Thiel Owners

Unsound - what do you consider the low impedance limit of the AHB-2?

YYZsantabarbara - here are some thoughts about Thiel product versions - upgrades follow this general pattern. A product is introduced with components, especially drivers, being prototypes and early small production runs. Within the first year it becomes obvious through 100% production final testing that some tweaking would better center the speakers (made of real, settled production parts) within their window of acceptability. This first revision is generally not announced, since no real circuitry or specifications are changed - merely subtle improvement of more speakers. At some later time, after ongoing feedback from dealers, reviewers, users, staff listening and Jim’s own scrutiny, a second revision is made which is often more significant and serves to upgrade the perceived shortcomings of the product. Sometimes this second revision carries a price increase. In other words the cost / performance plateau is adjusted toward optimum. In some cases the upgrade is significant such as the CS5i (improved); in some cases it is more subtle, but always more optimum, what the product wanted to be when it grew up - the mature iteration of the design.

In the case of the 3.7, here is what I found. In January 2007 the CS3.7 was introduced (original version - I have no layout or schematic.) On Jan 12, 2008 revision 1 was introduced at approximate serial number #517,18. On October 4, 2008, revision 2 was initiated at approximate serial number #881,82. Revision 2 is the current, mature layout.
The changes in revision 2 over revision 1 are significant: 3 changes, all in the tweeter feed section - addition of a bypass resistor, and changes in coil and capacitor values. These changes affect the shape of the roll-in of the lower tweeter to optimize the blend with the midrange roll out, cleaning up frequency and time-domain coarseness in the upper midrange. Note that the 3.7 UMR got some criticism and someone offers an after-market kit to address it (I’m not recommending that kit.)

All in, I would suggest you consider the upgrade if your speakers are under #880 and upper midrange "rightness" is a concern. Note that many rooms with hard surfaces or dimensional problems exacerbate upper midrange glare and ringing. A problem in a ’bright’ room can go away in a ’sweet’ room. Note also that if you're in there making changes: the added 20 ohm tweeter feed resistor and the existing 12 ohm should become Mills MRA-12s, and the feed cap and its bypass should be upgraded to a ClarityCap CSA 16uF at as high a voltage as you can fit and afford ($25-$35 / each). Just my opinion from my hot-rodding experience.

Have fun.

Thieliste - Rob Gillum at Coherent Source Service would know. The third New Thiel CEO told me "less than a couple thousand"; but then he was defending the decision to abandon Jim's designs. My impression is that marketing was in disarray after Jim's death in 2009. After taking on Crutchfield, the US dealer base evaporated and so forth. If anyone finds out, I'd like to know.

Wow guys - I take a break and you all go at it! Unsound alludes to a "problem" in such a long, detailed thread as this one. Lots of information would be redundant for regulars, but helpful to new participants. I appreciate it when someone directs others to where they might access the discussion.

Regarding concrete repair - look for expansive grout at Lowes, etc.

Paradisecom - congratulations on your CS2s. In many ways that is the seminal Thiel design; it took the concepts generated in the model 3 and refined them for a smaller space and source material at a lower price. The CS2 sold more units than any other Thiel product ever - over 11,000 units. All the Renaissance work I am doing on the CS2.2 will be retrofittable to the CS2. Regarding black laminate - what a trip. I wanted to bring a polished lacquer piano black finish into an affordable form. It became sadly clear that was impossible. Material flaws, along with susceptibility to damage in production and/or shipping and use led to price increases and unhappy customers. It remained in the stable at an upcharge, but we never promoted it due to its difficulties.

Thoft - you have a problem. My 3.5s measure 4.8 ohms DC resistance which seems right for their performance impedance curve. Rob Gillum can help you troubleshoot. If it comes to replacing parts, consider the upgrades we’ve been talking about here.

Scubabird - Rob’s answer #3 invalidates part of my previous response about Thiel revisions. Sounds like 3.7 revision 2 was to recalibrate the changes made by migrating to PC boards. BTW: I agree with Rob on liking P to P on Masonite better than PC boards. Go to Rob for any problem - he has made and repaired every aspect of every Thiel product since 1988.

