Thiel Owners

Rosami and Jon and all - Yes, there are various new crossovers and yes, what is being learned on the 2.4, 2.2, 1.6 and PowerPoint all applies directly to the 3.6. And I have a pair of 3.6s on hand.

My present work includes developing my measurement and listening systems to apply the required rigor to the upgrades.
Regarding your questions of purchase, I can make no comment until the Thiel Audio bankruptcy settles.

pwhinson - I concur with the answers you have gotten, and can add some additional long-view perspective. The 3 moves more air as noted above. Also, the x.7s are more recent and as such include further learning / problem solving in their evolutionary DNA. Each new product stands on the shoulders of all previous work. But a subtle difference between the 2 and 3 is that the smaller woofer and midrange of the 2 gives it an advantage in delicacy; since smaller drivers weigh less and move less air, they are slightly more nimble. That assumes all else being equal, which is never the case; I point it out because over the decades that observation has often arisen. 

I have not yet heard a Thiel x.7, but I expect to be moved if it occurs. Life does not provide the opportunity for most folks to own such expensive tools. I expect to remain happy with my 2.2s and look forward to what their upgrade brings . . . and then there is the 3.6 cooling its heels at the back of the hot-rod garage.

Someone called me yesterday out of his memories of sharing time at CES in the day. He is now an AudioNote, etc. dealer. He has his original 03a which he still loves. He also has 3.5s. He is collaborating with me to create a schematic. Who knows where that will lead.
Did you know that those 03 cabinets were FinPly? Would you believe that in 1980 I experimented with bending those side panels for increased rigidity? There was no way to incorporate such sophistication into manufacturing in the garage shop. But 25 years later the 3.7 made it happen.
Did you know that Jim discovered the dual cone solution in 1979 developing the 04 woofer? . . . a magnificent solution which was dependent on available cones, curved in front x straight in back with identical depth. One went extinct and the project died. But by 1990, we could order a custom molded front cone for the 2.2 - and it happened, and continued to be refined over time, in various models. Such continual cumulative improvement is everywhere - I am pleased to have personally experienced it. 

I among many consider the x.7 coax to be a leap forward in that evolutionary cycle. I wonder if or when it might continue its journey.

Todd - others may have additional SQ comparisons - my contribution addresses other marketplace factors. The design prospectus for Thiel and Vandersteen could be interchanged; they have conceptually the same design goals, launched at the same time into different arenas, avant-garde Southern California and conservative Midwest.
Vandersteen in Southern California was blessed with a robust and sophisticated market with dealers, equipment makers and clientele capable of sorting out the best musical outcomes from the components at hand. So Van took the approach of dual inputs and user adjustability which allowed the audiophile to fine-tune the speakers to their musical taste, room and amplification. The audiophile dealers loved this flexibility and cooperated with Van to get great market penetration. Add to that the enclosure design differences. Van's cabinets were nearly free compared to Thiel cabinets. With the cabinet savings, Van engaged in driver matching and pair crossover tuning. Each Van pair was nearly identical and musical as the next.
Thiel adopted the easy to love cabinetry and high Wife Acceptance Factor as part of its DNA. It was considerably more expensive than Van's approach and it garnered its own followers, but prevented overnight upscaling of manufacture; our cabinet-making required capital and training that simply weren't required by Van. So, Thiel's dealers were a different profile - more mainstream, businesslike and less audiophile - tweek. Thiel's attempt at dual inputs was not successful because inappropriate experimentation by less audiophile users sometimes yielded poor sonic results which were blamed on the speaker. Jim and Kathy couldn't be bothered with such uncontrollable variables and simplified to single inputs, which increased the demands on the driving amp and left the tweakier crowd disappointed. Thiel tested every component to a standard rather than a mate, so a particular pair might be less well matched than a Van, even though it fell within a tight spec window. 

In the marketplace there were many dealers who wanted to represent both Thiel and Vandersteen, and Thiel welcomed that situation. Vandersteen prohibited that product combination which may have been the largest component of the either - or marketplace division.

Although the two brands reach for the same goals in very similar ways, each has its own voice. History says that Vandersteen achieved a far larger audiophile following, but Thiel garnered over 60 design and engineering awards around the world over the years, evidencing a higher level of critical acclaim. When someone asks me what brands to consider I always say Vandersteen.

