Thiel Owners

Kenazfilan - about doubled up speakers for a bi-pole. Today I gave the configuration a whirl with 2 pairs of CS2.2s back to back. I am driving with a pair of Classe DR-9s and Benchmark AHB-2s both at 100 wpc/8, both bridged to mono. 4 amps into 4 speakers. The back pair is driven by a PS Stellar Pre with remote volume control to bring up the back channels to suit. At some point of about equal loudness back and front, the sound takes 3-D form and moves back between the speakers and wall. The effect is delightful and doesn't seem to harm image specificity. The bass especially becomes big and round and clean.

Since for the same volume level, each speaker is working half as hard, distortion is undoubtedly lower; and since the point source patterns are reinforcing each other front to back, a quasi hemispherical wave-front is being launched. For those who love omnidirectional launch, this is a wonderful way to get it.

For fun, I reversed polarity of the back speakers (a button on the PS remote) which produces a di-pole pattern like a planar speaker. Indeed I got the phasey boundary effect. Back in bi-pole, the speakers just sound bigger. I suspect my room might be easier than some for this use. My walls are soft with lots of diffusion and little in the way of standing waves because 2 walls are sonically fairly transparent into a much larger space. The coupled bass from 4 speakers allowed me to pull the speakers about 6' from the front wall to image like champs while maintaining plenty of bass.

Fun at the end of the day.

Jafant - The amps have been struggling for over a year and are indeed back home in fine fittle. The first tech made a mess of it, changing some cap values, mis-regulating and stressing some circuits. The second outfit came highly recommended as a warranty repair center for McIntosh among others. But their senior tech who could make sense of the mess was out for extended medical leave; and on return was buried in urgent backlog work. BUT, he went through both amps and got everything into synchronicity and they do sound good.

So, the DR-6 and 9s are like new, which is really quite good. My comparisons are the class A Benchmark AHB-2s and the Adcom GFA555II which I bought for entry level benchmarking. The Adcom really trails far behind in all audiophile ways, even though fairly well regarded in its time. The Classe and Benchmark are remarkably similar. I don't hear the "darkness" often attributed to the Classe. However I do hear a bit of gritty, dry hashiness in the Adcom (also repaired and tested as good.)
Now with 4 bridged amps / 8 channels available, I can make real time comparisons with 4 speakers under test - what joy. I'll get to some progress reports when the legal matters are finalized.

Jimihandtrix - I checked my CS1.6 tweeters and contacted Rob. The answer is that the CS1.6 tweeter is a custom-made driver from the ground up - there are no markings on it. The SEAS may physically fit, but that's where the similarity ends. Note that Thiel tweeters have very unusual requirements since they cross over low and with a shallow slope. A normal tweeter would not blend properly and would not last very long. Rob has good supply of moving system / rebuild kits, but I don't know his stock for whole drivers. Let us know what you find out.

Jimi - my apologies for confusion. I mis-remembered your model. I was speaking about the CS1.6 tweeter and you have CS1.2s for which I have no information. Please query Rob and let us know the outcome.

Rob says the CS1.2 tweeter is a SEAS 25TAC/GW H420 which is different from your SEAS 25TAF/G H400. Rob has rebuild kits, but no new drivers.

Bighempin - I have never seen that tweeter up close and personal. I believe that tweeter module comes out of the midrange mount. But that's risky business for a non-adept. I personally would try it in place. Your child's finger went in the center hole, so the failure geometry exists within that central area.

Bighempin - try masking tape or rig a vacuum cleaner to a small diameter tube to suck it out. I suggest a vacuum bypass in your tube, such as a hole you can cover with your finger to adjust vacuum pressure. Too much vacuum pressure could rupture the foil.

Andy 2 - Beetlemania and Holco (?) both reported improvements with internal wire. I have wire from StraightWire and Cardas in my comparison kit. However, the wire itself in the 2.4s is pretty high-end. It is 5-9s, high purity, low oxygen, long crystal, high polish 18 gauge solid in teflon jackets, precision twisted at 2.5 / inch. We first developed that wire in 1978 via our access to aerospace instrumentation solutions. The ITT aerospace 6-9s wire is no longer available, but current Thiel wire is as good as is available for its type.

Now, all that said, I believe there is possibly room for improvement via multi-gauge litzed bundling. Remember that a manufacturer occupying Thiel's cost-effective niche, can never afford state of the art, every decision is balanced for optimizing cost-effective balanced performance. But I will be substituting more sophisticated wire to compare its performance with stock.
I should note that in the development of the original 03 in 1977, wire purity for hookup and coils was paramount to getting listenable results from the phase coherent configuration, as I have elaborated earlier in this thread. I am very tuned in to wire, wire was in my purview during Thiel's first 20 years.