Regarding the Benchmark AHB2 amps. I would appreciate public discussion here driving Thiels. They are in my stable and your collective opinion would help me calibrate their performance compared with other high-performance amps, which I don’t have access to.

Papasmove - good score on Jim’s Krell FPB-600. I was your auction under-bidder - dropped out because I have no business owning that. FWIW, that amp was routinely upgraded. Dan D would send Jim the latest tweaks for his feedback. Rob G was prepared to spend up to $10K for it, but deferred to me who dropped out. Good score.

Back to the lab. I’m getting close to tri-amping, bi-amping, single amping comparison on the 2.2s.

Regarding the cracked concrete baffle. The chicken's way out (easy and little danger) is to smear concrete caulk on the inside to stop the airflow. Then dribble thin epoxy or cyanoacrylate into the crack from the front and either finish the show face or not to cosmetic taste.

Like ultra-low impedance, I judge the concrete baffle to be an inadequate solution. It was changed to a stone x polyester substitute, which required considerable ventilation of fumes - the joys of manufacturing. I've mentioned my preference for the Hydrostone solution that ended up in Hales counterparts. 

YYZ - what a system! Thanks for chiming in. I landed on Benchmark for my use and love it. thielrules is correct that low impedance loads are harder to drive when bridged. John Siau, the designer. evaluated all Thiel performance curves and chose only the early models plus the 7.2 as suitable for mono. But so much depends on particulars. My (odd) room is effectively fairly large; I listen in the 85dB range max (except for short bursts of stress testing.) The AHB-2 has excellent protection and excellent LED monitoring. I overdrive far more in stereo mode than mono on the PowerPoint, SCS4, CS2.2, 3.5 and 3.6 (all I have.) Additionally, the internal protection is so good and so fast that there is little if any danger of a distorted signal passing through. They are a different type of amp entirely. I land on bridged mono to stay out of clipping almost entirely.

Awhile back some of us on this forum (perhaps behind the curtain, I don't remember) compared AHB-2s in mono vs stereo and agreed that stereo sounds somehow purer/more delicate - subtle difference. John Siau is convinced that we are hearing the halving of damping factor in mono and that halving the cable length would make them 'sonically identical'. I'm skeptical of identical, but he has a valid point.

Today's tri-amping experiment hasn't lifted off, but I hope to be ready for Natasha's visit tomorrow afternoon. We'll be comparing different amp setups through the outboard crossover. I'll report after I've gathered some experience.

thieliste - what's the price tag?Anybody tried the new PS Audio 1200 watt monos? They state 2ohms as suitable for musical transients, so I donno.

Unsound - I agree that the proper rating for the 3.7 would be 2.5 ohms. Nominal impedance is by convention stated at or near the minimus after the bass anomalies. If that trough is deep and steep the rating can be upped a little, but the 3.7 does not bounce back and indeed stays below 3 ohms to 500 herz, where lots of power is required for mid-bass output.
I find Jim's adherence to low impedances misguided and limiting. Not many amps perform well into such a low impedance.

JAFant - thanks for the cable tips. Too many variables, too little time.I have direct experience with Mogami from the pro world. It's considered by many pros as best of form for mic, interconnect and speaker cable. Their best is quite good, but direct comparison to Swiss Vovox mic, or Morrow interconnects leaves Mogami sounding pleasantly veiled to my ear. I would gladly adopt some Acoustic Zen or Synergistic Research into my rotation if they come my way.

I really appreciate amps with clipping indicators, since there are so many variables of room, level and loudness preference - it's hard to predict amplifier power need; except that more is better, but usually at the cost of sonic finesse.

Rules - to your question of other benefits the answer is YES. I am working with older models of moderate (88dB/2.83volts range) with somewhat higher impedances (6ohm nominal). Let's say my amps are beefy enough to hear no clipping and to see little if any clip LEDs.

When using an amp for each driver, there is an unmistakable sense of ease and transparacy. Returning to the stock speaker with 1 amp imparts a hard edge, especially with loud, complex material. I love the tri-amp configuration, but that multiplies the cost of amplification.

