I just scored a sweet pair of CS 2.4SE loudspeakers. Anyone else currently or previously owned this model? Owners of the CS 2.4 or CS 2.7 are free to chime in as well. Thiel are excellent w/ both tubed or solid-state gear!
Past the 100 hour mark on my Mills MRA-12 resistors and it was time to evaluate the sonic difference. I had to do this in mono, comparing the upgraded speaker to the OEM version. Not ideal but the only other choice was to upgrade both speakers and rely on sonic memory. I used Roon DSP to mix the signal into mono. This allowed me to use my “reference” recordings rather than rely on rarely listened-to mono originals (which I also tried). To minimize room effects, I put the speakers close together in the middle of my room, about one foot apart (ie, each speaker had the “same” room interaction). In this position, I simply shifted a couple of feet one way or the other on my couch so that I was directly on-axis. The on-axis energy shifted the balance from what I’m used to (my normal arrangement has the speakers just under 8’ apart with no toe-in) but both speakers were equally handicapped.
Anyhow, I’ve now done two comparative sessions. My impression from both sessions is that the Mills has a fuller, richer sound although my perception of this varied from song to song. I heard little, if any, difference on solo trumpet but a pronounced difference on the well-recorded 2L Mozart violin concerto. Guitars and voices were more "full-bodied" on folk-rock, blues, and bluegrass. More “tonally-rich” might be another way to describe it. On a Chesky test recording, percussions were more emotionally engaging, toe-tapping. The Mills also seems to have a bit more texture or, at least, it was easier to hear into the microdynamics. I think this is related to my initial impression of a "lower noise floor".
All-in-all a worthwhile upgrade - audible benefits and at a reasonable price. I think Tom Thiel’s upgrade path is off to a good start.
What could have been - tomthiel ? Thank You for sharing your Toyota/Lexus story. Frankly, I am glad that you guys recognized the risks and other unknown variables in that particular equation. Perhaps, the venture would have taken away the many wonderful aspects that did become of Thiel Audio? Yes, dealings with foreign countries, friendly or not, is a different animal compared to American industry. Very few politicians are aware of these pitfalls and danger. Happy Listening!
In the late 80s Toyota was building their Georgetown Camry plant and Thiel, IBM, Trane, Square D and Toyota were core members of the University of Kentucky's Advanced Engineering Initiative. What a trip. Also, the CS5 was a big deal in Japan. The chair of the AEI stirred the pot and we began exploring with Toyota a premium audio system for the not-yet-introduced Lexus. Their key people, including Mr. Toyoda, visited our plant, and we developed a proposal. Jim insisted that the best solution was integrated amp / speakers. Toyoda wanted Thiel speakers under the Mark Levinson Premium Audio System umbrella.
The project could have put us in the big-leagues, but the costs and risks of development were beyond our capacity. In fact, we were developing new products at break-neck speed and were production self-limited at 30% year on year growth with qualified dealers waiting in the wings . We couldn't handle it, even if Toyota were interested in our integrated solution proposal.
After Thiel Audio, I was involved as a consultant in a couple of Japanese co-development ventures, and am confident that we made the right decision. Big Japanese corporations are a different animal than small American technology companies.
Most folks agree that DSP is the future. The DEQX site is very impressive as are their reviews. The cost do "do it" actively and especially digitally is a small fraction of analog costs. And precision can be had. I note that ATC gives no phase spec, nor do I see relevant claims from Lyngdorf, but I haven't looked very hard. DEQX may really be doing it. If I were starting a company today, I certainly wouldn't be going all analog/passive! When I find time I'll share the Lexus / Thiel story.
I’ve never heard ATC. Maybe they’re onto something? But I’m skeptical. As Tom Thiel wrote, the steep filter lets you operate a driver in the range of pistonic behavior. This is *highly* desirable (and also requires diaphragm material up to the task). But this throws off phase coherence. There is no free lunch. If there were, all designers would hone in on the same design.
