Thiel 2.3 vs 2.4 the real difference

Ok, there were some arguments around, some even so hot that point was missing. I am very curious what difference can be found between the two. I have a chance to upgrade mine 2.3 but would like to hear from you first. Any switchers like me have something to say?
What parts can you upgrade from 2.3 to 2.4? The passive radiator is oblong on the 2.4 and round on the 2.3, right? I know there is an upgrade on the 2.3 that I haven't gotten which includes new coaxial drivers and changing a few parts in the crossover network. An older Audiogon thread says the upgrade is an improvement.
The tonal balance is quite different between the 2.3 and 2.4. The 2.3 still has the older Thiel hyper-analytical sound; the 2.4 retains the best aspects of that sound but leavens in a degree of warmth missing from older Thiels. Certainly worth a listen in person-- if going back to Thiels (I had CS2s for 16 years before moving to Vandersteens) I would definitely choose the 2.4s: they're a kind of middle ground between the older Thiel sound and the newer Vandersteen sound (perhaps a third of the way over towards Vandy warmth).
'Upgrade' I mean selling 2.3 buying 2.4. Hope you got it now..
I have CS 2.3s that I upgraded a while back with the improved drivers and crossover parts. It really did not sound "more musical" as Shari, with Thiel, said it should but it did seem a bit more 3D and palpable. I have listened to the CS2.4s in two different locations and they sound a LOT like mine. Hard to tell if they are any better without putting them in my room, they sounded that close. I love how many people hear a speaker in a foreign room and then pronounce judgment on minor changes in sound. For what it is worth, I tool think Thiel can be bright with lots of CDs but, when I check out the competition, Thiel still carries the day. I keep checking bright CDs on my Sennheiser HD580 headphones and they often sound even harder on those.

Tim McTeague
It was a nice opinion Tim.

The problem is I very much like my set-up. A few days ago I upgraded CD playback to Meridian G08 and it keeps me listenig all the time. I have one small restriction however. I think I would like a little bit more air or energy on top. Sounds pretty outrages with that common Thiels are bright 'knowledge'. I am affraid if 2.4 would contribute to even less open mellower sound. But it seems like I could have a great trade-in opportunity on my 2.3 I wouldn't like to miss.
I've owned many Thiels including 2.3's, and my good friend owns 2.4's. I think Swklein nailed it in his comment; the 2.4, to my ear, retains the best attributes of Thiels while being a lot more willing to sound musical with a wider variety of gear and source material. So I think there is no question that it's an upgrade, but, the question is how much of an upgrade and what would it cost you. I would personally pay the difference between used 2.4's and used 2.3's in order to have 2.4's. By the way another interesting alternative is 1.6 with a used REL Strata III sub : - )
Its pretty simple to figure out how they differ,

Just look at the Stereophile measurements of the CS2.3's versus the Soundstage measurements of the CS2.4 and one can quickly see the evolution between the two speakers. The CS2.4 plays with considerable less distortion and clarity than the CS2.3 and you may be right about is soun ding softer.ack of distortion will do that.


"I have one small restriction however. I think I would like a little bit more air or energy on top. Sounds pretty outrages with that common Thiels are bright 'knowledge'. I am afraid if 2.4 would contribute to even less open mellower sound."

You may need to calibrate your sense of reality, the CS2.3's are +10dB by the time they get to 20khz and +15 to 18 dB from 1 khz depending on the individual speaker. Now you can make your system sound any way you like but if your goal is a semblance of "accurate" you need to rethink your instincts and or maybe get your hearing checked just so you have a baseline for what you need your system to do.
Because you may very well be right about needing the tipped up highs. A hearing test will cost less than the 2.4 upgrade especially if for you it was the wrong move.