Yes! perhaps a fat milkshake straw for mouth suction.

Bighempin - I agree with Paul: in the pistonic range the same amount of air is moved, so the frequency response is not impacted very much. But there are further subtleties in my opinion. The shape of the compression wave coupled to the air will get turbulent as the frequencies approach the upper limit of the tweeter. I think it likely that the upper octave may become ragged with the crumpled dome.

Even though we, especially older male, listeners aren't supposed to hear above 15K (I'm out considerably lower than that), we somehow register anomalies in the upper ranges. I can hear the differences in various digital high-cut filter configurations, and all that stuff is supposed to be near or above 20kHz.

So, there may not be a "huge" difference, but then again, consider the effort we spend on getting quite small sonic improvements from our systems. The human ear-brain is a magnificent piece of work.

yyz - for your smallish space, you might also consider CS2.7s with the same coax. Lots of fans here. 

FYI: Thiel stained bare wood; if stained, the clearcoats would be on top of stain. If natural, the clear sealer and topcoats would be on bare wood. Refinishing is serious business. Are you experienced? You might consider some form of over-coat, like a pigmented topcoat, or translucent or opaque paint.

Keep us posted on their resurrection tour.

Jhouse - your speakers certainly do look altered, that's not a Thiel factory finish. The veneer looks to be Mahogany, which has a natural color in the salmon spectrum, which is generally stained some shade of red-brown. It looks like yours have been stripped, leaving some color in the scratches and pores. They could be refinished professionally or DIY with readily available finishing materials.
Thiel used very little Mahogany due to a combination of low demand and high hassle factor. There are many types of figure, grain, color and embedded expectations regarding Mahogany. Mahogany with its terminology and nuances is well understood in the world of fine furniture, but practically invisible in the world of audio. We would have needed an education and interface department to promote Mahogany, and chose instead to just offer it as an option on demand. Hard to guess why your cabinets got stripped.

I recommend getting the Benchmark AHB-2 into your auditioning mix if you can. Once I latched on to its clean, quiet capability, all the way to 1/2 ohm load, I have gotten hooked. Just sayin'

Ambroiseg - I believe the MCS-1 shares the coax with the CS2.3

Jafant - I catch all the posts, but try to limit my input to matters that matter. Rob has told me about the 2.3 x MCS coax, but third-party verification is always in order before anyone commits cash.

All - I think this lovely Autumn Friday in New Hampshire is a good time to share some recent developments. Several months ago, there were posts here about the Thiel midrange being shouty and harsh, and I pushed back to have set up scores of shows where that simply wasn't the case. I then began some soul-searching and tried to thank the poster off-line, but he had taken down his post. I want to thank him for a very productive period of my life. I apologize for not keeping your names straight, but time required to review the thread is more than I have. Here goes.

A tremendous amount of effort by Thiel aficionados goes into finding music, hardware, cables and room conditions to make their Thiels sing. We all do it. Thiel did it. Notice the Krell, Levinson, Pass and other amps that work, sometimes costing a large multiple of the speakers' price. I have musician friends who invest their lives in making their CD the best they can make it. And often on my reference system, built around CS2.2s, it can sound shouty and harsh, with midrange glare most evident when the music gets loud and complex. Same goes for rock, jazz and symphonies. We tend to blame the record producer because stellar CDs do sound good. Beetle (I think) asked here about that and I agreed with his assertion that Jim only valued good playback on excellent CDs, with no excuses for poorly engineered material.

Fair enough as far as it goes, but there is a lot of room between the few best examples and most of the remainder. In the past few months, I have listened to hundreds of (non audiophile) CDs, and don't like what I hear on most of them. I shifted the hypothetical responsibility away from the record producer and onto myself, and over a few weeks' time, I believe I am approaching a core paradigm shift. Whereas Jim's paradigm, shared by the whole Thiel team might be summarized: 'Complete Fidelity to the speaker's Input Signal', mine is developing more like: 'Translation of the artists' Dream'. I know that is fraught with philosophical burdens, but it also serves to take responsibility for a bigger slice of the pie. For instance, the new paradigm would have prohibited the low Thiel impedances because the Artists' Dream is to reach a populace which includes sub $$$$ amps. And so forth and so on.

