Thiel Owners

thannotopis321

I remember that the Aragon amps sounded very good with my Thiel speakers, too.

The ARC amps were just "quite good" with the stock Russian tubes. I really splurged, and bought 16 (8 per channel) NOS (and really new, never used) Tungsol 6550 tubes, USA made in the 1950s, for $175 each. And, WOW, they sound like different amps now, TOTALLY worth almost doubling their cost to me. Now they are indeed "killer" to my ears. Surprisingly, my CS3.5s don’t sound much different than my CS3.7s, with these amps. There is a consistency to the sound of all Thiel speakers that is truly impressive. Most speaker manufacturers have more variety in how their different speaker models have sounded. B&W is a prime example of this.

Tom Thiel and Harrylavo:

Hello Tom, this is my first post in this forum. I have been posting only in the SteveHoffman.tv forums for the past few years. Today, I just found out that you are here. So, here I am too.

During the decades of owning my Thiel CS3.5 speakers, I have tried hundreds of amplifiers with them, and can remember my sonic result with just about all of them. Adcom NEVER sounded good with Thiels, no matter how much power. Together they sound bland, lacking in dynamics, and electronic (not natural). The Amber Series-70 was an excellent combination in every way, one of the best I ever heard. It had actually only about 60 wpc (but it was famous for a having a VERY large power transformer and capability to deliver high current to low impedance or wildly varying impedance speakers). The other excellent matches were Classe DR series amps, all Mark Levinsons, and all Krells. But when I started hearing tube amps with Thiels, I never went back to solid state with them. Even very low power tube amps sound REALLY great with Thiel CS3.5. In fact, I never found one tube amp that didn’t sound great with them. Even a 6 wpc SET amp from AES was awesome. Now I am using Audio Research Classic 120 mono amps with my CS3.7, and it is an impressive match with the CS3.5 also. I think $3000 for a pair of these amps is a bargain. With my 3.5s, I am still using my MFA (Moore Franklyn) M-120 amps in triode mode, 60 wpc. When listeners hear this system, they cannot believe that I have been listening to such great sound for about 30 years. Newer, comparable amps would be from Bruce Moore Design, but are expensive. So my advice is that just about any stereo tube amp, with at least 60 wpc, into the CS3.5 is pure heaven. With solid state, you need to be more careful to audition in advance, and don’t go lower than 100 wpc in power.

--Warren (AKA "Sandy")

Even I suspected that I was crazy to spend as much on power tubes as on the entire purchase of the amps. Particularly since, as ARC’s only amps ever made for full triode operation, these amps make a measly 120 wpc with the 16 power tubes. All other ARC amps that have ever used 16 tubes, before or after the Classic 120s, made/make at least 200 wpc. So these are VERY special amps and VERY special tubes, and I am happy to be hearing them, despite their total cost.

To make my tubes even more interesting, these Tungsols came from a big box of military supply, in which ALL the tubes were matched (some 60+ years ago), then stored truly NOS ever since. So my set is a matched "sex-teen-tet"... well I also bought 4 spares, so a matched "twenty-tet".

Yeah, I think I was crazy. I can tell you this: I never play background music anymore, with these tubes burning. The system either has my full attention or is off. I don’t answer the phone, my wife knows to ignore me (because I will her), and even the dog won’t come in the listening room anymore when I am listening.

By the way, my preamp is a $20,000 Audio Note M6 with phono, and my cables are Cardas Clear Reflection. So the ARC amps and the Thiel speakers are hitting WAY above their current used value would suggest.

I have something to add about having owned Thiel CS3.5 speakers for over 30 years. I have quite a few friends that remember my system with these speakers as being the best system that they every heard anywhere, including CES and other audio shows. One of my friends finally declared that there is "no way a system 30 years old can still have sounded better than I have ever heard since. I must be building it up in my mind, like a fish story".