The more you know the better the decision you can make.
Cinematic s.
Thank You for your concern but my hearing is just fine.
I understand why people can call Thiels bright cause I had them bright in my system before when paired with wrong components. To be honest I also had them dark and dull with some other stuff.
The last change I made was to get rid of old CDP and that brought HUGE improvment. I cannot belive what impact had made Meridian G08 on my system. Everyting is almost perfect but until you try you never know - that is why I want 2.4
The Stereophile measurements of the 2.3 were an anomaly. No other magazine showed the radical climb towards the treble that theirs did. I have used a Radio Shack sound meter and test CDs to chart my 2.3s in room and the speakers are remarkably flat. They actually look like they are down in the high treble until you add in the corrections for the Radio Shacks own tendency to be off at the frequency extremes. Also, check out the reviews of the 2.4. The brightness issue is mentioned in nearly every test, which was not the case with lots of the 2.3 reviews. Look at the NRC graphs on for interesting comparisons. Lots of speakers have, lets say, unusual concepts of flat. Thiel has no dip in the presence region that many do and thus come off bright by comparision. Together with the tendancy of CDs to be recorded a bit bright, for various reasons, and the package can make for a hard sound. But, when good recordings are played through Thiels the result can be wonderful.


CD's are not recorded bright unless they are top 40 bound and my MLSSA and SoundEasy with B&K speaker measurement systems showed a dip and a rise on the four different pairs of CS2.3's I measured. In room response was ragged because off axis dips were high in Q causing excessive sibilance and other noises especially when the speaker was having to strain a little.

The CS2.3 was considerably brighter (to a fault) than any Sonus Faber, Dynaudio, Revel, Vienna Acoustic and Meridian speaker in the store. Personally I blame the lack of cone area as the biggest problem and distortion in the concentric driver.

"Look at the NRC graphs on for interesting comparisons. Lots of speakers have, lets say, unusual concepts of flat. Thiel has no dip in the presence region that many do and thus come off bright by comparision."

I do...Lot's of speakers out there that aren't very good. and Remember I like the CS2.4 something I seem to not get credit for, that is a speaker that does it all very well. You will notice that the only instructions the NRC received from Thiel was the height at which the speaker should be measured. The CS2.4 is a complete design.

The CS2.4 enhances the Thiel reputation, the CS2.3 never was deserving of it and now never will be.

We have been over the Thiel issue before so I'll try to limit my comments to CD quality, as yours seems to be a minority opinion on the 2.3. I have read about 8-10 magazine/web writeups and it has been highly praised. Anyway, many classical CDs tend to be a bit bright as the mics are placed quite close and higher up than your ears would be in a concert hall. Thus, more treble is recorded than you would hear unless you sit on stage. Too many piano discs have the mic stuck inside the body of the instrument. You don't think that alters the sound compared to real life? Sit next to a violon being played and it can drill your ears in, but it may sound great farther away, as intended. I don't listen to much popular music but I understand that vocals are routinely "punched up" to pop out on the lesser speakers most of the public use. The fact that as many CDs sound as good as they do is amazing.

"I have read about 8-10 magazine/web writeups and it has been highly praised."

Name one of those media outlets that ever said anything negative about any Thiel speaker or any product they reviewed.
Bunkeromantik - aren't you the guy who asked me about my SimAudio W5 with my Thiels CS2.3? I can't speak for your listening room but in my room there is definitely a large suckout at about 3-4khz, the presence region. But the suckout is not as awful as the Stereophile measurements would suggest. This is according to the measurements taken from my Tact RCS. I've made a lot of changes to my system to accomodate some of the weaknesses I percieved in my system. The Tact RCS smoothed out the in-room response, correcting some lumpiness in the bass and filling in the suckout at 3-4khz. Changing my source transport gave me all the dynamic range I can stand. Changing my preamp gave me all the speed, tone, and fullness of sound that I desired. Now the sound is sometimes even a little fuller than I prefer but with all the top end extension and air than I require. Did I mention that my system can make cymbals shimmer like nobody's business.

A couple years ago I started a agon thread 'speakers that sounds like thiels on steroids' because I wanted a speaker with more dynamic range. Well I can happily say that I found that speaker and it is the same Thiels that I always had. My point is that there really was nothing seriously wrong with my speakers. All the changes made to my system were in other parts of the chain and the Thiels transparency rewarded my efforts by by letting the music shine through.

The only thing my system can't do yet is truthfully reproduce a drum kit. That is next when I add Thiel's subwoofer system.

