Thiel Owners

biannuzzi - here's some background that might be useful.

The CS3 and its replacement the CS3.5 share the same enclosure volume and woofer, except for addition of an applied damping compound to the 3.5 woofer, which you can get from Rob. In my opinion, the quality of the native bass is superior to any subwoofer, unless you drive it very hard in a big room and need the sub. That's the purpose of the 40Hz bass cutoff.  FYI: the unequalized -3dB point is 80Hz, falling at the sealed box 12dB/octave for critically damped, authentic bass response. If you have or ever get a 3.5 equalizer, it has the same CS3 parameters, but better circuit design and implementation. I will have an improved EQ later this year.

Many integrated amps have a 'tape loop' for sending a post preamp signal to be recorded (or equalized) before returning to the poweramp input. The equalizer can be inserted into that tape loop with some small signal degradation.

Rob Gillum may know. If so please post here.

biannuzzi22 - PM sent to you.

Tom - My pair has its serial numbers rubbed off, so I don't know if any changes were made later. Mine have the pins I designed for the CS2.2, which is a smooth 1/4" pin with a retention 0-ring seated in a nylon shoulder bushing. That bushing pulls out. I don't remember the bored hole size, but probably 5/16" plain bore.

I have emailed Rob. What little I know goes back about a month. He is swamped with repair work and seems to ignore anything that is not directly billable work related. Same story goes for me too.

sdl4 - distortion profiles are intriguing. More generally various forms of aural masking are intriguing. The aural cortex does somersaults to create the mental image we call ’hearing’. The entire chain from live event to listened experience is convoluted. I am committed to Jim’s approach that those factors are the business of those links in the chain. Unraveling and/or compensating for such problems downstream carries its own down-sides. Many products do just that: compensate for upstream deficiencies. One cost is that some sort of signal resolution or fidelity suffers. Philosophically, I would prefer Nelson to work on reducing upper-harmonic distortion rather than masking it with added lower harmonic distortion, which is more distortion, not less.

I should insert a life-long noticing that distortion is quite often a preference, in sound as in much of life.

I’ll also add that DMP’s founder Tom Jung used CS5s as mastering monitors because they helped him find and minimize those upstream artifacts which conversely would remain invisible via masking by downstream products in the service of ’sounding better’.

More later.

 

I’m not sure about your shim question. I have added shims to both drivers to optimize how the Ultrasuede on 1/8" felt works. Those shims are about 2mm = 1/10" thick. But they are under all drivers, so they don’t change relative driver arrival times.
Thiel’s driver arrivals are baked into the design, and they are virtually dead nuts IF your ear height is as designed = 3’ up x 8’ or more distance. If you have access to a step function generator, and you put your mic at your listening ear position, you can see that the arrival times from the drivers superimposes onto an ideal, single curve. Your ear hears that uniform arrival time as clarity, definition, integrity. Some people can hear deviations in the micro-second range. Some seem not to notice full cycle or more deviations of a millisecond or so.

My present 02 project involves converting its stock conventional flat-baffle launch to a geometry where the woofer is brought forward enough for accurate time alignment. The offset required is 36mm because the woofer is rather deep. A final product might hope to use a shallower woofer for less offset and therefore fewer reflection and diffraction artifacts from the stand-off. That 36mm was estimated by reading the arrival time discontinuity, then prototyping and tweaking until the waveforms of the two drivers look like a single trace.

Have I answered your question?

In response to pieper1973’s query about home-brew cables, I thought it might be fun to recount my escapades over the past couple years. As you know, I’ve been re-evaluating classic Thiel products for upgrade opportunities and have reported many here. I’ve also reported my semi-blind method both solo and with single or multiple assistants: A & B ’whatevers’ are made by me, but the label of A or B is assigned by someone else, who remains wholly blind while I am half blind. First pass is to play any mutually-agreed track and take notes - any notes of any kind to discuss in any terms. Second pass is to reveal ’what’ we are listening to (which might be mechanical, electrical, source, driver, cabinet, wire, room, etc. - anything. Then play A & B again with notes and sharing. Third pass is to share any measurements or background that I had previously developed and, depending on available time, listen again. These sessions are enormously informative because the feedback is any blend of musical, technical, relational, comparative, etc. and these flights of exploration provide avenues of engagement that apply to all the work, not just the system presently under test.