Well, about 2 years ago, when my wife bought an extra house for us (I mean that we didn’t move in, she just bought it for later), I decided to set-up in its living room the EXACT same system that I had dismantled about 10 years earlier.
The speakers were in storage, the Cardas Hexlink Golden 5C interconnects were here, the CAT preamp was there, and may favorite tube mono amplifiers for the Thiels were also in storage. Once all put back together, I invited a few of these old friends over to hear the "famous" Thiel system again. We all agreed, it was STILL the best system we have ever heard. Wow, with carefully chosen associated equipment, the CS3.5 speakers sound like magic. They make magic, with their immaculate imaging, impressive dynamic contrasts (both micro and macro), super low and accurate bass (with the EQ), and reproduction of the natural timbre of real acoustic instruments. My new CS3.7 speakers are not significantly better in these particular qualities. As a whole, they sound quite similar. I doubt that any 2.x speakers can beat the CS3.5, but I have two pair of 2.x now, that I have not heard yet, so I will find out soon.

I know that some of you are thinking, including Tom, "No way his 30 years old CS3.5 speakers can sound as good as 3.7 speakers with Audio Research Classic 120 amps and a $20000 Audio Note preamp." Well just don’t underestimate the benefit of 20 years working on a system, carefully comparing amplifiers and preamplifiers, using current VERY high-end cartridges (e.g. Koestu, Benz Ebony LP, ZYX, Shelter), and choosing the best sonic match for every single cable in the system. Plus experimenting with AC conditioning, room acoustic treatments, and speaker positioning (in inch increments). Also, since the 3.5s were moved to a bedroom and the 3.7s are back in the living room, I have started the intense tweeking process with them, like I did with the 3.5s.

tomthiel

Hello Tom, this is Sandy. Your explanation of the single most important limitation with the 3.5 explains two questions that have been bothering me for the past few years.

1) I NEVER had any problem with coping with dynamics, when the CS3.5 speakers were in my primary audio system (well, my ONLY audio system at that time). But then again, in those days, my 3.5s were in a very small dedicated listening room, only 10’ x 11’. And, that was in the days before CD was invented. So, more recent reports, claiming that newer Thiels are "better" always caused my disbelief... because how can perfection be improved upon! Well, you answered that: I didn’t have a situation that pushed their limits.

2) I heard a rumor that the 3.5’s midrange can be easily blown, from a burned voice coil, due to the wide bandwidth it has to deal with, imposed by the gentle crossover slopes. But I NEVER had a problem. That is, until I moved to a much larger room AND entered the era of CD. Since then, yes I did blow a midrange and I had to start being careful about volume. So, because those midranges are impossible to repair or replace, I had to buy a whole second pair, just to scavenger a midrange. And I have been hoarding 2nd and 3rd pairs ever since. Luckily, 3.5s are absurdly cheap now, particularly in poor cosmetic condition. But having these extras as spares takes up a lot of space!

I am SOOOO glad I found you here, so I can hear (read) more of your Thiel comments.

-- Warren (aka "Sandy"), Audio Note (uk) dealer, www.TheAudioHome.com

Oh, by the way, that first pair of Thiel speakers I ever heard, at Havens & Hardesty, was the O3a, predecessor to the CS3, CS3.5, CS3.6, etc. I wonder what year that was, probably early 1980s.

Thiel was as-yet off the audiophile map at that time, having just received a review in either TAS or Stereophile, which of course was extremely complimentary, particularly about the O3a's amazing imaging, including from way outside the speakers' locations. Also about "depth", imaging from way beyond the back wall. Imaging and depth were all the rage at that time, not emphasized so much now-a-days.

tomthiel

The first time I ever heard a Thiel speaker was at Havens and Hardesty in Seal Beach, CA. Somebody from Thiel was there, just trying to convince Mr. Hardesty to carry them, which they did, soon after. I was blown away by the specificity of imaging, even from outside the speakers, and the presentation of depth from far behind the speakers . No speaker ever did that for me before. I wanted a pair, but I was a penny-less college student, so I bought a pair used. When the 3.0 came out, I never had an interest in upgrading, based on hearing them at CES. But hearing the 3.5, and reading about it in the magazines, sold me immediately, and I bought a pair new (from Havens and Hardesty).