Bunkeromantik - I think you are already on the right track in upgrading your components. It isn't clear that a suckout exists in your system. But if it is then it may still be there in the cs2.4's. I think the suckout is because of the mechanical crossover thiel uses in their midrange. I would strongly suggest Tact RCS or a similar product. It'll be less expensive than a new pair of speakers and more effective too.
"Name one of those media outlets that ever said anything negative about any Thiel speaker or any product they reviewed."

Oh come on. While reviews seldom trash a product you can tell when they really like a product vs just saying it is pretty good. The Thiel CS 2.3 reviews have been raves and some even mention the tendancy toward brightness and need for great care in setup. We are getting no where. You hate the speaker and loads of people don't. Let's move on.

Cinematic Systems, could you describe the measurement technique used to find that "the CS2.3's are +10dB by the time they get to 20khz and +15 to 18 dB from 1 khz depending on the individual speaker" ? Were these your personal findings, etc.?
McTeague the question is again, should I upgrade? HELL YES!, just like the last thread. Defend your choice all you want,

Let's not forget the 100 or so people I witnessed laughing or giving me that look like they stepped in something after listening to the CS2.3. Actually most people hated that speaker and having to demo it hundreds of times over three years and moving it around to get it to "sound right". You represent the miniscule minority that bought the CS2.3.

Bufus, the measurements were done properly no worries, the speaker has a peak in the treble, this was constantly addressed by Thiel in the development of the concentric driver. Some upgrades were not announced or offerred as such. Funny thing is none of you guys ever measured the speaker so its not like you have data to the contrary just some supposition that I did something wrong. Its a bad speaker with many problems, CS2.4 corrects them all. My whole point buyer beware.
Mr systems,

Now that you have switched to calling me by my last name I guess you are irked. My point has always been that your experience is the one that seems out of step. I HAVE measured mine and do not have the peaks you suggest. Perhaps only me, 6 or 7 reviewers and most of the people posting to audioreview managed to get the only good versions of the 2.3 and all yours were defective. I do not deny your tests, just maintain that you seem to be the odd man out here. Check Thiel's site and lookup the online reviews. Many have charts and only Sterophile shows the climb in the treble, and their chart has different look than all the others they have. Where is the room averaged response with the blocky line?


Depending on when the review was done will determine the response, heck if your CS2.3's are new then some changes could have happened after I stopped selling Thiels to inch it closer to where the CS2.4 is.

But one constant was a -4/-5 dB dip at or around 1200hz-1500hz and a rise of +4-+5 db through the 4K range which is a near +10 swing. in a narrow range of frequencies.

Last time I measured the CS2.3 was 2000, so that left 2 more years for changes.

Plus you are discounting the negative reaction of many, many clients. They listen they tell me what they think. What about them? That has a great deal to do with my stance, they weren't always so diplomatic as reviewers.

Tim, I'm not upset, and I realize I'm out of step with common lore on the speaker. Item: 1117244877 Take a look at a speaker I built and how it measures. I'm just an amateur, weird guy out of step with the world. But just so there's no misunderstanding what my expectations are.

Yes sir, it's me. I will always be greatfull for your advices. Thanks to you I got SIM W5 and absoloutly love it. I will check out the TACT RCS.
I would like to hear from people who switched from 2.3 to 2.4. I listened to 2.4 in dealers room and it sounded different then my 2.3. But the whole equipment was different so I cannot say how they actually differ. If I got a chance to have them in-house I will tell here what I found.
Cinematic systems, what piece of equipment did you use to measure the speaker's response? What weighting did you use?
No weighting,

MLSSA, a computer program with B&K microphone and preamp

ETF with calibrated microphone and preamp

version 2.0 (not my system)

Version 4.7? (my system)

My speakers measured on Version 5.9 calibrated microphone.
IMHO - It seems to me some people are missing the point of the thread. Cinematic systems is trying to create a scientific review to explain his side of a open ended question. I can write a hundred reasons why Cabernet Sauvignon is a better buy than white zinfandel but if someone likes white zin my recomendation is wrong for that person. Bunkeromantik is asking for an opinion not a thesis. I think we all agree Thiel speakers are a exceptional product. I think we all agree that the 2.4s are an upgrade to the 2.3s. Thiel doesn't produce a new model without significant justifiable improvements (the 3.6s long run shows that). Where the gray area is is in the amount of improvement vs. the cost. Only Bunkeromantik's ear can make that call. Bunkeromantik, with the reasonable prices I have seen on Audiogon for 3.6s and higher Thiel models, I would recommend upgrading past the 2.4s(if possible).
A pair of Thiel 5i's just went for 3K.That was the asking price anyway.What a steal!
I heard the 2.4's at Thiel Audio last year.
They are a great sounding speaker.