Thiel Audio placed phase and time coherence as a top priority. The downside is that the slow rolloff may not sufficiently suppress the inevitable break up modes. As I’ve written in this thread, I think Jim Thiel made some of the best drivers around. The diaphragms are light and rigid and the break up modes are out of the "main" region covered by each driver. Even at that, some may consider the break up modes insufficiently suppressed by a 6dB filter. Richard Vandersteen seems to have taken this even farther with his carbon/balsa drivers but you need some serious coin to move up to those. The carbon midrange is available only in the 5 Carbon ($30+K) and 7 models ($60+K).
IMO, most of the newer Thiels get it right in terms of balancing phase alignment and pistonic behavior (I’ve heard CS2.4, 3.7 and 7.2 but not earlier models). My ears tell me so, and Soundstage’s measurements of the CS2.4 confirm "very low" distortion despite the 1st order filters. Nothing is perfect but I think Thiel gets you most of the way there and at an affordable price.
That said, if ATC or others have figured out how to maintain phase alignment while also optimizing pistonic behavior I’m happy to learn! I'm not an audio engineer, either. More of a dork with a soldering gun :)
I'm not a circuit designer so I don't know the details either but I've read a number of places over the years that one of the advantages of active designs is that they can actively correct phase so they can remain phase correct with higher than first order crossovers. The active ATCs, for example, describe the filter as "4th Order critically damped with phase compensation." which I think means they are relatively phase correct. After a few Google searches it looks to me like this is a controversial topic. If I were independently wealthy I might spend some real effort trying to understand this but...
tomthiel, I’m in complete agreement with your criterion, demonstration of proper square wave and step response would be required.
I could imagine a tri-amped Thiel with a 3.7’s mid/tweeter and 2 3.7’s 10" woofers above and below as in the MCS except in an hourglass shaped floor standing cabinet with separately adjusted/amplified woofers to correct for floor reinforcement differences, designed to be placed directly against the back wall, or if particular room dimensions permitted in the corners then massaged with individual driver DSP room correction. Oh and it might be nice if the minimal impedance was kept to a minimum of 4 Ohms. The tube guys would like that! Heck, with the prospect of paying for six channels of amplification so would the ss guys.
With very broadband response with steep slopes, a driver could operate in its sweet-flat-pistonic zone. I would need convincing that higher order slopes could be "corrected" to actually produce minimum phase additions through the crossover. I've seen failed attempts, but never a success to my standards. It must pass a square wave right through the crossover, to be phase coherent. If not, then not.
A complicating factor is that unbelievably small anomalies of resonance, less-than-accurate transient behavior and so forth, are readily apparent in a minimum phase system, whereas they aren't even noticeable with higher order crossovers. There's the two-edge sword that Thiel lived with during its entire run. I believe that acuity of perception is caused by the ear-brain interpreting the sound-source as "real" rather than an electronic reconstitution.
Remember, I am not an engineer. I would appreciate being educated as to how the hybrid might alleviate the need for 6dB roll-offs.
^jimthiel, you hit exactly upon what I thought would be the main concern: driver/total loudspeaker correction. I would have guessed that with the co-axial drivers it might not have been too much of a concern with their mechanical cross-overs. The obvious advantage for those models with bass eq's is appealing of course. Perhaps a fusion of active and passive, or just going digital (which could probably reduce developmental labor hours) might be an option. Of course such an option could provide adjustable bass eq for one's actual room rather than perhaps an otherwise unused anechoic standard.
It seems to me that the eventual future is all digital crossovers and active speakers. The idea of active crossovers doing the basic separation and then passive components being added to perfect the signal is interesting. You could have time/phase correct active crossovers that have higher than first-order slopes and then fix driver anomalies passively. If that's ever been done I've not heard of it.
I've got some big active ATC 110 ASLs in another system and they use simple active crossovers. The designer's philosophy (I've read) is that if you make the drivers well enough, you don't need to have complex crossovers. I imagine if you combined the two types you could drastically reduce passive component count and complexity, have the benefit of higher order slopes, and maybe not lose anything.
Unsound, you raise a strong, well grounded germ of an idea.