Now, besides my new CS3.7 and subwoofer, I have 3 pairs of CS3.5 in storage (originals still have the blown midrange, the extra 2 were for spare midranges but they are too nice to take apart), two pair of O3a (one pair have never been out of service since I bought them used as current models), two pair of O2 (they need woofer re-foam, so I’ve never heard them), and two pair of CS2.x (also have not listened to them yet). The older CS2.x I intended to use for rear channel speakers maybe, and the newer CS2.x I only bought very recently to participate in Tom’s upgrade kit project. So I still have a lot to experience with my older Thiels. The O3a, in my opinion, are very close in sound to the CS3.5, particularly the spectacular imaging and low-level detail retrieval. I have never heard CS3.0 or CS3.6, except at CES, and I didn’t think they ever really sounded great at a show, like they might have in a real home environment. For some reason, the CS3.5 always DID sound VERY good at CES, Chicago (Blackstone Hotel) and Las Vegas (Sahara and Riviera).

At CES, Jim and Kathy were never available for me to chat with, so I always spoke with Tom at the shows. Jim was somewhat uncomfortable just chatting in general, so he was always tucked away in the meeting rooms, and Kathy was always busy doing business in those rooms. When not so busy, she just never seemed to be approachable. But Tom was ALWAYS extremely warm and approachable.

Just so all of you know, Tom is a super warm and down-to-earth guy; as they say, the kind who you would really like to have a beer with. I perceived Jim as seriously introspective (as you might expect a genius to be), and Kathy just seemed all business, no fun. And then, after Tom stopped going to CES, there was Martin (I think was his name... or was his guitar a Martin?... anyway, he was a Tony Rice fan), who was also very nice to chat with. He worked for Thiel for a LONG time.

--Warren (AKA Sandy)

tomthiel

Oh yes, now I remember the HP review of the O3a. After I heard Thiels for the first time, at Havens and Hardesty, I stumbled upon that recent issue of TAS and read HP's review of them. What I remember most was that his choice of words described with amazing accuracy what I had heard. I have never read, before or after HP, another reviewer's words that so vividly described sound. It reinforced my excitement about the "image specificity" and "disappearance of the speakers' location" that he described. So, there were no speakers in the world that could satisfy me after that pair of experiences: hearing them and reading HP's description of them. Plus, the cabinet shape and wood finish was just gorgeous.

Luckily for me, a rich guy in Laguna Beach went througn speakers like I drink water, and he had the hots for "Kindel Phantom" speakers instead of his Thiel O3a, so they were almost brand new when I bought them from him. Of course now, we all know he was crazy, because Thiel speakers are still cherished by all of us here, whereas Kindel speakers are long forgotten by everyone.

I visited him a few more times after that. Soon after his Kindel speakers, he sold those for Spendor SP-1 speakers (another still HIGHLY remembered and GREAT speaker), but sold those also almost right away. He could simply never be satisfied. And to this day, I am greatly satisfied with the O3a that I bought from him, and still listening to them.

I would like to explain the basic principle behind Outriggers or spikes under the speakers, so that each of us can answer the question of "need" for ourselves. Basically, when a woofer’s motor structure (this means the magnet and voice coil) applies force to the cone, causing it to move in and out, the woofer itself has enough mass that an equal-and-opposite force is applied to the entire speaker cabinet. If the bottom of the speaker cabinet is not firmly coupled to the floor and rigidly stable, the speaker will rock in the opposite direction as the woofer, causing inaccurate sound from the woofer (primarily Doppler distortion). So we apply cone feet under the speaker, to stabilize it, and even better, puncture through the carpet to the floor itself. We are simply trying to make sure there is not even very slight cabinet motion possible, under the force of woofer motion.

Since Thiel speakers have a relatively small footprint compared to their height, it can be helpful for the cones to be situated farther apart than the depth and width of the cabinet. The Outriggers help in this regard, compared to simply adding cones under the speaker, due to their greater separation distance, as well as their firm attachment to the bottom of the speaker.