A feasible solution would be to use amps available on the used market. A primary problem is gain-matching the amps. I am running the mids and tweeters in vertical bi-amp mode where each driver is driven by a channel of a stereo amp. Assume a matching amp for the other channel and there are no problems (after you get a splitter to send your preamp line out to both amp channels.) Now, the beefier woofer amp must be gain-matched to the smaller stereo amp. I am sending my source signal to two parallel chains, each having a preamp with volume control for manual level matching. But that's not a real world solution.
I am consulting John Siau regarding gain matching of the AHB-2 in stereo and mono. I am not certain that the levels are matched between stereo and mono. I'll report when I learn more next week. In my dreams I imagine 4 AHB-2s with each channel having a stereo amp for the mid and tweeter and a bridged mono amp for the woofer, which also controls the subwoofer.

I want to modify yesterday's statement about the deep bass performance of the AHB-2. The more I listen the more I like it, and my in-room sound pressure measurements suggest that the bass amp is weaker. Therefore my call to Benchmark regarding gain; and here's hoping they can be matched. Then, of course, funds would have to be found.

As a point of Thiel history, Jim used very good amps to design the speakers. His attitude was that making a good amp was the ampmakers’ business, and making a good speaker was his business. We generally had on hand the best from Levinson, Krell, Audio Research and others for comparison. His workhorse for the 3.7 development was the Krell FPB-600.

But at shows, Thiel usually exhibited with amps priced commensurate with its products. No $30K amp for a $10K speaker. Bryston was often used. I found the Bryston amps rather coarse compared to the better stuff at the factory. Many reports said that all changed with Bryston’s ’cubed’ series - which are more refined. Thiel used the a cubed series amp (perhaps 4B3?) to introduce and show the 3.7. That was the combination that George Cardas dubbed the best sound he had ever heard at a show. Bryston offers trade in and upgrade packages. I suggest that the ’cubed’ Brystons come very close to supporting Jim’s design intent for the 3.7, even though it doesn't meet the double-down standards for full current delivery into low impedance loads.

Unsound  & yyz- thanks for the catch. Seems I am confusing my stories. The 'cubed' feedback stands as exceedingly complimentary; but I don't remember from what source. 

Keep the time domain in mind, especially for phase coherent speakers. On and off axis radiation patterns are different as the frequency rises. The speaker is balanced into an "average" environment with assumptions made as to where the front and side walls "might likely" be. Those assumptions never include placement near a wall. Perhaps you can unscramble the changes with DSP, but the differences with placement will be significant.

Yyz - the definitive test is to make a momentary connection from a 6 volt lantern battery (or other 6 volt DC source) to the XO inputs. All drivers should move forward. You can readily see the woofer and midrange move, but may have to feel the tweeter. And Thiel uses silver solder which has a higher melt temp than utility solder. A 140 watt gun is just right.

Yes, the side and front wall reflections are quite important. Your room is quite narrow, since the polar pattern of the CS3.7 is quite omnidirectional. Can you try putting them on the long wall?

unsound & thielrules - about individual amps. I’ve been comparing configurations these past few days and conclude that it’s very murky water. I have matched pairs of Adcom GFA-555 mkII, Classe DR9 and Benchmark AFB-2s. The power is similar, but the clipping characteristics are different. Even with using same source, preamp, cables and speakers, the amps’ characters change when stereo or bridged and how hard they are pushed. All things considered, it would be hard to make any ’best recommendation’. I agree with unsound’s thought about ’same amp’ for bass and treble. Gain matching is very important as well as overload characteristics.

At this point what I can say for sure is that among my amp stable, the AHB-2 is the cleanest, clearest, most harmonically convincing. To my previous comment about its possible bass ’deficiency’: I suspect it is outputting most accurately, even though other amps might be more appealing. After speaking with John Siau of Benchmark and poring over test results of all the amps, I’m convinced that the AHB-2 stays extremely clean (until it clips), whereas other amps delay bass frequencies which is experienced as hanging longer in time, and produce harmonic (distortion) addenda which is experienced as more amplitude. Combining time delay and more harmonics produce bigger bass. But, the AHB-2 bass is so clean and articulate with considerably more inner harmonic detail. The problem still remains that it admittedly produces "less" apparent bass than other amps, so the producers’ intent may have more bass than the listeners’ experience with the AHB-2.