Cinematic-Why don't you post your reference system on AudiogoN instead of your "bedroom system" Seems strange to me.

Actually if you go to the item link below you can atleast see my speakers ATC SCM150, but alas I won't have a surround system till May when I move to my new place. So I'm short 5 channels right now. But I'm chomping at the bit to get My 7 Eton 11.2 AXM's built. Going to be a wicked system. I hate having to put "I'm a dealer" everytime I talk about my system.

I am upgrading My bedroom speaker to a sub satellite system using Morel/Peerless drivers. I'm in the process of building those no photos.

Item: 1117244877 , the third picture.

The little speakers on stands were custom made for my brothers theater and the big black speakers are custom made ATC SCM150's.

Not shown, ATC SCA2 and Meridian G08.

There you go
Cinematic-Your Fibre 18.2's look very well made.
Do they sound as good as they look?
How do they stack up against a similary sized/priced ATC?
Thank you for 'straightening' me out...dude :~)
Thanks David,

They are pretty good, the square cabinet hurts the off axis response a little. They are warm sounding and maybe a little subdued in dynamics when not coupled to a subwoofer. My friend has the upgraded version with rounded baffles and grills and the Vifa Concentric tweeter which fixes many of the little details in the off axis performance and clarity in the highs. But these speakers are flat to 50 hz where I intended to pass the low frequencies off to a subwoofer. They have served me well. I have sold to 3 (5 speakers ea.) sets of these speakers to clients. And no complaints, infact 2 of them have upgraded to complete active systems.

I already sold the "upgraded ones" I mention in my System profile. These are the one pair I didn't upgrade.

There's a reason I carry the speakers I carry for Cinematic Systems. They are much better than what I can build myself considering the price. I figure since I'm a part time amateur, the pro's should be able to be better than me by a good margin. That's how I determine if I'm going to carry a speaker line or not.
I was fortunate enough to demo the current version of the 2.3s and 2.4s in my dedicated listening room for over a week. I am using a ML 27.5 amp which is rated at 100WPC.

I found the Thiel 2.4s rounded off the sharp highs (maintaining accuracy) that the 2.3's had a reputation of. The bass goes deeper and remains tighter than the 2.3 as well. I would say that they still sit on the analytical side of the fence, but not to the same degree as they once did.

Good electronics are still a must.

The 2.4s are also easier to drive than the 2.3. The impedance curve is much nicer on you amp.

My overall assessment I think could be described as, the 2.4 did everything as least well as the 2.3, although on some material the 2.4s were better. The 2.3s never surpassed the 2.4's on any recording that I listened to. I ended up choosing the 2.4 over a nicely priced pair of 2.3's.

I did find that placement of the 2.4s was fussier than the 2.3s. It took me a while to dial in the 2.4s. The 2.3s didn't take as long.
Now that is a decent comment. Thank You a lot. You cleared a lot in my mind.
In my recent set-up I find my 2.3 to be acurate with no sharpness to it. Sometimes I even felt I would like more top-end energy but I think I found it with introduction of new IC. It is still burnig-in so I reserve futher comment.

2.4 is much easier to drive compare to 2.3 that is obvious. Don't you think the sharper highs you noticed on 2.3 could be an indication of not enough juice out of your amp? I am using powerhouse amplifier (SIM W5 LE) and prior to the new IC I could use more sparkle on top. Plese do not get me wrong I am not highs freak and I hate when it is bright - I had my 2.3 bright on some set-ups and it was frustrating.
Some reviews point that 2.4 are a little bass-shy in terms of quantity. Would you say 2.4 produce more or less bass compare to 2.3? I understand you prefer 2.4 bass over 2.3 it terms of quality. But that could also be amp-related. I couldn't think of my 2.3 bass to be any tighter without losing body and mass. I still think it could be more developed esspecially in mid bass. Lower bass is stunning.