But, however you stabilize each speaker, if you cannot rock either one, and so they are firmly unable to move even the tiniest bit, then you have accomplished this "rigidly stable" condition, that I am claiming is so important to producing accurate bass. A well known TAS reviewer from the 70’s and 80’s, Enid Lumley, claimed she stabilized the speakers by hanging them from the ceiling with fishing line. She claimed that the weight of the speaker, and the long length of the line, did the trick, PLUS decoupled the speaker from the floor completely, so there was absolutely no interaction of vibrations in the floor with the speakers. I have noticed recently there is a growing number of audiophiles applying heavily damped, but not rigid, feet under speakers to accomplish this. This is a current "fad" that is growing in popularity. But that is another story, beyond this spike/Outriggers explanation.

By the way, Enid’s speakers were Magnepans, so their moving panels had lower mass, and therefore applied lower "equal and opposite" force on the cabinet, than cone woofers.

--Warren (aka "Sandy")

tomthiel

I am very excited you added that "sway effects" (your words) influence imaging of the higher frequencies. This makes so much sense that, in the words of a Thiel -- the ultimate name for speaker phase and time coherence and their effect on "image specificity" -- the speaker swaying from "equal-and-opposite motion from woofer motion" (my words), would have primarily this effect. Most speakers don't have a Thiel's capability for this level of imaging, whether they are swaying or not. So for most speakers, a flabby bass is the most obvious effect of not providing stable spikes to stabilize them.

I AM having fun, just reading and writing about Thiels, almost as much fun as listening to them!

--Warren (aka Sandy)

harrylavo

With Thiel CS3.5 speakers available now for only $400 or $500, I collect them for their drivers. I think using original drivers is the only way to keeping them sound as they should. One time, I bought a pair of CS3.5 on Ebay, and asked the seller to remove and send ONLY the tweeters and midranges.

The tweeters are stock items, which appear on ebay quite frequently. The midranges were custom made, so totally unavailable now. But they can be re-coned, although a burnt voice coil is not repairable.

The solutions are 1) use an amplifier that has plenty of extra power that you will never use (and will never clip from reaching its power limit) and 2) don’t ever play music loud enough that you hear some dynamic compression or distortion.

3) If you want to follow my advice, don’t play CDs anymore either, Just stick to analog. It sounds better, and it is peak-limited for the very same reason that Thiel CS3.5 like them better: phono cartrdiges have a mechanical excursion limit as do speakers. No strike this suggestion, I was just using this opportunity to push records over CDs. Answer #2 should suffice, no matter what format you play.

tomthiel

Would you mind telling us about each 2-series model, what the differences are, and why you chose one over the others to design your first kit?

Also, why would anyone want a CS2.x, when (to my thinking) a CS3.x model is bigger and better, for about the same used prices? I only ask because I am a fan of the O3a, CS3.5 and CS3.7, but never even heard any 2.x yet (except at a CES).

--Sandy

tomthiel

Thank you very much for your synopsis of the 2.x models: their differences among themselves, benefits compared to the 3.x, your preferences and history with them, and why so many people like them.

Most of the followers of this thread don’t realize that I have known Tom from the days of the O3a, more than 30 years, from CES in both Las Vegas and Chicago. The Thiel room was one of my favorite every time, and Tom one of my favorite people to chat with. I have kept occasional contact with him ever since then, just to talk about the speakers. When he told me about his preference for the 2.x models, I could not resist collecting a CS2.0 and CS2.2 for myself, even though I still have never set them up to hear them. I have just been too enthralled with my O3a, CS3.5 and CS3.7, thinking I would miss them TOO MUCH if I moved them out to try the smaller ones.