My preferred setup is running a pair of AHB-2s in bridged mono, each driving a full-range speaker with 3 separate, identical cable runs (or two runs that combine midrange and tweeter feeds. I rigged some 6’ and 12’ runs and cutting the runs to half length increases damping factor by 2 and tightens up the bass that was loosened by bridging. If I could afford to splurge, I would use 4 AHB-2s, all bridged. One for each channel’s woofer and the other for the mid-tweeter. But, I don’t feel the need, a bridged pair doesn’t clip in my situation, and unlike normal amps, the AHB-2 distortion stays near zero into any drivable impedance until it clips. JS says that impedance limit is around 2 ohms, so some Thiel models are in jeopardy. But I haven’t experienced it with my 2.2 and 3.5 testing. I wish Jim had kept his loads above 4 ohms nominal, 3 ohms minimum to stay out of trouble.

Unsound - I agree to wanting 4 ohms minimum which would roughly double the impedance of many Thiel models, making them far easier loads to drive with lower amplifier distortion and fewer cable interactions. Jim committed to underhung voicecoils as a way to reduce motor distortion by an order of magnitude. Walter Kling developed the methods and machines to make those drivers. He shared that industry driver manufacturers considered them nearly impossible to make and therefore expensive and ill-advised. Jim and Walter took that as a challenge and took it on and never looked back. One of the downsides includes the coils being only a few winds long (short?) x 4 layers thick, which is precarious geometry indeed. More turns would raise impedance, but also add mass and mechanical reactance in a system short on gap flux due to the thick coil. The feasible balance point seems to have been where he landed. He wasn't really out to make our lives difficult driving them, it just worked out that way.

Thielrules - it all depends. A very big deal is running out of power. The Adcom and Benchmark have overload LEDs. Listening at 95dB peaks at listening position, the Benchmark overloads consistently in stereo with one amp channel driving the woofer and the other the mid-tweeter. The bass amp can be bridged and its input sensitivity reduced to match the stereo upper amp. The upper stereo amp then becomes the overload limit, so it also must be used in bridged mono. Clipping is unacceptable. The Adcom at twice the power is better, but marginal on the mid-tweeter. It has no input sensitivity selector and therefore in stereo it cannot be easily gain-matched to the bridged woofer. So no go for tri-amping. Classe DR9 has similar power to AHB, so I assume it clips even though it doesn’t give LED proof. If you had 4 amps and could dedicate one to each woofer and one each to the two mid-tweeters, that is theoretically better than a single bridged amp to all three drivers, at twice the amp/cable expense. I am personally at peace with a Bridged Benchmark driving each channel with 3 separate cable runs or two runs: one to the woofer and another to the mid-tweeter.

To your question of best configuration - Because low impedance loads cause higher distortion in normal (non AHB) class A/B amps, I would prefer a stereo amp with one channel for the woofer and the other for the mid-tweeter. Those amps would need to be a few hundred watts minimum per channel into 4 ohms in order to stay clean. My amps in my space don’t deliver the goods satisfactorily in stereo mode.

Let’s do some history. As you know, the CS3 was set-up for bi-amping / bi-wiring. It separated the tweeter from the rest of the signal because the equalizer boosted the bass which included contribution from both the midrange and woofer, so they couldn’t be segregated to different amps. Audible improvement was gained by separating the tweeter. But the preponderance of users chose small SET or tube amps for the tweeter with no consistent way to gain-match the low frequency amp. Solving those variables would have required a different kind of dealer. Jim assessed that we didn’t have that expertise in the field to his satisfaction and removed the bi-amp /bi-wire option.

The scene is different today in that remaining Thiel users are likely to commit to getting it right or staying on the sidelines. It is tricky business, especially in the absence of clipping lights and with uncompressed and/or otherwise very dynamic music. Underpowering makes distortion and distortion fries drivers. Be careful.