All else is never equal. Bass inhabits its own world. I haven't seen a 2.7 FR graph, but the 3.7 goes perhaps 5hz (more or less) lower than the 2.4, perhaps 1/6 octave - that's not much. But the tuning of the smaller model 2 enclosure to reach that deep induces more reactivity and therefore more difficulty for amplifiers. The 3.7 bass is an electrically more resistive load than the 2.4, but its absolute impedance is lower, therefore requiring more current. Jim was expert at weighing the interlocking trade-offs to arrive at an optimized system functioning. But each system has its quirks.
All those factors are pretty subtle compared to how much piston is pushing how much air to produce how much bass before bottoming or running out of juice. That bass magnitude factor is the hard limit of each model format. 2.4 more nimble, 3.7 more authoritative.

Another ugly part of bass is that deeper bass, especially when louder, triggers room resonance modes. Deep bass causes problems which can overwhelm that extra few cycles of extension or visceral impact. All things considered, I would personally pursue (if I were in a position to pursue) a sealed bass solution which rolls off more slowly than ports. Reduced amplitude bass is still audible and can add musical foundation while exciting fewer room resonances and harboring less phase shift. CS3.5 lovers come to mind. But the cost of an additional crossover and driver in place of a passive radiator is far from trivial. That's where the well-integrated subwoofer comes to play. A Thiel sub with present-day high-performance class D or H or Benchmark-type THX amp could be very nice. I like Vandersteen's built-in subwoofer - serious cost of entry.
A slice of Thiel history is that we developed a huge folded horn woofer before we developed any salable product. I think I outlined it previously. We were all tuned into the importance of the bass foundation and how the musical harmonic structure develops from the fundamental. But pulling it off within our chosen price constraints was another matter entirely. Also the prototype powered speakers, which I mentioned months ago, produced sub 30 Hz bass with its own woofer-dedicated internal amp. But amplified speakers were unfeasible for us, especially when starting out in the late 70s.

Here's a speculation which I will try to confirm or refute over time: I suspect that Jim's final 7.3 project would have incorporated a smaller-diameter midrange section into the wavy driver, since it crosses to a 6.5"lower midrange. That smaller coax would have been the natural midrange for the 2.5 - remaining consistent with the model development protocol established over the years.

Kent - thanks for the invitation. I don't get out to play much anymore. But . . . thanks again.

bluetone - and all you 3.5ers - the driver quandary is significant; the lack of suitable replacement drivers is why I have shied away from addressing the 3.5, which is otherwise perhaps the central iconic product that Thiel Audio produced. My caution when substituting drivers is this: Thiel products correct and control for resonances and anomalies for 2+ (sometimes 3!) octaves below and above their crossover frequencies in order to produce proper slopes to blend with their mating driver slopes for first order phase, time and amplitude results.

Thiel drivers are extraordinarily specific to their end use and their crossover is extraordinarily specific to the exact peculiarities of its original drivers. On the contrary, a higher order crossover can cope with a generic driver as long as its basic parameters of impedance, sensitivity and so forth are similar to the original driver - because the out of band regions are steeply attenuated and therefore not very important to net performance. 

It is possible that someone could find a replacement 3.5 (etc) driver, possibly better than the original, and then re-engineer the crossover around the particulars of the new driver, and produce a wonderful solution. In my imagination, such a solution would appear. But in real life, I caution anyone messing with these speakers to be very aware of how much the considerable and particular driver variables matter to the resulting performance.

Bluetone, have you overlaid the response graph of the ScanSpeak8525  on the custom Vifa 3.5? Please share the similarities and differences of those two drivers. Does anyone else have guidance for a replacement midrange for the 3.5?

Thanks,Tom

Bluetone - please pardon me, I hadn't remembered that the original 3.5 was from Scanspeak. The most likely source of comparative data would be from Madisound. Can you get a datasheet on the original 3.5 midrange from them? If so, then we could compare the two and there are folks on this forum who might propose valid XO compensations.
As far as I know, Rob doesn't have the original driver specs, which were lost in the ownership transfer.

For my part, I am working with a user who is providing information for me to reconstruct a 3.5 crossover schematic, which will serve as a platform on which to build.

Andy - from my experience, I see no way that any individual, no matter how brilliant or talented, could execute the process that led to the final Thiel speakers. It's hard for people to imagine the immersion, the dedication, the drive and stamina required and expended over decades of full-time work with the inputs, support and sacrifice of a good team of 50 or so people collaborating with external vendors and thinkers and researchers, all working toward the same goal - to substantiate a particular vision. The 2.4, along with additional dozens of Thiel products, represents an incarnation of that actualized vision, physical evidence of an extremely focused creative process applied to the real world.

From an unattributed plaque in a Dallas art gallery:"Love instilled into solid materials by loving craftsmanship is the only creation of mankind to defeat time."
And all of this in the service of, for the love of music. Isn't life a magnificent journey?