Through 2019-2021 I’ve spent hundreds of hours comparing hook-up wire, while tapping the extensive listening / testing that Thiel Audio performed during the CS3.7 development, as well as my experience developing the original aerospace-inspired classic configuration, and with special thanks to Steven Hill of Straightwire, Thiel’s long-term wire partner, who has been enormously helpful with samples, information, reference materials and sharing his decades of experience. A hardy handful of commercial wires were compared to classic Thiel 18-2 CDA101 (slow-drawn) in teflon twisted at 3/inch. In shorthand, classic Thiel "won" due in part to having been part of the intricate engineering puzzle for the speakers under test. 4 CS2.2s were used in the early stages.

Enter plan B - a different speaker. I was re-assessing First vs Second Order topology via the SCS4 as the second order, coherent entry. By its coincident driver geometry with the tweeter set-back the correct amount, Jim created coincident time arrival and smooth phase transitions while sacrificing only the amplitude of the phase swings through the crossovers. I created two pair of quasi 02s using CS.5 drivers and (modified) crossovers for functional twins where the only difference between A & B was first or second order, respectively. Long story short, I am re-committed to first order (net roll-off outcome) slopes for reasons too complex for this posting.

My wire comparisons got easier using the first order 02s with 1’ sections of wire to the woofer and tweeter from the separate external crossovers. With first order XOs, differences of 1’ of wire could be readily heard whereas with second order, they could not. My suite of measurements also showed differences, sometimes clear, sometimes clouded by ignorance or unknowns - but nonetheless experientially real and correlatable.

Onward to results - wire is extremely complex and functionally impossible to sort out what is "best". My criteria include doing no harm, adding or subtracting no color, texture or character, introducing no measurable effects and offering greatest musical engagement.

I’ll note that I have not explored flat wire such as Goertz. Note also that Goertz is where Jim ended for driving the CS3.7, while retaining ’classic Thiel’ hookup wire.

Highlights:

A) + and - leads are best when identical and integrated in a single run. Note: the signal is AC and integrated. Separating runs introduces asymmetry.

B) Insulation matters. I ended with ’teflon’ family insulations, despite their high cost. Note: I am enamored with cellulose (cotton, rayon, etc.) with possibly lower dielectric absorption than hydrocarbons. (In dreamworld, I land on nano-cellulose for use as insulation, in caps, and driver diaphragms.)

C) twisted pairs in right-twist, left-lay configuration wins. Note: I tried counter-lay, various parallel lays, braids, coax etc. Twist is 'perfectly' executable via reasonable means.

D) Larger gauge doesn’t quite win. Contrary to common sense, lower resistance isn’t the only game. Larger wire gauge exhibits different characteristic impedance. 18 gauge is uniquely suited to audio frequencies.

E) Stranded sounds different than solid. I reaffirmed solid as more correct, but also less forgiving as is often attributed to Thiel speakers. I didn’t like the slight tizzy HF veil and slightly wooly LF fumwp of stranded wire.

I sorted out mechanisms (that satisfy my particular problem-solving approach) to account for perceived differences.

I have a resultant wire configuration that I’m willing to share with interested collaborators on this forum. My apologies to whomever I left hanging during my present shut-down to close up my shop/studio. PMs are appropriate.

unsound - thanks for that link; those guys are serious.

But their approach is different than mine. My interest is in updating and augmenting the original design for better performance and future maintainability while honoring the extant supply relationships we built over the decades. The EQ has several obsolete parts for which I have found modern replacements and am developing an update and an upgrade. More news when there's real news.

The tweeter and midrange were off-the-shelf and are obsolete with no satisfying replacements. My approach is to re-purpose the tweeter from the CS5/3.6/2.2 and midrange from the 3.6 which were 100% Thiel-developed and are the terminal drivers of that discrete driver architecture.

The woofer will (at least for now) remain unchanged. The CS3 woofer was our first ground-up design and substantive collaboration with Vifa. It has Jim Thiel breakthroughs of copper shunts and shaped motor components. Its voice coil is over-hung, since we hadn't yet invented underhung motors; but it has very long excursion, rubber surround and generally built like a tank; and it remains serviceable. Furthermore, its performance in that cabinet is custom engineered and highly successful. The CS3 woofer is upgradable to CS3.5 performance via a polymer cone coating available from Rob.