You might be right on the amp power. I have not yet tried a more powerful amp. I am hoping to upgrade that piece some time this year. I also feel it might have to do with my room being somewhat narrow (12 feet), I was forced to use some toe-in which causes the tweeter to beam a little, and I think the 2.4s were a little easier to handle than the 2.3s. If you are pointing straight ahead like Thiel recommends, this may not be an issue for you.

I found that the bass wasn't more, but it went down deeper than the 2.3's, and I think the overall all bass region was more controled (not that I thought the 2.3 was sloppy by any means). I actually had to pull my speakers away from the back wall a little more to calm the bass down. I can't imagine that the 2.4 can't produce enough bass unless you are a big pipe organ fan, or you have a large room to fill.

The biggest thing I found with both speakers is that changing the placement, even slightly, can have a big impact on sound. If you are missing some sparkle, then try a slight toe-in using small adjustments at a time. One other thing that I forgot to mention is that I think it is an absolute must that your listening position is at least 8 feet away from the speakers on the 2.4's. I don't remember if that was the case on the 2.3s
If You will search for a new amp if possible audition SIM AUDIO W5. It did a tremendous job in controlling low end and filling-in the midrange of my 2.3. It does wonders on dynamics and palpability of the sound. To this day I am not sure wich I love more my Thiels or the SIM. Thankfully I got both. One of Audiogoners made me buy it and I am very greatfull to him. Just check it out, pal.
Sorry to be so late adding my comments, I don't peruse the forums like I used to. The thread I started 12/03 about this is still there but not found when searching the archives. I've owned late-model 2.3s for a couple years now, and compared them at length to 2.4s with very good equipment at a store when I posted these observations, and still stand by them:

I've heard 2.4s a number of times since, but my listening impressions between 2.3 and 2.4 have remained clear to me. I'm sure by now the original poster has kept his 2.3s or moved on, but I have a couple comments. No doubt if I had 2.4s at home for awhile I'd pick up on even more subtle differences (hopefully improvements).

Swklein's initial post effectively said in a couple sentences what took me a couple paragraphs in my original post. The 2.4s clearly have more warmth and openness through the mids which does move it slightly closer to a more-relaxed Vandersteen (and others) sound while retaining the best aspects of Thiel's analytical side too. I also found the 2.4 to have a bit more bass energy, but no less lower-treble forwardness, and even more top-end sizzle. Also they're a bit easier to drive, as has been pointed out, but I'm fortunate to have a high-current amp with plenty of guts into difficult loads (ie my 2.3s), and ditto for the hardware I had at my disposal when comparing the two models. I think some of Dewinkle's observations are due to his amp and room limitations.

Cinematic_systems throws in a wrench. I have no reason to discount his frustrating experiences trying to mate these speakers to his rooms and electronics, I'm sure he spent all the time he suggests trying his best to make them work. OTOH, tons of 2.3s were sold from dealer showrooms worldwide, weren't they Thiel's most popular speaker ever, at least then? And while he gives full credit to the 2.4, I just have never heard such a remarkable difference between the two such that the "2.3 is a bad speaker with many problems and the 2.4 corrects them all".

I've measured my 2.3s in my room (admittedly near-ideal setup and acoustics) several ways in lots of positions and don't find a boosted top-end or big crossover suckouts, but it does show a certain upper mids forwardness, just as I also heard on the 2.4s, and what gives all Thiels their 'bright' reputation. Good electronics are essential, though I haven't played with speaker cables or interconnects (yet?) to try and alter the sound. My 2.3s are many feet away from any walls, 8' apart and 9' from my ideal listening position: those with narrower, brighter rooms may have more setup problems than I've encountered, but my guess this would apply equally to 2.4 as it's at least as 'bright' to my ears. Both speakers have very little radiating area for their price/size, a 6.5" (cone-diameter) woofer and 2.5" mid, combined with the shallow crossover slopes and huge number of crossover components I feel limit their ultimate SPLs and microdynamic transparency more than say a B&W 804 with larger cones and steeper slopes. But what sonic tradeoffs for time/phase alignment?