Jack - I second Dick Hardesty. When Havens & Hardesty was a hi fi dealer, he did justice to both Thiel and Vandersteen - we were both pleased. He visited Thiel's factory a couple of times and we got along very nicely. He preferred Vandersteen saying that the Vans were more musical on more recordings more often than Thiels. But he also zeroed in on what Thiel was doing, how we were approaching our work. Gone too soon.

Tomic - You are in the driver's seat - I have not yet seen a 2.3. In my upgrades, I am moving the XOs to the bottom compartment with access via a routed bottom panel, taking the drivers out of the access path.

Tomic- Rob has all spikes and spare parts or can supply specs.
Also, if you develop such interest, your 2.3s can be readily upgraded via what we are learning with the 2.4. The 2.3 XO is much simpler with fewer critical parts. Keep us apprised of your 2.3 experience.

Andy - that point of "hotter than they should be" is of great interest. It amazes me that there are no real standards regarding target speaker response - "what should be". The scientific work being done at JBL, the Canadian Research Lab, etc. centers on user preference. Think about that. Record producers second-guess end user equipment and preferences and . . . it's sometimes called "the wild west".

Jim's position was philosophical as much as anything else: that the speaker just like other components should replicate its input signal. At the time that position was quite novel, even controversial, but over elapsed time it has become fairly standard practice with the largest deviations being bass level.

I am not a Vandersteen expert, but it seems that over the years his products migrated from very full bass and steadily falling treble toward flat frequency response, along with KEF, the Canadians and many other design houses. I suggest that a Thiel compared with a modern Van would measure quite similarly, which was not true in distant years past.
The puzzle is not solvable until everybody makes recordings balanced for flat system playback, like Audioquest, Chesky, Reference Recordings and similar knowledgeable producers do. Until that time, it is far safer to balance a speaker rich and forgiving so it doesn't exacerbate recording problems. Jim actually disdained making such a compromise, citing its irrationality, and Thiel took it on the chin in many ways.

Yes, recording one's own or otherwise knowing intimately the nature of your source material is necessary to not get lost in the woods. When setting up my studio this time around, I began with my analog bias built on a vintage Ampex deck. But all things considered, I landed on archival digital. My mics are Earthworks QTC40s (3Hz to 40kHz ruler flat x <50 microseconds settling time) in a coincident stereo array to Metric Halo ULN-8 conversion and stored via ethernet on a Mac solid state drive. MH SpectraFoo is my primary analysis tool with real-time listening (live and/or playback) and visual tools. The simultaneous multi-input environment helps integrate the analysis with the auditory experience, and playback in the recording room minimizes excess variables.

JA - H&H was in Southern California. That's all I remember.

Jim and Richard were both extremely frugal engineers and approached the work very similarly in broad strokes. The largest budgetary difference was the cabinet, which gave Van significant sonic-budget advantages. People compare and contrast sonic particulars; I find it more fruitful to contrast either or both of these product lines against all the other serious contenders such as Wilson, B&W, or the planars and hybrids that completely side-step coherence. Their task is perhaps a couple orders of magnitude simpler and solvable than the time and phase game. They out-sell and over-price Thiel-Van by large multiples, and get plenty of respect from reviewers and the marketplace.

It serves us well to remember that our perspective is peculiar; what some call a cult, what most say is unimportant and un-hearable. Those who 'get it' (appreciate the time and phase aspects of music) generally don't go back. I am pleased that you guys are out there enjoying what took blood sweat and tears to create.

Jon - as I've mentioned before, I have made a study of auditory neurology and experimented with who hears what how. I would say that you 'get it' and in a manner that was formative to Thiel taking on the challenge of coherence way back when. We experienced and observed not only your "relaxing", but also emotional, memory and other musical connections in the coherent presentation which were not present in the phase-time-scrambled (normal) presentation. So, as a subject, your experience would have supported our study, even before we knew what we were studying.

One reason "it" is hard to explain is because "it" is not analytical. In fact the analytical brain prides itself at the descrambling task and a different kind of pleasure built around that cognitive success of restructuring a cohesive sound from its parts. I am drifting toward epistemology - how we know what we know - which is via very a broad count of different mechanisms. I say that the phase-time thing connects us to the music in a more direct, primal, whole manner. And you are experiencing that as relaxing. I call it 'coming home'.  

Over time I am gradually piecing together bits of information. I hope to eventually find those driver curves, but don't have them yet.

Bluetone - Please pursue this 3.5 midrange matter. Make a chart of the # and parameters original driver and the various replacements. As ketchup says the original cone was paper. Kevlar is "better", but its resonances would be different plus it gives up 1dB of sensitivity to the 8640. For perspective, we must find something very close to the original because the whole speaker system (enclosure, xo, other drivers, etc.) works together and changing any parameter of the midrange driver requires re-engineering the xo. That is a possibility as long as most of the parameters match and the ones that don't match are friendly.