Well, about 7 years ago, I became the exclusive dealer for Audio Note (UK) in the Los Angeles area. One of the Thiels had to go into storage to make room for a demo pair of AN/E speakers ($12,000/pair), and now I love them too. But then finally, when I moved back the CS3.5 into my primary listening room, my friends and I were amazed. What we all remembered as about the best sound we had ever heard (my Thiel CS3.5 system) was STILL among the VERY best we’ve ever heard. It is truly amazing that after all these years of my ownership, 20+ year old speakers demonstrate that the unique goals and successes of Jim Thiel still provide state-of-the-art sound, in these very specific aspects: imaging specificity, sound stage size, depth, resolution of subtle details, and presentation of very fine timbre and texture that approach the sound of truly live instruments and voices. The 30+ year old O3a, provide these magical characteristics as well. Since the CS3.5 proved themselves again, I have not moved AN speakers back into that room since. I bought a pair of CS3.7 speakers to put there, the CS3.5 are back in storage, and AN speakers populate the other rooms in my homes and retail audio salon. The Thiel O3a have never moved, by the way, and still sound awesome in my parents’ living room, where I have listened to them from the time they were current models. Yeah, that was when I was a college student, still living there.

Now, because of this thread, and all the love I have read about for the 2.x speakers, I have my CS2.0 pair (piano black) in the hallway, just about ready to insert them into one of my listening rooms, for the first time. My CS2.2 pair are DEFINITELY going to get the full Tom Thiel update treatment, and I will not be surprised if they take a permanent place in my life, along with the CS 3.7 in my living room that are not going anywhere either.

Harrylavo
 
I have a few extra tweeters and midranges for Thiel O3a and CS3.5. I hesitate to sell any of them, because they are so difficult to find. If you love these speakers and have a few spare parts, would YOU sell them? So, I think we should set some prices, within this group of Thiel cognoscenti, that are not unreasonable to those of us who need a few, but also fairly representative of their difficulty to obtain. I would rather not take full responsibility for the high prices I am about to suggest, but here they are:

O3a tweeter: $300 each
CS3.5 tweeter: $250 each
CS3.5 midrange: $400 each

These are not my asking prices (yet), but my proposal for a group decision, based on what we know about their rarity. And these prices are for guarenteed working units, with maybe a little wrinkle or two in the tweeter dome or midrange dust cover, but no damage to them and excellent cone and surround quality (which can be replaced).

Now, if there are other, cheaper sources for exactly the same tweeters, please let us all know. The Audax/Polydax tweeters were standard parts, used by a number of speaker manufacturers, but still getting more rare all the time. But there are variations in mounting plate dimensions and in ohm impedance, that we have to be careful to get right, and the guarentee not to be DOA that we have to confirm.

I wasn't clear about the O3a and CS3.5 tweeters in my post above. The Audax/Polydax was used in the O3a. They were plentiful, but they are getting more and more difficult to find. Spica and Snell are two manufacturers that used them also, and there were many more. The CS3.5 speakers used Dynaudio D28/2, 6 ohm, that were also mass produced and used for many years in many speakers, but very hard to find now.

I contacted ronkent to buy the stands, since I own a pair of 2.0 and a pair of 2.2. I am really looking forward to using them.

GENERAL QUESTION TO EVERYONE:

I bought a pair of genuine Thiel Outrigger stands, but the Ebay seller doesn't know what model they fit. The front two spikes are 13-3/4 inches apart, from center to center . Does anyone know which model(s) speaker they were made for?

Ronkent

I thought I bought the Sound Anchor stands. My Paypal shows that I did. Did you receive my payment?

Breyeagle and TomThiel

"I have a Thiel SS2.2 sub for the 2.7s, using a PX05 passive crossover, specifically tweaked for the 2.7s. It really helps..."

I use a Thiel SS2.2 sub for my CS3.7s, and a PX05. I can barely tell the difference with or without it. I am thinking it is supposed to work that way, because the 3.7 have fine bass without any subwoofer, so adding it just provides a little of what the 3.7 cannot do on their own.

Ronkent
______
I just looked at my Paypal history, and, yes indeed, I did pay you for the Sound Anchor stands on the 29th. But, I probably misled you by telling you about the Outriggers I bought on Ebay (without knowing which speakers they fit). And, I may not have advised you, after I paid, to look at your Paypal account to confirm. So, when convenient, please send them. My CS2.0 and CS2.2 are waiting for them.