A self-limiting assumption is that making the music more accessible will de facto reduce its accuracy. That will not be tolerated. I am proposing keeping present performance as a performance base line. After months of inner work, I have identified a sphere of great promise. And I appreciate those of you who are co-developing and testing with me, just as I appreciate Beetle and Holco and others off list who have co-developed crossover solutions. What we tried in Beetle's 2.4s achieves very  high-quality results, but the cost would be in three figures. And my verification here showed that something still seemed un-addressed. "It" became more evident with the (new to me) 3.6s from the hotrod garage. Despite their greater power, deeper bass and higher resolution than the 2.2s, there is also more upper midrange congestion, harshness, glare; more so on complex and loud music. My trusty stethoscope helped me find some sort of hash on the baffle flats that sounds a lot like the in-room "problem". Further dots were connected with the Vandersteen baffle discussion here, as well as my experiences with Dunlavy and Hales over the years. I am in the 4th iteration of baffle treatment which produces more, not less, inner detail and image size-height, while reducing that "glare" to where the large majority of music becomes enticing and enjoyable, rather than requiring excuses. I have trouble staying out of the studio to do my required work on other projects!
I am now assembling some kits for some of you to try, and feed back what you learn. I simply lack the upper frequency hearing, and face a shortage of appropriate listeners in my small village. Thanks guys. Present work addresses multiple cabinet aspects. I was part of 2.2 and 3.6 cabinet development, and proud of it. So it surprises me that so much work was left undone, due primarily to riding the wild bronco of manufacturing development and growth. The largest surprise to me is that for a fraction of the cost of crossover upgrades, we can make a qualitative improvement in the sonic presentation, in the musical assessibility. I know that's hard for insiders to believe and it puts a huge burden of proof on me;  I'm not asking you to believe anything. But, I am looking forward to user critique more than I ever have in the past.

Rob - to be clear, I meant to keep the 18 gauge going to the drivers, but you can increase the size between binding posts and XO panel.
Normal binding posts work. I'm saying to wrap the wire tightly before soldering. Let us all know when you find the perfect binding posts.

As a general observation, wire management is a big deal. Thiel buried long runs in channels routed into cabinet walls, sometimes used goo to attach to braces and generally made a spiral by rotating the driver as it goes into position. If you've had drivers out, you may have wire rattle.

Rob - I have done considerable work comparing and choosing caps and resistors, both with Beetle and consulting with folks at Thiel. I chose Mills MRA-12 resistors and ClarityCap CSA feed capacitors plus some CC customs for shunts. It is likely that large shunt caps will actually be electrolytics, which I have not chosen. I have not yet done the iterations re which caps matter enough for which price points, etc. But I have chosen candidate caps for each spot. Rob will only have the CC SAs which were CC's best at the time, for the series feeds. My legal status is not finalized for Thiel bankruptcy, so I can't now share schematics, etc. I consider Thiel coils world-class. Do not increase wire size in coils, since their resistance IS critical to the circuit performance. We learned that later CS2.4 XOs were made in China with inferior wire. Rob G might know the serial # watershed and might have Thiel coils. If so, I recommend upgrading at least the series feed coil in the midrange circuit. I am using custom coils from ERSE or Jensen as world-class equals. 

Regarding wire, as I've mentioned, that stock wire is world-class and carefully chosen. There is a widespread belief that sexier wire is better, and I concur in general. However, remember that increasing size will reduce resistance and that the wire resistance is part of the overall circuit design. Eventually I will measure the differences and compensate. For now, I suggest experimenting with different type (such as litz) at the same gauge, especially the long runs between XO and drivers. There is a spot which I perceive advantage without much alteration. Between the input terminals and the XO carries both direct and shunt signal and therefore acts as a choke point, both + and -. I like it thicker, but haven't measured it until I get to work on the XO as a whole.

There is room for improvement via better input terminals. I suggest tight mechanical connections before soldering. BTW, bare copper or silver on copper rocks. Gold isn't that great and brass is poor. CAIG Labs makes a conductive paste with cleaner-antioxidant in it. Keeps non-gold connections clean and conductive.  

Keep us posted.

Rob - a major part of the art is prioritizing the relative value of various aspects of the whole package. There is some experience on this forum - post your ideas and hope the guys will keep you out of trouble.

Excuse me - I mis-remembered Rob's model.

Prof, Andy and all - lotta stuff to chew here. We approached these matters a few months ago and got into trouble. I suggested that study was in order, not intending to disparage anyone - it is all quite subtle and worthy of more depth than we can enter here.
Prof: Toole's statement is false, and it carries lots of baggage. A: The basis of his mistake is that Jim candidly stated that it would be foolish for Thiel to approach the market with anything other than phase coherence. Note the difference in Toole's inference. B: It is nonsense. But Toole has a professional investment in the non-importance of phase coherence.
Andy: You state it well "Maybe our hearing is very tolerant". It is. It is more than that: hearing is a synthetic activity, we create the heard experience via very complex mechanisms. In a fiendish twist, the more sophisticated the listener, the less phase coherence matters, because s/he can create the heard experience despite the incoherent content.
As Andy alludes, the non-believers point to bandwidth limitations at 20kHz max to nullify the importance of waveform integrity. My study of audio and auditory neurology reveals that multiple parallel tracks decode the auditory stimulus, and the whole body is involved including the ears, mastoid process, sinus cavities, solar plexus and skin envelope - all working together to sense, decode and decide on the nature of incoming sound. The right and left ears transmit to different parts of the brain for different kinds of processing and the entirety is eventually reconciled into an aural image - what we think we heard. It is all very fascinating and far from completely understood science. I have been blessed to know some outstanding Otorhinolaryngologists as part of my learning. Audio engineers, even the best, barely scratch the surface.