So, my direction is to implant the Thiel UltraTweeter and CS3.6 midrange, both with possible enhancements along with necessary crossover changes and upgraded parts to achieve performance beyond the 3.6, hopefully significantly.

Of significant interest to me is the sealed bass quality, high system efficiency due to the EQ bass boost, and overall high performance in a very compact package.

Progress is being made.

Unsound - thanks for the spotlight. Indeed his hypothesis of wire corrosion seems plausible and worth trying.

Arvin - congratulations. The KEF Blade 2 is a magnificent piece of design and engineering. It does a whole lot right and I hope you enjoy them thoroughly.

Of course, it doesn't address time or phase, so I trust that you have figured that in your equation. Some Thiel fans get hooked on the coherence stuff and 'don't know what they've lost till it's gone'. (a la Joni Mitchell)

jafant - Yes

The CS2 is the Dynaudio D28AF or later D28/2 which are Ferro-Fluid units.

The CS2.4 coax (I've been told, but not certain) is also F-F

Note there are many different formulae of F-F and only the correct one will keep the original parameters intact. Note also that a specific amount must be used.Too much will roll off the high end and too little doesn't give enough heat protection.

Rob is quite expert, I am not.

Pieper - Thiel drivers are all highly serviceable. FF can be removed and replaced. Your speakers can live on. 

Dspr - I’ll jump in and ask for any and all detail you might develop around this exploration. The ’come alive’ characteristic is something of considerable note in Thiel’s history. After "New Thiel" bought the company in 2013, long-time industry supporter Steve DeFuria came on as sales manager and acting general manager. He experimentally stripped down the XOs of some models (don’t know which) to lose the tight tolerance control that Jim applied to all his drivers. Those simplified crossovers had less stringent frequency response tolerances with less than half the parts count. The listening panel results included "more alive, especially at lower volumes".

In the case of the CS5(i), there are 32 elements in the time delay circuits for the lower and upper midrange drivers. I speculate that removal of those bucket-brigade lines would make the speaker more responsive, but at the cost of time focus. In the 1988 development of the CS5, I wanted to sculpturize the baffle to geometrically time align those drivers. Jim liked electronic solutions - that being his wheelhouse, and we got bucket brigade delay - with 32 extra coils, caps and resistors.

I recall the first Stereophile review by John Atkinson and Larry Archibald who made the 'not alive' complaint. I recall (vaguely-perhaps another product) that substitution of Goertz flat wire raised the veil, as did short cable runs. 

I will speculate that bi-wiring would help this problem. Those 3 woofers take tons of current to nearly 10Hz. The electromagnetic propagation effects of that current on the higher frequency time domain reactivity would be substantial. If you split the signal, I suggest ganging the 3 woofers separate from the other three drivers. Jim would disapprove only if you used disparate cables for the two runs. Of course the ultimate configuration is with 4 amps - two pairs of Benchmark AHB-2s would do nicely. We can always dream.

Your present experience points to a big disappointment in Jim’s career and a prime motivation to adopt reflex bass alignments in the upper end products. From the peanut gallery, I see serious merit in further development of his first approach - sealed bass with various means of augmentation. Perhaps a more refined equalizer? Please keep us informed of your experiments and comparisons with other gear.

dsper - among my blue-sky imaginings for the CS5, you picked the one that is actually feasible. Bi-wiring is not only feasible, but easily reversible if desired. And it's quite simple; the wires from each circuit go all the way to the single binding posts. So, adding a pair of posts  simply requires unsoldering and resoldering 3 pairs of wires at the input terminals.

Dsper- remove the screws and the xo slides out like a drawer. Unsolder all wires from the post lugs and find the drivers with a 6v lantern battery. Install a second pair of posts for the new input.

Mixing amps is treacherous. Gain and other characteristics must match and blend well. Can you conjure two volume controls?

On its way to Bill Thalmann at music technology.

vair68robert - I would also love to hear anyone's feedback about this wire configuration. Anybody have any experience and/or theoretical hypotheses?

Unsound - lots of room for optimism there. Bill was director of manufacturing at CJ while I was same at Thiel. Our companies shared lots of common ground. We'll get the SCD-1 tamed and go from there.

orchardsound - don’t take it personally - he can be hard to get.