Thielrules
________
Wow, I had hoped these Outriggers would fit my CS3.7. 13.75" seemed so small, and the CS3.7 look so big.

Does anyone else have Outriggers installed on ANY Thiel speaker? I would like to know the distance between the front 2 spikes (center to center), to know which models the pair I just bought will fit.

i too measured the distance on my3.7's: front 14"back 9.75, so it looks like thielrules was correct

Wow, this is great news, that these eBay find Outriggers are for my CS3.7 speakers. Thank you ronkent and thielrules !

The CJ Premier 12 amps are still expensive to buy used and expensive to re-tube when necessary. I would think a Premier 11 (the stereo version) would be a very nice substitute, and a fantastic amplifier to hear with the CS3.7s, also. I love CJ and I love ARC. I am currently using Audio Research Classic 120 mono amps with my CS3.7. They make a simply magical combination. But I am sure a CJ Premier 11 (or pair of Premier 12)  would be stiff competition.

Add a Classe DR8, DR9, DR-10 or DR-100 amplifier, and all is perfect in this world.

Oh, there's Santa now trying to stuff a pair of Thiel O3a speakers down my chimney. Oh how I have been hoping for another pair of these.

I have been having extensive telephone and email conversations with Tom about my love for certain models of Thiel (mostly the 3.5 and 3.7) and the one problem all have in common: a forward and agressive tendency in the upper midrange. As Tom experiments with solutions to apply to the cs2.x models, I have been duplicating his methods on my cs3.x models. He is tireless in his creativity, coming up with theories, testing them, aquiring variations of materials to compare, etc. And my Theil 3s have been exibiting the same benefits as he describes for the 2s

Tomthiel wrote:
"Just a thought. I suggest running the 3.5s wide open with no EQ. I remember the bass loading as critically damped, so it should approximate 12dB / octave. (But that's old memory) If you can match that rollout with a sub, the sub HF will operate in the directionality range, so 2 subs is better than 1. I for one am most in your progress."

Now we have here a subject very dear to my heart and experience. Both my Thiel O3a and CS3.5 had equalizers. I found the O3a to sound much better with a subwoofer crossed over EXACTLY  to the same curve as the EQ,  with no filter to the main speakers at all 

 The CS3.5's equalizer was a gigantic improvement, which I found to sound just as good as no eq at all. Never-the-less, there is the original Stereophile test still on the internet, which shows its EQ curve. Take out the equalizer, add one or two subwoofers, adjust their crossover frequency and slope to match that curve, and run the main Theils with no filter at all. This purist approach works and sounds like a charm. The 10"  woofers and main power amp are no longer taxed, so theoretically, distortion should be much less, and power handling much better.

thielrules wrote:
"Great posts. Just got lost with this statement. Not sure if there is a typo:
The CS3.5's equalizer was a gigantic improvement, which I found to sound just as good as no eq at all."
I meant to communicate that the CS3.5's equalizer was a gigantic sonic improvement over the O3a equalizer. Throwing away the O3a eq, and replacing it with subwoofers very much improved the sound of the O3a. But the CS3.5 crossover was so good, that using it didn't degrade the sound to my ears at all. So using it was "just as good" as not using it, in every sonic way except the obvious loss in low bass. And, except for power handling. So, for medium listening levels, I found no sonic reason to stop using the 3.5 equalizer. As Tom points out though, theoretically, using a subwoofer instead of the CS3.5 eq did have benefits to woofer excursion when playing louder. And when CDs came into being, playing louder became a problem for CS3.5 in many ways, not only the woofer excursion. Midranges and tweeters started to become over-driven too. In 20+ years of playing only records in a small bedroom through the CS3.5, I never had a problem. But when I started to use them again after 10 years of storage, well, then I was playing CDs too, and I had a much bigger room, so I burned out the midranges and noticed over-taxing the woofers.