One circumstance in play is that the temporal domain is not limited to the 20kHz frequency domain limit. Onset transient form and integrity which we can reliably hear, translate to wave-forms in the 200kHz range - that's 10x the frequency domain limit. Such variables are routinely ignored or dismissed by many audio scientists and engineers, in great part because they are inconvenient. The effort and knowledge to design and engineer a product (Thiel speaker) which honors time and phase along with the traditional domains, is orders of magnitude more complex than the generally accepted models would require.
Andy, your closing statement is true. "First order filter . . . does not have phase distortion". Again, we got in trouble over phase distortion earlier. First order is correct on all fronts. All other forms, such as 4th order linear phase, possess forms of phase distortion including pre-ringing and other anomalies. Those distortions can all be managed and valid products are designed with such work-arounds, the ear-brain is a magnificent synthetic filter. It has been said here before: the kinds of care required to produce a speaker which honors phase/time is by necessity a very thoroughly engineered speaker. Many subtle problems which can be ignored in non-coherent speakers become very obvious when phase coherence is introduced, because the auditory mind considers those sounds to be real rather than electronic facsimiles.

Andy, I think the step response may be the most useful tool in the kit. With knowledge, it contains the whole envelope, including frequency response.

Yes, dogs' hearing goes higher. Don't let your dog or cat near your tweeters!

Andy - there's too much to chew on here. But I can comment a little.No I do not think we hear tone above 20kHz. And I know that dogs do, and that Natasha hears bats talk and that fish sense 50kHz signals.
David Blackmer (DBX founder) and others have demonstrated that we can detect the presence or absence of 40kHz tones when riding on audio frequency tones. We also know from auditory research that impulses are processed in the time domain. In other words a crack or snap is perceived directly as a crack or snap with directional and other information that is not tonal. That impulse is further decoded in the brain, to "hear" its component frequencies much like a Fourier Transform,.

I am not claiming that a coherent speaker plays higher tonally than an incoherent speaker, merely that the temporal content is processed and "heard". Some individuals are quite sensitive and others completely insensitive to this temporal / impulse information. My suspicion is that Thiel customers probably fall in the time-sensitive camp more often than normal. 
My upper limit is now 4kHz, dropping at 12dB/ octave. So I'm down more than 24dB at 20K. However, I can hear the artifacts of different digital filters working in the range of 20K and above. My point is that the sonic characteristic of tonality is only one aspect of hearing and does not define the limits of auditory input. In my opinion, which is in good company albeit in the distinct minority.
(A fascinating observation is when playing with the back-firing second speakers a couple weeks ago: I could tell more about the various digital filters when playing the filter changes from the rear-firing speakers than when playing from the front-firing speakers. Also, polarity reverse of the rear-firing speakers did not change my ability to perceive which filter was in use. Go figure!)

Perhaps more to the point in speaker design, we at Thiel systematically discovered the auditory - emotional - holistic importance of accurate phase/time component in the musical signal. In particular, the absence of phase distortion lifts a mental veil which allows the audio brain to see more thoroughly to the essence of the sound. Sound processing is processor (brain) intensive, and removing the big demand of reconstructing time/phase information in a scrambled signal frees the brainpower to perceive other subtleties of the signal (in my considered opinion.) That effect might be called psychoacoustic, but it is nonetheless real given the fact of auditory processing system limitation.

My present work on lifting a veil for the Renaissance revitalizations makes use of this insight. I would not even hear the veil on a higher order system. But I can on this minimum phase system, and I can hear considerable detail and make and test constructive hypothesis, all well below intelligibility on a high order system.

Andy - in re-reading your question I see that your hypothetical speaker spec is entirely in the frequency domain, requiring playing and measuring sine wave tones. But, I am addressing the time domain. Jim specified some of our speakers in mS rise time. I don't have them at my fingertips. But in the lab during CS5 development I saw the rise-time graphs. Doing the math on those slopes results in 200kHz frequency domain equivalents. I'm saying that time and tonality are different animals and for best understanding should not be confused.

Yes - the impulse response contains both time and frequency information which are related in known ways decipherable by Fourier and Hilbert Transforms. But, I am referring to the auditory-brain mechanisms which perceive frequency/tonality differently from impulse/time. This area is much more obscure and unstudied and, I believe, contains they key to understanding why some folks think phase/time coherence is valuable in music reproduction.