JA - what a trip indeed. Circumstances have prevented progress in ways that many here assumed or wished for. I’m not yet discouraged; and I’m stirring the pot every day. My personal interest drives me to decipher some of the mysteries of Thiel and the idiosyncracies of its product performance. As you know, I have speculated that phase coherence allows the audio-brain to scrutinize sound differently than non phase coherent sound - as I formerly have written here. I beleve that, but many elements don’t neatly fit into that narrative, including the opinions of knowledgeable practitioners to the contrary. My search and questoning have taken unexpected turns.
An early assumption of low-hanging fruit was crossover component upgrade. Indeed good results were gotten there; similarly hookup wire and softening the wave launch surfaces on the baffle. But a derail occurred serendipitiously on a flight of fancy when I fantasized with an audio friend about some aha moments during early product development experiences in the 1970s. We identified the let-down when the ’hanging sculpture’ of the free-air crossover-in-development was nailed down and put in the cabinet. Magic went missing. Long story shortened, we re-created a bird’s nest crossover hanging in space. And, guess what - magic.

I have developed and tested some hypotheses and solutions and identified some obscure aspects of performance that migrate the musical experience from somewhat canned to substantially transparent. A relevant result is how ancillary equipment interacts with my speakers under test. Thiel fans have spent enormous time, effort and funds finding source equipment that works. And when it works, it works well. Shortened story: the outboard crossover has opened doors not only to better music, but to finding solutions to some pretty subtle problems, including broadening the range of acceptable drive components while increasing the level of detail, transparency and 'rightness'.

Anyhow, in moments of nostalgia for a company history that never was, I wonder about what we might have built if we had asked these questions and found these solutions in parallel with Jim’s relentless progress in the areas of his interest and expertise - where his innate comprehension of physics met his unique engineering ability to convert his best ideas into uniquely satisfying products. But, there is always more potential, isn’t there. What a trip finding some buried gems hiding in plain view within the platform he created.

Unsound -
As you say, sufficient power is an absolute requirement. I may be naive, but I'm thinking that with good used equipment available at bargain prices, education would be fruitful because many folks could actually afford good to great solutions.
In addition to EMI and RFI from the interactions between the crossovers and the drivers, there is the proximity to metal driver frames and pressure fluxuations. A big deal is that cabinet vibrations necessitate every component being glued down to avoid microphonic and fatigue vibration. Plus the cabinet is a closed cavity, so heat generated by the crossover losses as well as the driver motors, wh heats up everything, changing the component values and circuit functions. It's not subtle. By outboarding I can dump crossover heat at the crossover and driver heat via heat sinks and thermal malpractice and compression are greatly reduced. each component can be mounted for maximum cooling.

The baffle stuff is quite intriguing - newly developed plate resonators to quiet and organize the launch waves. Coupling of driver motion to proper air waves is less than trivial as well is the chaos of early diffraction. Thiel paid lots of attention to that, but more attention is fruitful.

Here's an aside. I can play a woofer in a cabinet adjacent to its mate with the mid-tweeter. Same feed signal. Taking the woofer-induced vibrations out of the (upper) cabinet cleans up the high end considerably. Imagine that. I thought the CS2.2 cabinet was quite quiet, and it is by comparative standards. But better is better. I can remove the cabinet top and bottom to doctor the cabinet walls, newly accessible from taking the crossover outboard. Two versions under development. Underslung Crossover places the 3D network in a vibration-insulated and ventilated chamber under the cabinet while the Outboard Crossover version puts it in a free-standing enclosure about 3' behind and connected by an umbilical to the drivers.

To your point about the flat coaxes. Jim wanted coaxes from the very beginning for their solutions to placement and lobing problems. It took till the SCS in the late 80s to execute the coax and gradually get the outer cone more and more shallow to minimize the squak-effect. The flat-wave solves so many issues.

ampers - I’ll chime in here. The Benchmark AHB-2 has been my go-to amp for about 2 years now. It is unique in my experience for simple authenticity. Regarding their feed-forward, John Siau has written a white paper available on the BM website. In practice, the correction mechanisms are nearly invisible and inaudible. Under overload / clipping conditions (evidenced by the indicator lights), I can hear no artifacts of any kind. The error-correction compares the input signal with the projected output signal and introduces correction before the final power stage. When pushed ’too hard’ the output interrupts momentarily as though the offending peaks are erased, but with no audible distortion, mute indicators light up momentarily - and the music continues. I have purposely pushed the bridged amp into sub 2 ohm loads (two paralleled CS2.2s.) The over-current lights flicker on peaks and eventually the amp shuts down via overheating. No damage, no audible distortion, just safety shut-down waiting for manual restart in a few minutes.