But in my experience and knowledge, active crossovers are a fairly blunt instrument. Their downfall is that they generally assume a very simplistic model of the
driver and therefore give a very generalized net filter effect without
the necessary interactive nuances between the signal and reactive driver
loads.
Those interactive anomalies can be addressed passively. My study of the
progression of Thiel designs shows drivers that are better and better
behaved as time goes on, requiring simpler crossovers. But they're still not perfect.
As I mentioned way back, Jim's first purest ideal speaker (never brought to market) included separate amps with active crossovers driving each driver with its Zoebel / Boucherot and other corrections attached to it. That hybrid of active / passive offers everything via control of the factors as well as control over or elimination of all the input variables that cause so much trouble (cable reflections, etc.) With the line level signal presented to the inputs, everything else happens "in the box". We decided, as a young, green, minimally capitalized company, that we couldn't afford to educate our customers, as well as the high risk of failure presenting such a wild-card to the market in 1976. Dealers hated the idea of an amp / speaker system that "just
worked". Their very existence depended on addressing all those problems
. . .
History validates our decision. Today, someone might pull off that feat. I offered this idea (indirectly) to the new Thiel ownership, who thought it quaint and idiosyncratic and didn't want to talk about it.
If a savvy group could buy Thiel's intellectual property (assuming it becomes available), and if the engineering talent could be assembled, I think this solution could make some real waves, especially in how it harkens back to the roots of the company. What if pro-audio / record-makers had such monitors? What if we didn't have to make excuses for poorly produced albums? What if the vast differences introduced by amplifier output particulars modified by cable variables . . . weren't in the picture at all? Just dreaming.
It it would seem to me that if one would consider outboard cross-overs then the option of using active cross-overs would seem like a worthy consideration?
Robin, the CS series have enough internal enclosure volume to tolerate the added bulk of the upgraded crossovers. We'll produce upgrades both inboard and outboard.
Good to see you - vair69robert we could not exist without contributors like yourself. I started this thread by a fan of Thiel loudspeakers for other fans of this brand. Keep me updated on your mod/upgrade(s) in the future. Happy Listening!
I would like to say to all Thiel owners on this thread these are the most intelligent conversations I've seen on Audiogon .
For all of you that subscribe to The Absolute Sound the magazine that gave me the dream to own a pair Thiel speakers. In the May/June issue page 18 TAS Legacy Thiel CS5 Loudspeaker, they tell the world about Rob Gillum and Coherent Source Service and on the opposite page an ad for Cardas Audio the cabling that I use , also in this issue page 16 Future TAS my future turntable ( when I win the lottery ) by Merrill-Williams R.E.A.L. 101.3 , that would replace my Merrill Heirloom .
When I retire this summer I will be looking for the upgrade kit for the CS2.7 , I will also be contacting Steve McCormack to see if he has any suggestions for upgrading the DNA-250 amp and maybe I will upgrade the DAC and a lot of capacitors on my Carver SD/A 490 CD player .
Thank You - beetlemania for the additional insight and price-point references. I can agree that the CS 2.4 is very good in stock form. The CS 2.4SE is excellent in stock form as well. Moving up the chain to the 2.7/3.7, one will have to spend in the $20K neighborhood to better those models. You guys have sourced a few of the top competitors from other speaker companies that we can relate. It is good to learn that any Thiel can still compete no matter its age or vintage. Staying tuned. Happy Listening!
Thanks again for additional details -tomthiel. Your hard work will certainly pay off once a prototype is generated. I can hardly await to see a finished product. Staying tuned. Happy Listening!
Note that I am aware that some might want to go farther
afield with cost no object components and others may balk at the significant
cost of my choices. My vision is to find affordable solutions that reach the
next performance / cost plateau.
I will add that I think Tom Thiel’s choices are *very*
sensible. The upgrades will almost certainly (can’t say for certain ‘til we
listen!) yield a significant SQ improvement but without going beyond the budget
of most serious listeners.
