabric and extra finishing to match the baffle. Nice, direct sound, but with more high-end sizzle. We could have, but chose not to modify the XO to knock down the treble. A hot-rod shop such as Thiel Renaissance could offer such mods to make the purist happier. I am presently experimenting with solutions that optimize sound quality and aren't physically objectionable.