This investigation would make lots of people happy. It is not on my current list because of its scope and competing priorities.
Keep up the good work. - Tom

Ketchup makes a very good point. When I reviewed upgradible status for all the models, we nixed the 3.5 due to unavailability of drivers. As long as Rob can rebuild them, that is a safe and effective method of keeping your 3.5s on the air.
A further point of history is that the 3.5 was near the end of Thiel's "normal" driver use. The 3.5 used modified, European, best of form drivers of the day. We had adopted Finite Element Analysis and were developing more sophisticated driver motors, cone geometries and surrounds for greater dynamic range and transient precision.  By the following 3.6 generation, the drivers were completely engineered in-house and custom built to our specs by Vifa. Every driver is qualitatively more sophisticated in every way than those in the 3.5. So, as Ketchup warns, a lot of effort could be wasted trying to find replacement drivers that Thiel was not able to find. The 3.5 has a following. I vote to work with Rob for rebuilds.
I will not be hot-rodding the 3.5, but can recommend upgrade parts for anyone to install themselves.

Beetle - the amount of toe-in is highly dependent on the room. How wide is your room? With enough side space and absorption or diffraction at the first side reflection point, Thiel speakers are designed for straight-ahead positioning. Dropping off the direct tweeter axis smooths out the measured and heard tweeter response. In Thiel's 20' wide showroom, straight ahead sounded best for any and all models.

Bluetone - I would like to add some perspective for  your 3.5s.
As Ketchup alludes, the design is dated in the sense that each product builds on and improves the groundwork laid be its predecessor. Add the problems of replacement drivers, and there is a pretty big pickle. For this conversation I am going to assume that the 3.5s are your speakers which you would like to keep.

One of these days I will get access to a 3.5 midrange or two, perhaps I  might borrow Oblgny's or similar to take measurements. Perhaps Thielrules and I with guidance from this community can zoom in on a best replacement. Rob needs one for just such circumstances. Perhaps between our resident DIYs and myself, we can tweak the XO well enough. If such a team were working on the problem, I suspect we could find a solution better than abandoning your 3.5s. There are probably still over 3000 pair out there which could benefit.

I also want to address Ketchup's assessment of "shouty and harsh". My experience with 3.5s in scores of rooms and shows and studios is that those adjectives do not apply when the system is right. Large excursions of the midrange do come with the first order territory; indeed Thiel midranges have always carried that load - still do in all models. Indeed they eventually fatigue. But within the past year, I have heard stories of people still 'blown away' by 3.5s even when compared with some highly regarded current speakers.

Perhaps you guys on this forum could take on various parts of the task and we might develop a pretty good 3.5 solution.

Yes.

Prof - your interest has inspired me to resurrect and study my 02s which are in transit from Virginia. the o2 is second order like Wilson, ps etc. stock peerless tweeter and normal coils caps resistors woofer and port. Unbraced cabinet, no anti diffraction tricks. A thesis could written on why you like them.

Prof - you might enjoy a little history trip, even if a particular or two might be blurry. The model 02 was a particularly formative step in Thiel's early evolution.
Remember, things were very different in the mid 70s. There was no "high end" yet. Major niches were JBL monitors and Advent coming from academia, geared toward wanna be sophisticates, and Bose promulgating the new paradigm. Thiel's first model 01 was a 10"x 1.5" two way with sealed box equalized bass, 3rd order - very dynamic and efficient (94dB?), but lacking gentleness, nuance and grace. Early advisers counseled that a very different product would attract a very different market and provide experiential input for deciding how to best proceed. We were making up our future on the fly.
Jim designed the 02, somewhat reluctantly, to address these nascent audiophile sensibilities, to be sweet and enveloping and enjoyable. Jim was puzzled by and somewhat resentful that this  experiment was so successful. His heart wasn't really in it, but it hit lots of people's buttons. It was the only product which Jim refused to have reviewed, because he felt it was a form of manipulation of sensibilities, psychological design, re-mixing common ingredients, nothing new. However, as a good engineer, he did give it his full attention. We collectively chose the Peerless silk dome tweeter as it was the darling of the day. The Seas (I think) woofer practically engineered itself to fit the need of second order roll-off and ported bass - so crossover part count was minimal. Our vision was very low cost x high appeal. I designed a cabinet to Jim's enclosed volume specification which left NO / zero waste except sawdust. We even sold the dropouts from the woofer and grille frame rout to recover that cost. The walls were 5/8 particle board to get Jim's volume requirement and yield the palels from standard 49" x 97" sheets. Their retail price in 1977 was $200 / pair in all four standard woods: Walnut, White Oak, Teak and Brazilian Rosewood. That inflates to $885 in today's money. They were a hit.