To anyone who has used Thiel SS2 or SS3 subwoofer(s), either single or pair, with CS3.7 speakers, playing 2-channel music (not multi-channel video), I would like to ask for your advice. I currently listen to a pair of CS3.7 with a single SS2 in the middle of the CS3.7s, and now I feel like upgrading the subwoofer.

Shall I get another SS2, and run a pair of them, OR, shall I sell the SS2 and buy a SS3? Tom Thiel recommends a pair of SS2 over a SS3, for stereo music listening. But for me, that is starting to make my living room too full of speakers. I would rather trade-up in woofer size to a single SS3. The question is: What sonic benefits will I be likely to hear, comparing these two models, and will being bigger actually provide a sonic upgrade?

I don't usually play loud, bass heavy music. Maybe a Mahler Symphony could benefit from a little more bass power for the tympany drums, and I would like to hear Tool or Perfect Circle with lower and more powerful bass.

But what will I really hear, if I were to get the pair of 12" woofers (in a SS3) compared to the pair of 10" woofers (in the SS2) that I have now? According to the specs, the bigger woofers don't actually play lower, just louder.

Is there anyone reading this who has heard the difference between a SS2 subwoofer vs. a SS3 subwoofer?

I just don't want two of these big subwoofers in my living room. So for me, it looks like I will have to experiment for myself, 1 SS2 vs. 1 SS3. A pair of SS3 subwoofers would cost more than than the 3.7s are worth and has got to be overkill for just 2 channel music with CS3.7 speakers.

And, there is more to this integration of SS subwoofers to CS3.7 speakers. The Thiel passive crossover that is specifically configured for CS3.7 speakers was designed to only have a mono output. So one subwoofer was the original design concept. I would have to use Y adapters to split for two subwoofers, so they would both be mono anyway. 

It is a wonderful implementation because the crossover adds nothing in the signal path going  to the main speakers. The CS3.7s run full range. The crossover only senses the main speakers' signals from theor speaker cables, then transfers that information to the subwoofer to create ONLY the bass that 3.7s cannot reproduce alone. 

I do have a very nice Marchand active crossover I could use, but it seems to me that Thiel figured this all out, so why not use their passive crossover as intended?

Do you mean the 3.6 made it, but the 3.5 and 3.7 didn't? I strongly disagree with that. Every model in the 3 series was an innovative step forward in audiophile speaker history. The O3a was reviewed as unmatched in palpability of imaging. The CS3.5 was an O3a and 3.0 perfected, with an EQ that really brought full bass to a reasonbly priced speaker along with every audiophile quality fully provided.

The 3.6 sold a lot, and was a little better than the 3.5, but not so revolutionary in the history of audio. The 3.7 was the designer's testiment in revolution, execu5ion, performance, and accuracy including the most advanced custom driver designs ever yet marketed.

Regarding subwoofers for my CS3.7s, I am throwing caution into the wind, along with money  (gulp). I am buying two SS3 subs, and providing all the answers that I was hoping someone here could answer for me. The single SS2.2 I have now is on US Audiomart. But I suspect just adding another SS2.2 would have been the more conservative and equally satisfying route.

Tomthiel,
I agree that the CS3.6 is the model to start with. There were so many sold, and they have had so many accolades, positive reviews, and historical references, that people who own them just love them, and people who dont, do remember them. There is nothing in the used marketplace, even close to thier audiophile sound qualities for the prices they sell for now. So once you get a couple of thier sonic flaws eliminated, and the word gets out that Mr. Tom Thiel (and Rob of Coherent Source) offer mods for them, one of the USA's most famous speakers (ever) can become a truly collectable "classic" item.

I will stick with my Thiel 3.5s and 3.7s, driven by MFA and ARC 6550 tube amps (respectively) of course. BUT, I do have a BIG solid state amp, that I'm not using, just PERFECT for 3.6s: Classe DR-250, 250 wpc, and one of the sweetest big amps ever made.

... my problem with collecting too many models of Thiel speakers is that I am an Audio Note dealer. I need the space for demonstration of Audio Note products. What you are doing makes me wonder if there is a market for a used/modified Thiel dealer, here on the West Coast... hmmm.