I land firmly in that camp - that it matters. But most of the audio engineering community (Toole and others) believe otherwise. My extensive personal experience leads me to value it and therefore try to understand it. I also know how easy it is to demonstrate the false negative premise - to 'prove' anything isn't so.

Over the years there have been many reviews and comments regarding how well details can be heard with Thiel speakers. Recall John Atkinson having to re-master a recording when getting the 2.2 for review, because he could hear edits and punches which had previously gone un-noticed. I recall a commenter stating how 'screwed-up' the Thiel 3.5 was because the orchestral recording sounded like the listener was hanging from the rafters! Guess what? The mics were hanging from the rafters. So, I consider his condemnation as a compliment - the speaker allowed apprehension of spatial presentation masked by even very expensive studio / mastering monitors.

This spatial ability is not related to frequency response. There are many speakers with far flatter frequency response because first order requires very broad range of all overlapping drivers, operating far out of their comfort zones. Thiel went to all that trouble to get flat-enough frequency response because we were and remain convinced of the musical importance of coherence, even if most people don't care and most experts dismiss its validity. That's what specialty companies do, they propose their unique vision. 

JA - the SCD-1 is sick. After a few discs, it would not play, would not open its lid and showed bogus text . . . It is at the shop, needs a new master control board, which Sony does not support. I'm looking for a used board.
But . . . while it played, it was pretty grand, both on CDs and SACDs. Compared to my reference Philips CD-80, which was SotArt in 1985, the SCD-1 was more relaxed and vibrant. I do hope to get it back someday.

JA - I use the CD-80 either in-toto or as a transport to the PSAudio Stellar DAC-PRE. The performance of the two signal paths is similar. The PS affords the ability to select low-pass filter types and remote selection of inputs and volume control. I use multiple signal paths to 4 speakers under test to learn various performance aspects.

Andy - Tonality stays intact far above 20kHz, and plays some role in perception. I have auditioned mics / preamps flat to 50K and 40 and 30 and 20kHz.  I along with most people can hear the difference. Go figure. That fact is not questioned in the recording community.

You brought up limit of eardrum vibration above 20kHz. That is a subtle question about which I know only a little. The eardrum is connected via the ear bones to the cochlea which is a hydraulic-mechanical receptor. The eardrum is an impedance matching device from the low-impedance air to the high-impedance cochlea. The drum (transformer) is locked to its output side (cochlea), which limits its upper frequency response to around 20kHz . . . unless partially decoupled in various ways, but lets call it locked.  

But, that's only part of the story. The cilia - inner hairs in the cochlea which generate the auditory neurons - are embedded in a basilar membrane which changes its own charactristics to bias the cilia for differing functions, which include signal sampling (reading sequenced impulses such as every 100th peak, etc.) Now, the basilar membrane is known to respond to external stimuli including (but not limited to) inputs from the forehead and mastoid process skull bones, the phase relationships of those inputs being important for basillar bias functions. Hmmm.

We are barely scraping the surface here. The point is that the inner functioning of the ear mechanism itself is vastly complex, even before the neuronic energy is sent to the brain for processing. And, by the way, the left ear signal goes to the temporal lobe and on to cerebral processing, whereas the right ear signal goes directly to the auditory cortex to register its primal and emotional content and link to smell, taste, memory and the endocrine system. The multiplexed (left-right) signal begs to be reconciled for complete satisfaction. 

The more I study and make connections, the more I am convinced that everything matters, and that dismissing some aspect is arrogant. Note that the engineering community's dismissal of phase importance is based primarily on ABX testing. Note that such testing may have less to do with the hearing under test than to other brain biases. Note that executive - judgement - choice functions take precedence over more subtle functions. I posit that the test set-up (distinguishing and choosing A or B with consequences to success-failure, professional reputation, etc.) may be usurping the brain-power required for pure auditory absorption of the musical (or just sonic) content. The ABX test is the scientific gold standard, but it is highly suspect to me.

George - by tonality I intend to mean the whole perception of tone, which includes the fundamental and all the overtones. Tonal information, as I understand it, is processed differently than time information.

A very interesting, to me, aspect is the interplay between tone and time. I am presently working on a new termination scheme of the piano string at the bridge. Various schemes deliver various temporal envelopes relative to the frequency (tonal) response of the note.
(all related to the impedance variables at the bridge and the length and tuning of the back-scale between the bridge and the string's final termination.) The fascinating aspect is that the fundamental is only required momentarily, for the brain to "get it" (understand the harmonic structure), rather than having to create a phantom fundamental inferred from the upper harmonics (which takes lots of work.) Anyhow, once the real fundamental is there for a instant, the upper harmonics make sense, and then the phantom can drop out and the upper harmonic structure is more intelligible on its own. This harmonic development / sonic motion is related to the phase interactions of the string and bridge, which can be manipulated. Imagine that.