JA - change of plans. I got sticker shock for transport cost and risk and decided to deliver it to him when I visit my brother's family in Virginia within a few weeks. I'm taking a 3.5 EQ and schematics along too and pick each others' brains in general.

vair68robert - regarding your wire query - I'll contribute some personal observations. As Thiel's manufacturing director for the first 20 years, then as a purist recordist, and now in my product redevelopment/refinement undertaking, I have perhaps thousands of hours invested in wire assessment and experimentation. That makes me an interested amateur. Having access to aerospace considerations, research and solutions, and a longtime working relationship with Straightwire, I feel OK about commenting.

I had listed some rules from that accumulated experience. This geometry falls emphatically outside those rules. But its proponents have good cred, and their experience should not be minimized. They may have discovered a new way through the weeds of wire. The biggest question-mark for me is the extreme difference between positive and common conductors. Note that our audio signal is an alternating current application. Granted there are differences between signal + and common -, but nothing like DC which presents a clear one-way functional path. The Duelund Helix uses the common - conductor as a shield, which raises multiple technical issues for me as does the radically different conductor lengths and radiating field management between the pair.

Life does not afford the opportunities to run down every interesting approach. I'm not rejecting the possible efficacy of this wire, but it presents enough barriers of entry to keep it in my background - awaiting further input. Anybody heard or used it?

Galen knows his beans. His braided cable is quite similar to THAT ($1000/pair-foot) Kimber braided cable that opened my ears and changed my mind in the early 80s. Is Galen offering flat conductor cable? Blue Jeans accepts returns. Keep us posted.

The only cable I see on the BJ or Iconoclast site is the braided one. That is an extremely difficult geometry to get right. I suspect Galen has gotten it right, and it's worth a try if it's within your budget. 

mrpostfire - I concur with beetlemaina, and can add a few further thoughts. I’ve been critically assessing Thiel speakers for future improvement - so I’ve developed a pretty good handle on them recently, additional to my lived experience in Thiel’s first 20 years and professional use of CS2.2s until the present. Rather than speculating on what you might be hearing, I’ll ask a question. Have you tried to isolate your problem sound to one speaker and/or one driver? It is possible that a voice coil might be slipping on its former. When that happens via over-work / heat, there is a raspy, hazy noise both from the physical motion of the voice coil as well as the large non-linearities of the diaphragm motion vs the input signal. I ask in order to differentiate between a problem and a general observation of "less black". Please supply more information because your commentt runs contrary to the general assessment of Thiel speakers and my experience relative to many peer brands.

Just to clarify for our readers - Beetle's 2.4SEs were late production with FST crossovers which proved to be inferior in some ways to the earlier Lexington units. The coils were not well wound and the wire is CDA102, one step down from Thiel's traditional CDA101 best of form. Otherwise, the FST passive components were CYC clones of the usual best of form units that Thiel had used. I have heard conflicting reports of when and how these Chinese units came about, but my direct comparison between FST and Thiel came out with Thiel sounding smoother, more open and relaxed and delicate, with the FST sounding more etched, crisp and clear. Although both presentations were valid, they did not produce a similar voice.; I would not judge them as from the same designer. My preference is for the original Thiel presentation as more musically enjoyable than the FST presentation. YMMV.

Rob - thanks so much for posting Iconoclast. Lovely Sunday read. I highly recommend anyone interested in what’s going on in cable read these papers. No worries for those less mathematically inclined; all the concept engineering is clear without the equations which can serve as illustrations to non-engineers. I’ll be ordering some to compare and contrast.

Beetlemania - good to see you. I can clarify. All these subsequent caps are way beyond the SE and I agree that dropping ’SE’ might be appropriate for these further upgrades. Jim’s Signature Edition was his late-life offering and the SA cap was the only electronic upgrade. It was CC’s best of its day and won the auditions against other caps including Mundorf and other expensive offerings. Other SE upgrades were the cosmetic bits.

I compared CC SAs to ESA and CSA and reported that the ESA was an incremental improvement and CSA a substantive one. Clarity’s patented PUR breakthrough is replacing the ubiquitous tin/zinc end caps with a tin/copper solution-which is a game changer. Later they added a Van den Hull silver leads option for short money. The CMR is a series cap which uses the same copper end caps. CC discovered that the geometry of the end cap could be improved. In round numbers it went from industry standard (1mm?) to 10mm thick for both the CSA (PUR) and CMR (PUR+). The upcharge is about 20% and said to be a high value improvement. I haven’t tested them due to my present workspace pause, but I am excited.