The 02 served as an influence, a channel to learn what things matter to some listeners who could become our customers. I also have a warm spot in my heart for the 02. The pair coming from my brother is the Rosewood prototype we showed at our first CES - June 1997. The 03 silent prototype we showed there was an 01 in a tower; it never saw daylight. A major reason was the affection and enthusiasm directed toward the 02 by our first public audience. That input was formative and motivating.

The 02 also played a survival function. The late 70s was a financially turbulent time. A particularly wild currency swing caused an imbalance between the German Mark and American Dollar which allowed US products to sell in Germany for even money as in America. So, a competent German distributor came aboard and did a great job selling our fledgling products, 01 and especially 02s, into one of the most sophisticated markets in the world. Italy and England followed. That fact got the attention of some high-profile, top tier East Coast US dealers. They never would have even noticed a new little company from Kentucky, but were eager to take on a company making such good headway in Europe.

The 02 experience caused us to change course in the 03 development. It became a far more sophisticated product than originally imagined. One of the major differences between the 01 and 02 (among everything being different) was the 02 second order vs 01 third order crossover slopes. Second order slopes never exceed 90° phase shift and transition smoothly to the other driver with inverted polarity. There is an ease and rightness about that transition, even though it inverts polarity; there are no abrupt phase shifts or ringing as there are in higher orders. By the way, the newcomer Dave Wilson incorporated the 02 woofer and crossover design into his new "WATT" small monitor. Doesn't that make the Thiel 02 some kind of mythical grandfather or something?

An addendum here is that the 02 precedes our knowledge of pure wire and foil caps, which developed via the rigors of the phase coherent 03. Guess what I'll be doing to my 02s. Do any of you know if that 1" Peerless soft dome tweeter is still supplied?

Prof - Let's not call it disdain; more like chagrin. Their proposition was not his idea and he didn't expect folks to notice their relative gentleness. He liked what he heard and the 02 opened a door toward where the designs went.

JA - the hotrod garage gets some attention every day. I am cooking with a pair of 1.6s and SS-2s with passive XOs. I am using all redbook CDs because the Metric Halo DAC for high res files is in beta revision. Well made CDs aren't too shabby.

Awhile back I asked for and got lots of power amp suggestions, for a second reference and because my beloved and very familiar Classe DR-9s are still in the hospital. They may not recover at least in the foreseeable future. I bought a pair of Benchmark AHB-2 power amps in December and am very happy with them. Although primarily a professional brand, these amps are Absolute Sound and Stereophile class A. As a tool, they do the job I need. Dead flat, near zero distortion, wide bandwidth, phase coherent . . . stuff like that. Presently I am running them bridged for 390 watts into 4 ohms. Their on the fly changeover will allow me to compare various modes of bridged and straight and vertical bi-amping.

The measurement suite is coming together. One corner of my studio is dedicated. There is a pair of PowerPoints on adjacent walls 42" from the corner. A SS-1 smart sub is at the 3-way floor corner, At the 3-way ceiling corner there will be a triangular driver mounting baffle presenting 45° (±) angles to the ceiling, side walls and a 12" wide filler in the vertical corner. The area behind that filler is vented through the floor and the ceiling to de-pressurize the back of the driver under test as well as cool the subwoofer amp nestled into it. The crowing jewel is that this same rig in this corner faces my Jecklin Disk type recording mics which can record test signals from the driver under test or a performer in the same corner for playback through the PPs on the walls at his/her shoulders. Room waves are minimized by geometry and construction. The walls in this corner are outside / building walls topped with 1.5" felted foam insulation. The ceiling is normal drywall. The plywood floor has 3/8" ski-lodge rubber backed carpet squares. It's fairly neutral between reflective and absorptive. The shape of the room should minimize modes. It is an L at 15' wide on each leg. Those walls are sonically porous, made from acoustic tile behind the same 1.5" foam panels. When I get the tools to measure its performance, I hope to confirm my design intentions, which are the most neutral room I can conceive within this given space and my budget constraints. So far it has passed muster with some pretty experienced ears.
Over and out for now.

Beetle - it's been my pleasure. Thank you for providing the focus and motivation to stay on task.

Laserjock - your room will be quite challenging via early reflections. I suggest that room strategy and treatment might be your first priority, with speaker enhancements coming after the beast is tamed.