Hi Andy,I believe the ear drum maxes out at 20kHz.#1: the cochlear envelope gets inputs in addition to the ear drum.They mostly modify the conversion from sense (electromagnetic energy) to neuron output, but also direct cochlear vibration produces modification. Also, there are other types of auditory input in addition to vibration. Think time-impulse, not tonal-frequency.

#2: False assumption. Brain gets inputs from cochlear cilia (hairs) which can be stimulated various ways. Plus additional inputs (beyond cochlear cilia). It is known that video input affects the ear (dizziness from spinning alters sound perception) and bright lights (strobes affect hearing), and so on. The brain is a parallel processor.
#3: Probably mostly true, but the ear-drum-stirrup system obeys the mass-stiffness-damping physical laws and therefore falls off rapidly above its upper resonance. And I don't know how much importance to assign to the residuals. Psychological damage can be inflicted via super-sonic sound that is not knowingly heard. On the other hand, there are thresholds below which we don't knowingly hear, and there are masks where we become unaware of sound beyond some marker, such as a resonance frequency or FR hump. More questions than answers. 

#4 ( A lot of people). That's a good example. Sound below about 20Hz is sensed via the solar plexus (chest-diaphragm) as well as mastoid process (skull behind ears) and forehead. The head bones directly modify the cochlear response, but the solar plexus couples directly with the right-brain auditory cortex, with speculation about other skin-body involvement.
Historical note: The Germans developed a sub-sonic technology in the 3 to 5 Hz range to play before Hitler took stage. People puked, fainted and became agitated. As he took stage, they stopped the signal for a state of comparative euphoria. These low frequency tones can be lethal, infra-sonic but definitely directly related. Horses can "hear" a train more than 5 miles down the track. They sense that 4Hz wave through their hooves. I mention these things as examples among many to illustrate that hearing is complex beyond 20Hz to 20kHz eardrum vibration.

Thosb - Wow, what a ride! The topic of amps driving Thiels is, of course, of great interest and concern to me. Jim did his thing for his reasons, and I disagreed (about impedance mostly), but he was the designer-engineer. The interacting variables are very real. My hope was that by developing our own in-house driver manufacturing we could circumvent some of the hard problems of magnetic gap electrodynamics, etc. that limited the overall system design. Thiel drivers did indeed become quite radical. But to my dismay, the system impedances fell rather than rose, which disappoints me as I re-assess these designs.

I wish that Thiel speakers presented a minimum 4 ohm load! That didn't happen. The nearly magic work-around that a poster mentioned on that thread, is to add a second input for a separate amp for the 3 bass drivers. Most of the problem evaporates, but cost is incurred for 2 more amps.

I find it interesting that in all that discussion and examples, that Benchmark AHB-2 didn't surface. My question about it on this thread also got no response. Is it invisible or somehow inappropriate? Absolute Sound rated it Class A. I find it exceptionally clean, uncolored, versatile and affordable. Am I missing something?

I bought a pair of AHB-2s about a year ago and am thrilled. I specifically want to hear bridged vs stereo and how this amp stacks up against my well-known Classe DR9s (also a pair). They are remarkably similar and grain-free. The Adcom GFA555mkII exhibits the kind of problems that plague Thiel users. The 3 amps provide a good window into what might be going on.

BTW: John Siau (AHB designer) told me the following, based on my speaker schematics and his load analysis:CS7.2 Stereo or mono (bridged)CS5: Stereo onlyCS3.7: Stereo onlyCS3.6: Stereo onlyCS2.4: Stereo onlyCS2.2: Stereo or mono

Believing him, I have nevertheless tried both modes on the 2.2 and 3.6. The 2.2 does fine either way (Its impedance is higher and more benign.) The 3.6 sounds a little sweeter on stereo. When bridged and pushed hard the amp clips with very effective momentary protection. Amidst the thunder the only evidence for me was seeing the red lights flicker. This amp is Class H power feeding a class A output. Very unusual distortion profile. Essentially clean until it's not, which shuts down instantly.

Twoleftears: that single vs dual input scheme is high on my list, but I haven't implemented it yet. I'm wired for vertical bi-wire/bi-amps.

Thosb - the broad brush paints a picture that the select few amps (which you guys end up with) seem to handle the difficult loads, mitigate "the harshness" or otherwise perform well without softening or sweetening the signal. Jim's view was that these are "good amps" which should be used with "good speakers". He tested amps and knew the designers and indeed many of the used our speakers for their design loads.