Regarding your single vs bypass comment - there are trade-offs and as you say, Jim landed on single with a better main cap. The smaller bypass value has shorter discharge time and other reactive improvements, producing a cleaner onset transient than the less worthy larger primary cap. But it also introduces electronic discontinuity in the cap bundle. When the primary cap is good enough, the discontinuities outweigh the timing improvement. In my direct comparisons, one CSA (even the SA) definitely wins, a slight ’capacitor tizz’ goes away.

Jim developed that 1uF cap for the CS5 where it is not a bypass but the capacitive element in the two bucket brigade electronic delay lines that fine-tune the timing of the two midrange drivers. In its day, that was a world-class cap. It became a sonic improvement for following products around our Solens main caps. It got perhaps its best use in the tweeter of the CS3.6 where four of them are bundled as the 4uF series feed block. Today, it lacks the improvements of the new short geometry, silver wire and of course copper end caps. Also, I suspect the post-ELPAC caps may no longer be tin / styrene.

Correction: Second paragraph, second line PUR should read CSA. CC's breakthrough of copper-alloy end caps came with the CSA series.

In small bites. Jim chose the big Krell FPB600. Other muscle amps no doubt 'outperform' the AHB-2. I like the 'grunt' of my bridged Classé DR9s (1100 watts / 2ohms.) Bill Thalmann is presently hot-rodding them. And Nelson Pass is a hero of mine. So then, what's my AHB problem?

Pieter - Higher voltage acts more like film-foil and sounds better. But the upper frequencies have far less power than bass, so difference is negligible. Also the 28uF is in the final station where voltage has been previously shunted to ground. Al in - take what you can get.

 

Duramax - the 2.7 has been talked about informally. As the last of the True Thiel designs it is very mature and, unlike other products including the 1.6 and 3.7, XO manufacturer didn't go to China. Thiel made those in-house with traditional Thiel parts best-of-form parts. There are a couple of upgrade opportunities.

1: The midrange has a single 400uF electrolytic feed cap, which Jim would never have done. That cap can be replaced with by 4 @ 100uF high grade electrolytics. Or, I have designed a 100uF CSA 160 volt which will clarify the midrange but take more room than this layout will handle.

2: The tweeter feed has a 15uF + 1uF PP which can be replaced by a CSA or Purity 16uF to good advantage. That by itself would be the largest upgrade and lowest hanging fruit. There are also shunts to common in the tweeter circuit that would benefit in a small way. The 68uF electrolytic up to a CSA and the 1.5uF PP to a PUR.

However, the 2.7 is extremely refined for what it is, so it's way down the list for upgrading. I could get these components with my next CC R&D order, as well as the 2.4 caps that Pieter is asking about.

Beetle and Rob - In my conversations with DG, the CMR thing was problematic in that in some ways the PUR (CSA with thick end caps) outperformed the CMR. Dave was instrumental in pushing CC to develop the PUR+, which is a CMR with thick end caps. FInalization and pricing has taken forever. I'll get that pricing and post some examples here for reference.

Relax Beetle - let us work through the permutations with apples to apples comparisons. When the smoke settles and the fog lifts we might see some place for some PUR caps, but you're sitting pretty till that time. Spin some tunes with your wife. 

Jim - let's revisit your actual questions:

Tweeter cavity - I don't remember that tweeter mounting having a back in the cavity. It is possible that the early iterations, like yours, had it and it didn't stick or that you have an aftermarket tweak.

The first order of business is to make your tweeter fit, and if you lose that closed back, don't worry about it. If you keep it, a bolt  from there to the back would best be non-conductive and at least be non-magnetic. If yours is magnetic it may be causing more harm than good.

Onward to deepening the hole. Router bits are available with a flush-trim ball-bearing at the shaft end of the cutter. That bearing guides against the circumference of the mounting cavity and can be set to any depth. If you're not equipped, many woodworking shops would have such a setup.