Prof - I am not sure. Ask Rob.
For my part, I have found a custom replacement for that Peerless tweeter.  I am working on the woofer in the background - I don't remember what it was, but will eventually find out. Perhaps you can find out what Rob has and knows. XO parts should be no problem.

Ryun - I expect you will find good subwoofer advice here. I am not a subwoofer expert, but I have an idea about the nausea you are experiencing.

Researchers have developed Infrasonic Weapons which operate in the 2-4 Hz range which cause nausea to the point of debilitation and death. I suspect you might have an ultra low frequency leak either going into or generated by your subwoofer. If you have a low-cut / high-pass filter, set it around 10 Hz and see if the problem goes away.You can see such low frequencies as cone motion, even though you don't hear them.

Laser - I, also, have not heard either speaker, but can provide a broad outline. As time progressed, each model line (1,2,3, etc.) benefited from accumulating knowledge and solutions. So, in some ways, the latest speaker was the greatest due to benefiting from newly developed technologies, usually in higher-numbered series. The 3.6 is 1993; its tweeter is from the 1988 CS5, and the other drivers are then-state-of-the-art Thiel designs. A 1996 midrange XO change smoothed out the upper midrange. Considered an all-time great. The 2.4 is 2003; its tweeter is from the 7.2 with double-cone coincident coax ideas from the 7s. So, even though the 2.4 is for smaller rooms with less bass capability, it possesses more advanced technological solutions than the 3.6. The 2.4 is an audiophile darling.

If your room is large, you like deep, loud bass and can sit farther away (at least 8'), the the 3.6 might suit you better. If smaller space, closer position and with more delicacy, the the 2.4 might do better.  By the way, they are both on the hot-rod upgrade list for future upgradibility. Beetle and Holco have tricked out their 2.4s. Note that the 3.6 has relatively less room for improvement than the 2.4. The 3.6 stock parts quality is higher.

I hope I haven't buried you in TMI. Context sometimes helps some people wade through complex comparisons. There is no substitute for your own ears, if you can arrange to hear them both.

Bluetone - Yes, it would be instructive and helpful for me to test those midranges as a baseline reference standard. Since I don't have an anechoic chamber, my curves will not match the other published curves, but it will be a step toward progress. The rest of the parts can wait; I am really not ready to take on the 3.5 as a project. Please send a PM to exchange shipping information. Thank you.

Rules - Go for it! I mentioned way back that Jim's first focus and indeed we built early prototypes of active speakers. At that time the market would not accept the concept; now, the time has come. There are many details to tame. I hope that you stick with first order slopes to get time coincident and phase coherent output. 

Please share your driver rig and results. Get your primary curve from free air mounting in a large wall - infinite baffle.

A huge pro of the active approach is taking the guesswork out of cables and amp responses, along with lower cost of low power crossover components.

Keep us informed, please.

The larger the baffle the lower the frequency of the baffle step where the wavelength drops off the edge of the baffle. You can calculate where the 8x8 glitch will occur. Circle is cleaner than square. Put the driver in the middle of the baffle. Now, there's the floor (ground) bounce to copy with; so, if possible, tilt the baffle parallel to the ground, firing the driver upward with the mic 1 or 2 meters away (whichever protocol you use.) Firing up does lots of stuff right if you can manage the particulars. We also used an infinite baffle or ground plane. Hole in the ground with known-sized insulated box in the ground. Compare and subtract low frequency enclosure back pressure against open air performance. That ground-plane "sandbox" provides zero baffle step response, which is what you want to know. Correct the curve for box pressure rolloff and you have the true infinite baffle measurement.
I will repeat that measurement series after 10 feet of snow melts from my neighbor's flat field. Or we can rent the Bell Labs anechoic chamber in New Jersey for perhaps $1K / half day (guessing).

The matter of music and its production and reproduction is very complex, and not readily solvable within real-world constraints. FWIW a story comes to mind. The story doesn't solve or settle anything, but it may shine some light on the depths of the conundrum.

Thiel often displayed with and/or next to Threshold at shows, before Nelson Pass migrated to his self-named smaller operation. Around the mid 80s Jim and Nelson were trading bets at a Las Vegas CES where they bet each other that they could design the other's product better. Jim's first impulse was toward amplifier circuit design, and Nelson's was toward loudspeakers. Jim took it as a joke and went back to work, in the typical Thiel workaday mode. Nelson didn't. Next year he showed up with his Pass Transparent Transducer. The PTT never got publicity, in fact entry to its exhibition room was invitation-only and never more than 5 minutes, and sealed lips promised. You see, Nelson's ultimate solution to distortion (diaphragm and cabinet resonances, thermal compression and all that) was to have none. The air-moving driver was ionized air which moves when excited by an electrical field between wire screens. One driver (air) for the entire range (near DC to whatever upper limit of air's compressability (let's say 100K). Pretty close to no artifacts. The sound was thoroughly enrapturing. Sweet, clean, diaphanous - images hanging in 3 dimensional space, at once solid and ethereal. It was unbelievable.