What I hear from the Adcom is somewhat bland / lifeless, grainy and dry. Not bad. Pretty good compared to many, but fairly vanilla compared with better.

Regarding dual inputs: I'll recap. We identified dual inputs as a good solution and used it in the CS3. Problems occurred when people used radically different cables for bass and treble and/or bi-amped with differing amps, including unmatched gain. These hassles were unacceptable to Jim, who put tons of energy into matching to within a fractional dB across the spectrum. Kathy polled dealers who thought at our price points life would be much simpler with single inputs. End of that story.
But the back story doesn't change. Since the current draw makes many amps misbehave, even if marginally, separating the bass loads from upper loads cleans things up enormously. There is a perceived problem by some that jumpers degrade the sound if you choose to single-input. I don't hear it when using Cardas high purity copper jumper plates, which are affordable and allow the user to substitute with jumper wires if desired. I like vertical bi-amping where one channel drives the woofer and the other channel drives the mid-tweeter. I don't have a good sample, since my amps are pretty good and I only have 1 Adcom stereo. (The second one arrived DOA and I opted for a refund unstead of repair.)
I suggest adding the second pair of posts when modding the XO. Beetle may chime in - he looked in to that with his 2.4 upgrade.

Prof - the most modern Thiel I have in the HRGarage is the 1.6, which predates your 2.7s by a decade. And I don't hear any of those harsh attributes in it either. There was steady progress made through the years. But the early products could and would often sing sweetly. The positive reviewer experience rarely gives any mention to the complaints some observers proclaim. I'm developing some working models, but still there's a lotta mystery.

George - C'mon, please say more.Thosb - You're welcome. These questions fascinate me this time around.

George - I've never actually heard electrostatic phones. I use Beyerdynamic 770s live and Sennheiser 800S in the studio-lab. I chose them for high quality neutrality and because many top-notch recording and mastering engineers use them.

Of interest is that the handling of stereo signal is different for in-room stereo and in-can binaural playback. Great recordings play well in both environments, but many ordinary recordings do not. It would be fascinating to learn whether that qualifier makes for good playback on Thiel / Vandy speakers. A recording that plays well on both stereo and cans must have its phase-time information intact and refrain from 3-D tricks of the trade. I bet those "proper" recordings would sound right on phase coherent speakers. Anybody know anything about this topic? I'm just surmising.

Tom

George - I auditioned the HD600s and the 800s. The 800-S is a big step up due to controlling a resonance at about 8K and the angled circular transducer. As I mentioned, my decision was for alignment with the recording community, not doubting that your electrostatics might sound better. BTW, I see the Audeze cans making serious inroads into high end recording.

Looking for CS1.5s. I've spent a good part of the past year building a lab with measurement equipment, various playback chains, a hot-rod garage of models and accumulating knowledge and ideas. Many pieces of the puzzle are in place, and I have decided to take on the CS1.5 as my first project. It is highly rated, well loved, simple two way, good parts availability, and old enough to need assistance. I'll learn a lot from them to apply to more complex models. 2.2 and 3.6 are next in line.

But I don't have any CS1.5s, nor does Rob. So, please know that I am looking for a pair or two as workhorses, in any condition, with or without good drivers.  Thanks for any help you can give.

Pardon me, I mis-typed. The 2.2 and 3.5 will follow the 1.5. Lots of work is being done on the 2.2 which can be applied to the 3.5 which seems to have a strong following, especially in its sealed bass. I'm looking for a pair of 3.5s as well as 1.5s.
Tom

Beetle - thanks for the leads.
JA - I'm working on real quantities in the field. Thiel didn't compete well at its lower end. Dealers I knew thought those products made no market sense - they were too radically different from their price peers. In addition to quantities I'm looking into the 1.7 XO. A product announcement by Steve DeFuria (first sales manager of New Thiel, and old friend of mine) says they're 4th order Butterworth, and the Frequency Response Curve shows a 7.5dB fall from 100 to 20K Hz, a somewhat exaggerated Harmon Curve. I can't find reviews on the CS1.7 that show a bank of measurements. 

Prof - The 2.7 is on my long list. I am gaining experience by taking on older designs with more room for improvement and more urgent end of capacitor life issues. I am learning a lot as I go that will all apply to more recent models such as the 2.7, which I consider at the pinnacle with the 3.7 of Jim's art. I hope to form some sort of organization to implement the design modifications I am creating. But for now, the 2.7 seems stable and respectable as it is.

Prof - my present work on these products strongly suggests that "neutrality vs musicality" is not necessarily a dichotomy. The assumption that we must sacrifice Articulation / Neutrality / Resolution in order to get "Musicality" is not necessarily so.

And Unsound's slippery slope is certainly slippery, but perhaps doesn't slope the way we thought.