I've read all the reviews of both speakers and we all know you gotta try and read between the lines. My take is the 2.4 is better received by the press as a whole than the 2.3, despite its having purely evolutionary tweaks on the same design. But as cinematic_systems points out, in 5yrs technology marches on and lotsa small judicious improvements can change a speaker's character substantially for the better.

Which comes down to the same thing Buda offers. Is the 2.4 worth upgrading over the 2.3? Yes, I feel it's definitely a better speaker that offers more bass, fills in the lower mids, has a more transparent midrange presentation, but doesn't alter the accept-it-or-hate-it upper mids forwardness, and is at least as hot on top as the 2.3. The 2.4 does some significant things a bit better than the 2.3, the 2.3 probably does nothing better than the 2.4, but I think they equally share many of the same attributes and deficits. But let's face it, the speakers sound very similar to each other versus either Thiel to any other brand of speaker.

I haven't figured out how much *I'd* be willing to pay for the upgrade on the used market as I'm off the big-ticket merry-go-round for awhile. If the 2.4s were traded straight up for my 2.3s I'd sure do it, but knowing that there's always better audio components out there, and I remain satisfied with my 2.3's presentation, I'll leave well enough alone for now.

Sorry, I guess I'm getting sucked back into the hifi fray again :-O
"Both speakers have very little radiating area for their price/size, a 6.5" (cone-diameter) woofer and 2.5" mid, combined with the shallow crossover slopes and huge number of crossover components I feel limit their ultimate SPLs and microdynamic transparency"

Yes, my impression is the CS2.4 handles power better than the CS2.3's and is simply better behaved. Which is why I felt I could enjoy it more.

I want to qualify my early comments too, with this adendum (sp -1)

The last long term exposure to the CS2.3 was 2001, but 2000 production models, it is very if not certainly likely that Thiel has continued to improve their coaxial driver as they had from 1998 to 2001 and newer versions of the CS2.3 like a 2002 production model may very well be a fraction different from the CS2.4. So the variations may very well be a function of production time and version. Thiel will continue to improve their products (their right reserved) even if they don't change the model or version number.

Having not heard a CS2.3 for several years on a daily basis, hearing the CS2.4, it was a relief to hear a speaker I could actually listen too. Which is what struck me so black and white on this matter.
I actually had a pair of 2.4s in my room to see if they were much better than my 2.3s(with upgraded drivers). While the 2.4 had a bit better bass they were nearly identical. The dealer insisted on coming over as he remembers the 2.3s as being no where close to the 2.4s. I sat there using the A/B switch from my NAD remote, the speakers were side by side, not the best arrangement but both were equally handicapped, and he was gobsmacked. At one point he said "now that's the 2.4, right?" to which I replied..uh, no, that's the 2.3. Once I pointed out it was easy to tell them apart as the 2.4 was a bit more efficient and, thus, a little louder he started making comments such as "more liquid" for the 2.4. He did, however, agree that they were REALLY close and that I must have a special pair of 2.3s! Right. Anyway, I finally did come across a pair I like better, the Linkwitz Orions so will finally be moving away from Thiel but I will never say a bad thing about them. Great speaker and great company.

Tim McTeague
My Thiel 2.3's were early model, and I know that there was one major change early in the life of that model: an upgrade to the midrange driver that was reputed to smooth out the upper midrange. I can't say for certain that I ever heard a 2.3 with that upgrade.

So, the difference between 2.3 and 2.4 MAY depend substantially on whether the 2.3 has the newer midrange driver.

2.3s started production in early '98 and the woofer was changed after about 400 units were built. The coax driver was changed (small tweaks to reduce resonances and a peak) sometime in 2000, along with a crossover modification to accomodate this. Both these changes are user-upgradeable, though many (most?) of the 2.3s out there came from the factory this way.