This was the same time-period when Dr. Hill was showing his Plasmatronic speaker which "burned" helium gas, modulating the plasma in a high-energy electromagnetic field. You can't make this stuff up. Anyhow, Nelson's TT was in its own league in my experience.
There were some "difficulties". Efficiency was low. I don't remember how low, but his custom amp delivered something like a megawatt per channel with special consideration to the seriously low impedances. Maximum sound pressure level was less than 50dB. Another "difficulty" was that it required positively ionized air and produced ozone. So, an ultra quiet exhaust fan came with the territory. And, program material was length-limited, since more than 20 minutes' exposure could lay a listener out with Welders' Fever and worse.

Even though Nelson "stepped outside" the room during demonstrations, he eventually came staggering into our room and , long story short, I accompanied him in the ambulance to the hospital to explain the nature of his illness to the ER doc, who "recommended" to CES that the display become passive.

The point of all this is that the interplay between trade-offs and the depth of required understanding, and the limitations of physical reality . . . make ultra-quality music reproduction extremely complex and difficult. By solving part of the equation, other parts are compromised. Even the One and Only Nelson Pass must make compromises. In our real workd, the listener's assessment is the final arbiter because you really can't get it all.

Unsound - good question. I think that suspicion arises because in later years there was sourcing of parts and some production to China, raising related questions. My general comments are that Thiel products were extremely finished at introduction. Nonetheless over time there were some refinements and/or adjustments for differences between as-designed and as-implemented. A common factor was that drivers' resonance modes might average slightly different than the original prototypes, so small XO changes would compensate.  

Final testing compared every speaker to a standard in an anechoic chamber, which is how various drifting, etc. was identified. As a general rule, quality and consistency improved through the model life, as experience taught its idiosyncrasies.

Yes, the butcher block will work. But remember that the bass will shelve down at 200Hz to lose a little weight as you raise the woofer up from its design height from the floor.

The long-term mutually productive relationship between Thiel and Magnepan may be of interest here. We shared a large majority of our dealers. Dave Gordon came from Magnepan to be Thiel's national sales manager for a decade or more, when he returned there. Both products were well driven by the same source chains. But their presentation was fundamentally different. A Thiel speaker acts as a point source, reproducing what the microphone heard (if we ignore all chain anomalies.) A Magnepan acts as a large dipole, creating its signature sound field in the playback room (augmenting what the microphone heard.) The two approaches aren't really competitive, they are thoroughly different. It is not uncommon for listeners to have two systems, one built around each type of speaker. 

One of Thiel's first reviews was from Scott Estes writing for "The Sensible Sound", who was and remained a committed Magnepan user. He appreciated in print the Thiel presentation, but he wasn't tempted to trade in his Maggies. Hello Scott, if you're out there.

3.5ers - The 3.5 EQ should be repairable. Someone here led me to a DIY schematic - very complete and thorough. I am forwarding that to Rob at CSS in case there might be some additional value there.
Regarding the 3.5 midrange - Rob has samples of a new ScanSpeak driver coming for testing. The supplier says it should need no XO modification. Rob and I will confirm that or devise a xo update kit to make it work. 

Dinopau - hiss and noise from one channel means there is something wrong. Swapping leads can isolate the problem to its source component. If the verdict is noise from the right speaker, the problem is probably failed electrolytic capacitors. They don't last forever, and at ~ 30 years, their life-span is expiring. Direct replacements can be bought from Madisound, etc. for short money.

2.2ers - I received a pair of 2.2s serial #s 2697 & 2698 in mint condition, on loan from an old dealer from my tenure at Thiel . I recognize the veneer that I bought in upland Bolivia. It is a separate species of Pau Ferro which we renamed "Amberwood" to differentiate it from the more common lowland / purple Pau Ferro which we called "Morado". It's hard to believe that someone took such care - they are over 20 years old and pristine. Their use will be as my unmodified base reference as I make changes to my 2.2 workhorses. He will get his pair upgraded in appreciation of the loan.

Dino - you may know that I had axed the 3.5 from my original short list upgrade program because of driver availability problems. However, through this thread and other investigations, I sense that the 3.5, along with the 2.4 are the strongest candidates for an AfterLife. So, they are now on our (Rob and my) radar. Eventually we will have a complete solution for them. Crossover tweaking must wait for replacement drivers, since upgrading crossovers for unavailable drivers is a futile exercise. I suggest that you try to limp along for now and that we will have more good news later.