Left to my own devices, my choices would have been similar
to Tom’s in some ways. I was honing in on a solution that would have added a
substantial (30%) Clarity CMR bypass to CSA coax feeds. This would have been
more expensive and not necessarily overall better than what Tom outlined. In
his research, Tom has learned that certain bypass practices can have detrimental
effects! Elsewhere, I was going to add small polypropylene bypasses to the
extant caps. Tom’s solution is far better, replacing the electrolytics in the
shunts with the custom 160V PPs. We are fortunate that Tom is able to work with
Clarity to have this cap made to spec. An off-the-shelf solution would be very
expensive and with ginormous caps that would be very difficult to fit.
These upgrades will not be inexpensive ($TBD). All XO parts
are replaced - most caps are custom - except for Thiel’s custom 1 uF bypasses
and the coils. As I wrote earlier, if I were to replace my CS2.4SE with
something new I would start at something like a Vandy Quatro or Vivid B1; $15K
speakers! After these upgrades, I suspect such a search would have to reach to
something like the Vandy 5 Carbon, a $30K speaker. In other words, the CS2.4 is
a seriously good speaker in stock form and optimizing its crossover should
elevate its performance to the next tier (or beyond). Do I want to live with a
speaker whose neutrality, transparency, and resolution exceed or rival anything
up to $30K? And for the “only” cost of the upgrade? Hmmm, decisions,
decisions ;^)
As Tom wrote, some owners may want to go even further.
Earlier I linked to Jim Smith’s outboard XO for his Avantgardes featuring a
rack of Dueland caps and resistors. Would that approach outperform what Tom Thiel
has outlined? I hope so – that’s at least $20K in parts! But we’d have to
listen to know for sure. To my thinking (and budget) that is not sensible for a
CS2.4. Maybe you CS3.7 and 7.2 owners will choose to push the limits? But
remember that Tom Thiel’s “base” upgrade is a notable upgrade even for those
models.
later production 3.7s have Chinese made crossovers which
seem to have some polyester caps where polypropylenes are specified. And those
are built on printed circuit boards
My SEs also are on PCBs and with some MKT caps where Jim
Thiel’s schematic specified PP. My pair was built in 2012 (the year Kathy
Gornik sold Thiel Audio) and are among the last SEs built. @jafant I suspect
your pair are similarly equipped. For us, Tom Thiel’s upgrade will probably be
an even bigger jump in SQ than for owners of earlier SEs.
Prof, thanks for the reference to Phil Bamberg. He is part of the picture and solution of the puzzle. Your quandary of 2.7 vs 3.7 shines a light on some design particulars of interest. The 3.7 has no electrolytics in any signal path, whereas the 2.7 has bypassed electrolytic midrange feeds and an unbypassed electrolytic in a tweeter shunt. Our target caps will surpass the 3.7 quality for both 2.7 and 3.7.
Of further interest is that later production 3.7s have Chinese made crossovers which seem to have some polyester caps where polypropylenes are specified. And those are built on printed circuit boards, whereas all 2.7s are Lexington made on point to point boards. I associate sonic "ease" with point to point implementation.
The purpose of this post is not to overwhelm with detail, but to share some parts of the emerging puzzle. I am hopeful of achieving significant improvements via parts quality and implementation improvements.
Thank You for the updates - tomthiel keep up the excellent research and work. There are several guys here that expressed interest in updating/upgrading their xo networks.
@tomthiel & @beetlemania - Please put me down as a definite "Yes"! I am concerned with the point beetle made earlier regarding how my 3.5's must be pushing 30+ years old by now. I had just recently had their Electronic Bass EQ overhauled by Rob at Coherent Source & the sound quality improvement was instantly noticeable.
My feeling is that our Thiels, which have always been so revealing & resolving of the sources and material we "fed" them, will show similar improvements with the updated crossovers you guys are working on. At the very least, it will add more years of "life" to these classics.
Thanks for the updates and good luck on your project!
Thank you all (I'm from Kentucky) for your participation here and via PMs. Here is a progress overview. Indeed a high priority is to avert losses from aging electrolytic caps. New work will have ALL film caps for indefinite product life.