The 2.4 coax is quite a bit different than either the original or newer 2.3 coax (or PCS coax for that matter): more open basket due to a much smaller, more powerful magnet structure yielding more power handling and the more open-sounding mids. Apparently more attention paid to further reducing cone resonances, though it looks identical to the 2.3 from outside. Thiel won't allow any 2.4 coaxes to be installed in 2.3s, the 2.4 crossover is set up specifically for the 2.4's new drivers. Though one would think a 2.4 woofer, coax and crossover in a 2.3 would get you 90% of the way to a 2.4...
As I typed, I had both Thiels, side by side, in my room and the 2.3 is already 90% of a 2.4. Maybe 98%. Few people really do side by side listening. We all know how erratic sound memory can be when the element of time is involved.

Tim McTeague
Tim, from my original post with the 2.3 and 2.4 side-by-side for hours I suggested they *were* very close, with the 2.4 doing just a couple things a bit better. Depending on what's important to you and the subjective metric of "%", yeah, the 2.3 is 90+% of the 2.4.

My last post was saying that of the 2.4's ~10% improvement, you might be able to make up 90% of that 10% difference with 2.4 drivers and xover in a 2.3, the balance being their tweaks to the oval passive radiator tuning and enclosure (external & internal).

Like yourself though, I'll probably move to an entirely different speaker brand eventually when (if) I feel a need to replace the 2.3s...
Tim, care to tell us a little about the Linkwitz Orions?
In my own personal experience, side by side testing is sometimes not revealing of differences, unless you have first spent quite a bit of time listening to each of them on it's own. I don't know why. I assume it's because your ear somehow learns the character of each of the different speakers. It sounds like you have done that though.
Art, I agree with what you said, but in my case I was intimately familiar with my 2.3s. But not with the dealer's (excellent) room and equipment. As the 2.4 is so similar, it was the differences to the well-known 2.3 that stood out pretty clearly. No doubt if I replaced the 2.3s with 2.4s in my own room & equipment, I'd hear a lot more of the subtleties between the two. But that wasn't an option at the time and I just don't think the differences are much more significant than what I heard in a different space.
Side by side is the only reliable way to tell minor differences. Our ability to remember subtle changes in sound is poor to say the least. Memory does funny things and is more affected by other stimuli than most would admit. Tests have shown people tend to find differences when no component had actually been switched. As for the Orions, I am still putting them together. The cabinetmaker left out the screws for the drivers and some pilot holes were misplaced and others missing altogether. Part and parcel with DIY stuff I guess.
Did anyone took the mid/tweeter driver out of the CS2.4? I am just curious if Thiel really make the drivers themselves as it is not viable to manufacture a relative small number themselves or, what I suspect, Thiel is installing a(n) (OEM) version of a known brand like SEAS or Dynaudio in the CS2.4

The rationale behind it is to get a cheap(er) CS2.3 and mount CS2.4 mid/tweeters.
There is a good reason that Thiel wouldnt sell the CS2.4 coaxial drivers by themselves or put them in a CS2.3
Thiel used to use outsourced drivers that were modified to Thiels specs. They've been using their own drivers for some time now. The most recent ones, such as those used on the 3.7's are clearly very different than those used by others.
That 2.4 mid/high driver is very different from others manufactured by the company. There is no electronic crossover but instead a physical transfer is designed between the two drivers (common coil used) based on the polymer that couples/uncouples these two portions of the driver depending on the frequency.

This is a superb forward thinking design with excellent coherence and minimal phase shift in the transfer region.
Excellent discussion- guys. I will add that the CS 2.4 gets timbre "right".
I do not know if the older models exact this difference? Happy Listening!
I own 2.4's. The only real issue I have is the "kick drum range". It doesn't do that super well like it does the rest of the range. I have them paired with it an REL sub. Which fills out the lower range well but doesn't really give you the "thwack" of the kick drum. 

Other than that, to make them work you need high current amps and good sources. To that end I have a VPI Prime with Parasonnd JC3+ and Dynavector 20x2 lo mc cart going to a BAT pre and Parasound A21 amp. 

The speakers are transparent with air, and 3D as well. 
Good to see you-last_lemming.

Thanks! for sharing your thoughts. Keep me posted as you go to a B.A.T. pre-amp. I cannot suggest enough a  REL subwoofer as well.