Regarding repair of your EQ. I highly recommend Bill Thalmann of Music Technology in Springfield Virginia. He has the schematic and knowledge for repair. However, some parts are no longer available. We are working on an update. Meanwhile send me a PM to possibly trade yours for one I have here.

cargen - you speculated about using some Thiel PXOs on other subwoofers. Here are my thoughts. Thiel's passive crossover matches the characteristics of the two speakers (sub and main), providing real,engineered rolloff slopes just like the subs were in the full-range speaker. They work very well for that intended use and in the case of the 5-channel PXO5, all the channels are integrated with the low bass. So using PXOs with different drivers with different characteristics than specified by their design would not work well. The magic is that a real crossover is provided because the characteristics of the woofer and main speaker are known and taken into account.

Hi Guys - I'll swing back and answer some loose threads as I find time. Last night I locked the door on my vacated Middle Crossing shop and studio. The building was sold and I closed shop on very short notice, selling 30 tons of wood and some tools and equipment, and storing way too much stuff for further preparation for sale later this summer. Big trip. Looking forward to a simpler life focused around musical instruments and audio. Still a long way to go before the external premises are clear and the excess is sold. Then there's the challenge of finding new space - real estate is extremely thin here in this small, safe, rural New England town where everyone from the city with sufficient means seems to want to relocate. Challenges keep us young, right?

All - regarding CS2.4 production variants - my data is pretty sketchy. (It helps my puzzle-solving if you guys state your serial numbers if you can.) They ran from 2003 to 2012 when replaced by the 2.7. I have records of only 1000 pair, which interests me greatly. The 2.4 seems to be a bit of a audiophile darling, yet its sales are tied for lowest of any model. The SE may add 100 pair (or be included in the 1000 count.) It seems the progression from Lexington to FST / China is around sn 220 - 230. My personal experience along with other collaborators on this forum suggests that transition may partly account for the low sales volume. Reviewers and early enthusiasts would all have experienced the original Lexington units. The later (post 230) units to my ear lack the finesse, delicacy and ease of the originals. I wonder out loud if that discontinuity amounted to anything in the marketplace. It also seems that offshore sales were accounting for an increasing share of sales and that the USA market may have suffered via other non-product problems. Just guessing.

Rob says that Jim OK'd the FST production. But there are also documented stories of heated disagreements between Jim and Kathy as Marketing Director regarding various issues in that time-frame of the 2.4. Tim Tipton (long-term purchasing manager) ventured that Jim's ear was slipping. Cancer doesn't help bodily system performance.

The bottom line is that there is lots of room for improvement in the CS2.4 and with the considerable work already done on it and its forebearer the CS2.2, I suspect those 2.4 owners may be in for a sonic uplift if they so wish.

JA - what I meant to say is that the transition from Lex to FST occurred somewhere around the #225 mark because I heard of a 215-16 Lex pair and a 235-6 FST pair. All the FST parts are made in China, on glass boards with CYC parts. We have previously addressed the particulars;  I consider those FST boards a level down from Lexington boards.

Prof - my notes indicate there were about 1000 pair of 3.7s and 1500 pair of 2.7s sold. I'll comment further when I find time.

jon - Thiel kept quiet about their Chinese sourcing. The Home Theater products has FST parts, then entire boards from the mid 1990s. As far as I know, the MCS was always FST boards. 

Prof - there were many forces at work that limited sales of later Thiel speakers. The story is not easy to stitch together due to loyalties and other factors. My first direct contact in more than 15 years was in September 2012 when the CS2.7 was being finalized. I heard it compared with the CS3.7 in the Thiel listening room. That demonstration and work session was stunning with all elements of the playback chain optimized over a period of 25+ years. Both products were completely Lexington-made, reference prototype quality examples. 

But sales of the 3.7 and other products were very low. The factory was like a ghost town with perhaps 5 people total, mostly working on machines. No speakers were being made. By contrast, when I left in 1995 we had 50 people running a very vertically integrated R&D, production, marketing, sales, service and dealer education program with sales over $6M, 8 new products in the pipeline and sustained 30% annual growth. But things had become very sad by 2012. Many factors play, but not insignificant was that Kathy had taken sales to Crutchfield and then Amazon and alienated the traditional dealer base. Higher priced models were discontinued to simplify the business in hopes of survival for a new buyer. The new buyer emerged at the end of 2012 and the first attempt was to salvage and continue Jim's designs. Steve DeFuria, an early dealer and long-term industry insider was hired as sales manager and managed to re-recruit several strong traditional dealers, accounting for the fairly strong sales of the 2.7 and 1.7 relative to their predecessors. But the new design team changed horses, leaving behind Jim's approach; the reviewers and dealers didn't buy in, and the brand lost its re-emergent industry support. New Thiel poured $10M into their effort to re-brand Thiel as avant-garde lifestyle stuff for affluent young women. It failed.