The work I am doing seems to increase A/N/R and increase Musicality by removing some sources of propagation aberration which have plagued Thiel speakers in varying degrees over the decades. Trials in progress.

The 1.6 was introduced in 2002 and sold approximately 3000 pair in its 10 year run, about the same as the CS1.5 from 1993 to 2002. All 1.6 cabinets, drivers, final assembly and testing was done in Lexington.  My #1611-12 pair have Lex crossovers with Axon caps on printed circuit boards. "Late-date"CS1.6s (probably after Jim's death in 2009)  had crossovers from FST.
I have done considerable investigation with the 1.6. I find it to be quite strong in all respects. My upgrade work has centered on physical elements with electronics review to come later. I am quieting the baffle for surprising increases in delecacy, harmonic detail and spatiality (as also is shown even more-so in the 2.2).I credit this forum for inspiring this exploration -specifically the questions about the Vandersteen baffle-less approach and the comments about being "harsh, aggressive, shouty". In reconstructing the product time-line, I realized that I had effectively dropped out of design evaluation by the time of mid 90s 3.6 finalization; and I would have been the person to explore non-electronic causes of subtle distortions. So, I'm playing catch-up 25 years later. And the results are enlightening on many levels of product performance and life's deeper questions.

The CS1.7 is a different story. Its development was finalized by New Thiel via Mark Mason, formerly of PSB. Shortly after the sale, Steve DeFuria was hired as national sales manager and he contacted me to arrange a consultancy for product/ philosophical/ historical backgrounding for the new owners. The new owners were not interested in the "old perspective" and I was not invited until a couple of executive generations later when I judged all had been lost.  The 1.7 was a focus of contention for Steve. The new CEO wanted to call it "Coherent Source", a moniker they had bought. Steve judged that it could not honestly be called such due to its 4th order crossovers and resulting phase distortion. I have read conflicting reports re its slopes, so I don't know where that argument landed.

The 1.7 had an upgraded tweeter and a woofer with a star diaphragm. It got some good reviews, but did not get formal reviews from Stereophile or Absolute Sound. I'm guessing it sold very poorly in the confusions of leadership transition.

Batmanfan - I was long gone at 3.7 time, so I can only give you a sketch. Rob says nothing had changed since my days. The tonal balance and hard-core engineering was done in the chamber, which was semi-anechoic with previously delineated dimensions, but roughly 20' high x 30' wide x 40' long with the tweeter at 10' above the ground. Outdoor measurements and ground-plane measurements all went in the mix for tonal balance.

Listening was done in our built-to-purpose room at 14' high x 22' wide x 34' long (more or less from memory). Big room with furniture, plants and some wall panels. Big enough to support and report on what the product was doing. Smaller rooms, especially approaching cubical and/or with half or double dimensions are more problematic. There are various ratios known to work better than others.
A room that sounds good is good. And women tend to feel it wen it's right. Good luck.

George - Nice system, nice room, and good solution.

Unsound - I am being excruciatingly careful to avoid editorializing the sound. We called what many brands do "euphonic engineering" - to knowingly alter the sound-field for desired illusions.
A look behind the curtain: I used my modified CS1.6s as sound reinforcement for a live acoustic concert last night in our 12,000 cubic foot Village Arts Center. As usual during sound check, I compare the unamplified house sound to that in the headphones (Beyer770Pro), to that through the speakers. The naturalness was comment and question-worthy from the musicians, two attendees and the house manager. To date there are no changes to drivers or electronics or cabinet walls. The baffle surfaces have been modified for a qualitative improvement which genuinely pleases and encourages me. 

Andy - No 2.7 and 2.4 are not the same woofers.
Longer historic perspective answer:A new model from Thiel included new drivers, either specifically developed for the new model or trickled down from a more expensive recent product. Ex. the CS1.6 woofer was borrowed from the in-house developed CS7.2 mid-woofer. A newly named generation had new drivers.
The 2.7 woofer may use the same cone as the 2.4 (I don't know). But the 2.7 woofer was developed in conjunction with Warkwyn-Canada, along with the crossover. That development consumed tremendous costs, proving that outside engineering could not be afforded for Thiel to keep breaking new ground. In Jim's time I believe the 2.7 coax would have been a new driver based on the 3.7 concept. In fact, he spoke of developing such a 7.3 coax. A smaller diameter mid-plate would allow a higher crossover and perhaps a smaller tweeter to higher resonsnce-free extension. That hypothetical driver, along with a star cone, would then be trickled down into the model 2 - and called the 2.5, the next generation of the model 2.

The 2.7 is certainly an accomplishment, and a tribute to Home-Team- Thiel's dedication to creating a legacy worthy of Jim's 3.7 work. But it is less of a product than Jim would have engineered, given the time.