In broad overview, all series signal path caps are ClarityCap CSA-630 volt. They have excellent technical and sonic performance at justifiable prices. I am bypassing with the custom 1uF styrene that Thiel had made from best German film, now defunct. We will salvage your old ones. I will be double-bypassing with 1% fractional value MultiCap styrenes. Thiel CS2, 3 and 3.5 used this trick with MultiCap's predecessor. Jim dropped out as of the 2.2. I'm back in for the quicker and quieter leading edge transient at what I judge as justifiable cost for this upgrade scenario. Shunts to ground in Thiels (pre 3.7 and 2.7) are electrolytics bypassed via that 1uF styrene. I am going with a custom ClarityCap polypropylene having all CSA factors but with a 160 volt film for manageable form factor and cost.
As beetle has mentioned, all resistors are being replaced with Mills MRA-12, an excellent and cost-effective solution.
Note that I am aware that some might want to go farther afield with cost no object components and others may balk at the significant cost of my choices. My vision is to find affordable solutions that reach the next performance / cost plateau. This project is larger than may be obvious. This relatively major redrawing of the rules will require re-voicing both via measurements and listening. Beetle's 2.4s and my PowerPoints are the first line of that work. Our custom parts will arrive early June, when we'll engage the core work and begin substantive feedback regarding our judgements to date.
Always a good thing to have another Thiel owner on board, especially, one from Lexington KY. I look forward in reading more about your Audio journey. Feel free to post more about your system and musical taste(s).
a simple yea or nay will work for your purposes. The finer details, instructions and logistics, can be worked out down the line for you and tomthiel. Thank again for taking the initiative on this interesting tasker.
Actually, yea or nay *might* well work for everybody :)
In the case of the CS2.4, Tom Thiel has worked up a
one-sided layout for internal installation and a two-sided layout for outboard
installation, the latter to save space and enhance the chimney effect for
better cooling. As these will be DIY kits (or, I imagine, send your speaker to
Coherent Source for the work) there is a good chance we can each go with our
preferred installation. The XO parts list will be identical, it’s just a matter
of layout and extra connections in the case of outboard. Tom wondered how the
community would react to outboard as an option and I think he now has an idea.
Again, the advantages of outboard are isolation from
physical and microphonic resonances, improved cooling, and increased options
for further cabinet bracing. The advantages of internal installation are reduced
upgrade cost (no extra cabinet and connections) and no added box to reduce WAF.
@unsound Glad you find my updates informative. Your CS3.5s must be close to 30 years old - I understand your concern re: cap life. That should further incentivize you to seek Tom Thiel's upgrades as they become available.
Beetlemania, first let me thank you for your informative updates. For those of us with older Thiel’s let me say concern over failing caps, etc. is of primary importance. Keep up the good work.
more urgent for older models as their cross-overs are likely to be needed (due to age)
Good point! I see that as a secondary benefit. The intention of the upgrades is to notably increase the quality of the passive parts and, thereby, the SQ. As Tom Thiel wrote earlier in this thread:
Thiel was always about finding the optimum point on the cost-performance slope so that real music lovers could afford our products.
Speaking for myself (and not Mr. Thiel), the upgrades seek to maximize SQ beyond what was possible at the price points of the original products. IMO, a cost-no-object approach to the XOs for the CS7.2 or CS3.7 would have likely have placed those speakers on par with the best available. The upgrades intend to seek to squeeze the ultimate SQ from the designs.
I am still burning in my new resistors, so don’t yet have a final verdict but my initial impression is that the Mills MRAs are a worthwhile, yet subtle, improvement over the ERSE resistors originally installed. This change in parts would have added $200-300 retail to the CS2.4 and represents, I think, the kind of decision Jim Thiel would have made when optimizing the “cost-performance slope”.