An example of New Thiel's approach was to position the CS1.7 as a Coherent Source. It was actually a 4th order crossover like myriad other contemporary products. Old Thiel had a first order 1.7 nearly ready for market for early 2013, right after the 2.7 (which is first order) made entirely in Lexington with old-school Thiel components and methods. Part of the reason the 2.7 punches above its class is that the 2.7 has Lex boards and the 3.7 (after about #1100 in 2007) has FST boards. So there are lots of hidden elements in the mix at the end of Jim's life in 2008 and continuing until the demise of Old Thiel in 2013.

Guys - your input is valid and welcome. I don't claim to have answers, only observations.
Prof - I agree that the numbers seem odd. I go on what I sniff out, including Rob Gillum's input. The 2.7 uptick is due to re-emergent marketing under Steve DeFuria.
Beetle - I think you're on it. I know that early FST boards used ERSE coils, caps and resistors, which were made in China, but to very high standards including a best-of-form Japanese PP film, proper coil wire and winding, etc. Later FST including your SE boards have none of that. So quality was being compromized as time went on.
Robert - That 1500 count was from New Thiel reported to Rob. It may not be true or correct.
Jazzman - thank you for all the references. The review cycle goes like this: first production goes to dealers. Review samples come next which is often a few hundred pieces into the run. Thiel carefully tested and ensured those review samples were best of form. (Let's hold that ethical discussion till later.) It was rare for a product to be re-reviewed after a long time into its cycle and when that did happen, the reviewer would have been given home-brewed units with applicable updates. Of course it would be of great interest to directly compare a late FST product to a Lexington tweaked one - but I don't have that luxury. I have developed an opinion that the Lex versions with higher-grade parts and methods are better products.

Beetle- regarding odd 2.4SE variants. Rob has done lots of customer upgrades from stock to SE xo status, either at his shop or providing parts and supervising. He uses CC SA caps, according to the original design when the SA was CC’s best. The CSA is a league up, but n my opinion.

CS2.4 count update: Rob responded that there were about 2300 pairs of CS2.4s made, of which "only a few at the beginning were with Lex XO boards, before buying completed XOs from FST." That count makes more sense.

However it doesn't answer the quality decline riddle. I have (veiled) insider information that after Jim's death in 2009, and possibly earlier, Kathy cut costs in all the products. It is likely that she authorized the change from propylene to mylar caps and lesser coils. Just speculating on who and when, but we do know the what - some later versions were lower quality than earlier ones.

What I would love to know is whether Wes Philips 1991-1992 pair has Thiel or FST XOs and at what quality level. Reviews don't get much better than that one, and Wes was about as good as reviewers get. I'll see if I can tease an answer to that riddle out of Rob. More later. 

snbeall - my understanding from insiders is that the Y2K PCS used the coax from 1998's CS2.3, which probably includes its upgrade to double-magnet status in 2001 onward. (Conjecture: incorporating the 2003 CS2.4 coax would have required XO redesign which wasn't deemed necessary.) Managing so many products (20+) in a small company is an art of its own. 

Prof - I find it interesting to ferret out rather than letting sleeping dogs lie. I'm getting a pair of 2.4s soon and will be able to date them via serial numbers. Their particulars will be of great interest. I suspect with some facts in my quiver, Rob and/or Dawn would confirm or deny my assertions and speculations.

TT

sdecker and all - I gave bad information re 2.4 count. The correct count is around 4500 or 2250 pairs plus around 125 pairs of SEs. Let's please reset our thinking on the CS2.4 success, it was a winner. Thank you for your detail on 611-612 as still being original Lexington production.

snbeall- The PCS was introduced in 2000. If yours has a double magnet on the woofer, that constitutes the upgrade. Interesting thing that double magnet. Its obvious purpose is to reduce EMF leakage for use near a video monitor. However, the reduced stray fields also reduce interaction with the crossover inductors and lead wires for more solidity and transparency, especially with complex and/or loud music.