Dino - I believe the Dynaudio D28AF / 3.5 tweeter is no longer produced. Rob would have an idea of what best to do. We are looking for a long-term solution for that tweeter.

Regarding unsound's correct power information - there is often confusion between steady-state (RMS) and music-power requirements. US's notes all refer to amplifier requirements for musical program, which is transient in nature and therefore does not generate much heat in the voice coil. The huge majority of failures are caused by underpowering and driving the speaker with a clipped signal, which overheats and burns out the driver. The other failure mode is eventual fatigue of the voice coil leads due to long excursions during many years of service.  Someone on this forum mentioned a 7-year life-cycle, which seems reasonable if used vigorously.
Safest mode is a large power amp and reasonable listening levels - turn off if you hear distortion. My bridged DR9s produce 1200 watts into 2 ohms - I don't worry about burning out drivers.

The 3.5 EQ will stay, since it is a vital part of that product. The sealed bass drops off about 100 Hz at 12dB / octave. That would blend very well with a subwoofer, but by itself is pretty bass-shy. The two position EQ extends to 40Hz and 20Hz, which is extraordinary - albeit amplitude must be reduced to avoid bottoming the woofer, which is why the EQ's bass was abandoned as digital sound-tracks came into vogue. In due time I will be addressing the sound quality of the EQ unit. It's a good circuit but could benefit from better signal path components. There is also interest in a fully balanced pair.

I have settled on an order of go. In order to hone my chops, develop hardware and software solutions and walk before running, I have decided to address oldest products first. Their end-of-life is more immenent, and there is generally greater room for improvement than in newer, more advanced Thiel products. So, I am beginning with my prototype 02s. One version will use existing drivers and another will replace the drivers, which are obsolete. There will be cabinet and component upgrades. The 02 pre-dated any knowledge or availability of high purity wire or film capacitors. I will replace all XO components with appropriate best-of-form, keeping the 2nd order XO topology and port, but everything else being fair game. This project should come easier and faster than the more complex models. I hope some folks here will like this - I know I will like doing it. 1976 revisited.

Next will be the CS3/3.5. Since all the drivers need updating, it is likely that we can refit both CS3 (1983) and CS3.5 (1988) with identical drivers and very similar XOs. I'll skip the CS5 and take on the CS2.2 (1991) next. Those products should provide a good foundation for further models. 

There has been suggestions to call these updated models -R for Reissue or Resurrection, or -AL for AfterLife, or who knows what.

-cheers

Guys - I am approaching the 02 first for lots of reasons including access to alpha-testing a new port technology in addition to the MO being developed for the other products. Can this forum provide an idea of how many pairs are out there? How many pairs of 02s are there among you and those you know?

I appreciate your participation.

Tom

Prof - the 02s have not yet arrived due to complications at their Virginia storage location. Should be here soon. A proper resurrection must include new drivers, since the originals are no longer made. I am exploring. I'll stay with fiber diaphragms since part of optimum second order functioning includes diaphragm breakup modes with inverted polarity hand-off.  

Andy - that's a CS6 XO alright. What a beast! I sent you a PM.TT

Andy - I haven't seen the CS6 XO, but can comment generally. Jim employed all pass filters - Zobels and custom - to counter rising impedance with rising frequency as well as shaping networks to trim each driver toward its theoretical optimum response. Over the years, including the first-tier New Thiel period, reviewers, dealers and other knowledgeable folks would counsel Jim to scrap all that stuff. He was steadfast in his desire to create an ideal resistive load. The "amp problem" would be far worse if Thiel's low impedance x first order were to introduce the additional burdens of reactivity.

Our present 'R' approach (Beetle's 2.4s and my PP & 1.6 experiments) is to upgrade all those components. The degree of audibility of parallel / shunt / non-series feed components is far greater than generally believed. Improvement can be heard via a higher voltage cap of the same construction - even in circuits that "don't matter much".

I would appreciate seeing the XO picture and especially comments from you and our other DIYs. 'The veil' is quite delicate and expensive to address.

Beetle - I am substituting caps in the PPs and 1.6s, which directly track your experience.

Cat - for the record, I agree that a subwoofer solves many problems. And for the record, Jim also agreed, but we weren't ready to address subwoofers at that time in our development and, especially then, subwoofers were routinely badly implemented. My reason to keep it in the R series is a tribute to history, the integrated solution at the time.
Note that sans EQ, the sealed bass rollout of 12dB/octave will behave very well with bass management systems.