In my case, I recognize the drivers in my CS2.4s are really frackin’ good. IMO, I would have to move up to something like the Vandersteen carbon or TAD beryllium drivers to find something clearly better. Speakers with these drivers are an order of magnitude more expensive than my Thiels! But I think I can get really close to their level of performance by optimizing the XOs. In other words, it's a solution that gets me close to the very best but at a price I can afford.
Also, keep in mind that the technology has advanced since Jim Thiel designed the original XOs. Even the relatively recent Clarity SA coax feeds in my CS2.4SEs have been notably surpassed by Clarity CSA.
Not that it gives you any more information per se on the Thiel 2.7, but maybe of interest to you is this post in another forum by Philip Bamberg who worked on the 2.7:
I designed the crossover for the CS2.7 upgrade to their coax mid/tweeter
driver. It was not easy. I was present at the voicing sessions in
Lexington, after some listening in my own house.
I can vouch
for both the CS3.7 and 2.7 speakers having a 2dB/decade downsloping
response from 200 to 2kHz, transitioning back to level in the treble.
This is a tonal balance curve similar to many high-end speaker brands.
However such a speaker still does not sound dark (there are other more
technically involved reasons for this).
One shining performance
feature that I can vouch for with the CS2.7 -- the bass is
spectacular. Their 10" woofer RULES, and the cabinet alignment is
excellent. Play acoustic bass or drums on this speaker to believe me.
Also,
the coax unit is impressive in its own right. The midrange is actually
flat to 20kHz (without crossover). I think the time-coherent acoustic
alignment and fast response drivers may lead to the listeners' reaction
of bright or forward.
Thiel also spends for PP and polystyrene
bypass caps for additional transparency. For these reasons, system
matching is a bit more critical with the upper Thiel models. Also, all 3
drive units have aluminum diaphragms. I promise you that I addressed
the woofer ring, and achieved excellent time and phase coherency - Thiel
was quite demanding of this as you can imagine.
While I
performed some reverse engineering of a few of their models (part of a
technical familiarization of Jim's work) I am not intimately familiar
with the design and history of all their models. I suspect that their
models over the past dozen year vary in tonal balance, and that it is a
mistake to conclude that the company voices speakers to be
bright/lean/forward overall. IOW, I think the time for audiophiles to
conclude that Thiel = Bright should come to an end.
I am no
longer under contract for Thiel, and I gain no benefit from their
sales. These are just my own objective and subjective observations.
Yes or nay doesn’t work for me. It depends on the form factor. I would think that cross-over updates might be more urgent for older models as their cross-overs are likely to be needed (due to age) as opposed to newer models that have plenty of life in their current caps, etc.
I have chosen the CS3.6 for its more sophisticated proprietary drivers and more accessible solutions.
Interested in internal upgrades for my CS3.6s.
Tom would like input from the larger community as he finalizes his plans. So, please respond “yea” or “nay” regarding outboard crossovers so that he can gauge interest.
Not so interested at this time but might be in the future.
There are substantial differences applied to the coax by the two designers and/or assemblers. I have Jim's 3.7 schematic + layout, but only a designer layout for the 2.7. The 3.7 was all Thiel in-house and it seems the 2.7 was outsourced to ERSE-USA. To correlate what this community hears with the fact matrix I am assembling, I would appreciate detailed photos of the crossovers of both models to learn parts quality of the various components. The simplest method for me is via email - tomthiel@worldpath.net. Thanks for your help.
thanks to Tom and everyone else. I agree about the two speakers. at this point of break in, my girlfriend likes the 2.7's better and wants to keep them. I am very fussy about the sound of the cd's i have and most are pretty well recorded, and i think the 3.7's will allow me to hear deeper into them and enjoy them more. they are getting better but need more time.
Much Thanks! to you, beetlemania and Mr. Rob Gillum for taking on the task and project of building xo for our beloved Thiel speakers. What fun you guys must be engaged.
nice score on the CS 3.7 model. I know that you will enjoy this loudspeaker. I know that you will find a good home for your CS 2.7 speakers as well. This is an excellent opportunity for another music lover to discover Thiel loudspeakers.
Keep us posted as you massage the 3.7 into your system/room.
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