Don’t try this at home. But my experience is that the AHB-2 is bulletproof for itself and its driven load.

In my large room, I run out of power in stereo mode and therefore use 1 bridged amp on each channel. Unlike class AB amps, the bridged distortion graphs match the stereo graphs. But output impedance is double (damping factor is half). Half-length cables makes up for much of the difference.

Considering the relative bargain price of the AHB-2, my dream configuration (seconded by John Siau) is 4 bridged AHB-2s -each channel getting a bridged amp for the woofer and another bridged amp for the combined midrange - tweeter. Power requirement is about equal, since the headroom required for clean midrange peaks about equals the current draw of the bass.

Yyz - yes. 3' cables are optimum if your configuration permits it.

George - I agree that all amps we know, either class A or AB, act worse in many ways when bridged. I recommend you investigate this particular amp, which does indeed act as you say, but its anomalous behavior is limited to its stability into low impedences, BUT if it does become unstable, it tells you via indicators, and protects itself. I had dismissed it for myself before I looked closer and now have used it for a couple of years. Check it out.

Rory at Benchmark says that many customers have requested such an AHB-3. I tried my hand at it. John is adamant that the AHB-2 has enough power. Engineers can be that way.

We wouldn’t be talking about this here if Thiel speakers had 4 ohm minimum impedances.

To clarify for those recently joining the discussion, my observations are based on an unusual room that is effectively large since the listening room has semi-porous walls within a 12Kcubic’ space, in a 30Kcubic’ building without many partitions. I also have modified the speakers for 3 separate inputs rather than a single pair. I listen at approx 90dB peaks.

Under those conditions the pair of bridged AHB-2s never clip.
I had hoped for a configuration with a bridged AHB-2 driving a woofer and another one (adjusted for matching gain) used in stereo mode with one channel driving the midrange and the other the tweeter. Alas, the upper amp clipped regularly in my conditions. But, in less demanding conditions that setup works quite well.

dspr - Rob at Coherent Source Service could check your serial numbers for whether yours were upgraded to the "i" status. The difference was upgraded woofers and possibly an XO tweak to compensate.

For the room bit, I recommend moving them away from the side walls and back wall as far as practical. Just for input, try 5' behind and 3-4' to the sides.

Rules - that's listening position. Peak capture might register 100dB, unless I'm driving hard to cause distress on purpose.

My listening is almost entirely for data-gathering. My chair is on wheels and my spl meter is velcroed to my thigh. 2' square carpet tiles tell me where I am and where the speakers are. Listening distance is generally 10' to 12' out (10' was design distance.) I find more value in terms of speaker distances from walls, rather than between them. Thiel polar pattern is optimized away from boundaries, and many problems result from early reflections. In a 15' wide space, I would rather have 6' between speakers with 4.5' to side walls, than to have 8' between and only 3.5 aside.

lloyd - I'll chime in. I don't know the HMS cables. I do know the StraightWire Octave II (now III) which I can recommend. I can speak generally to the subject, having taken a very deep dive over the past couple of years.

I suggest avoiding any cable with out-of-the-ordinary technologies, unless proven to work both with your amp and speakers. I would put Goertz Alpha in that camp. As ribbon conductors they may react erratically with some amps. But Jim used them including for the 3.7 development and he also used Bryston over the long haul - so they are a good bet. 

My personal experience is to recommend avoiding any cable using non-insulated stranded construction. Every example of this common technique imparts a wooly haze to the sound. On the flip side, any configuration with coated strands has a high likelihood of goodness. Such cables tend toward expensive. I love Morrow which uses individually insulated conductors, cotton dielectrics, and bonded twisted pairs - all technologies the float to the top of my list.

Now, some exceptions. StraightWire does not individually insulate, rather, they compress the conductor bundle bringing the multiple conductors into close contact along their whole length.  Kimber has a multi-gauge conductor strategy which does not individually insulate, but packs them tightly and technically which seems to remove that stranded wire wooly haze. And then there's braid as in Kimber's Black Pearl and Iconoclast's speaker cable (generation 2 is better). The braids use bonded pairs and 'good sounding' insulation materials. 

Wire is reactive and variable based on materials and geometry. I suggest paying less attention to the purity of the metal and more to the insulator / dielectric. I like organics best - cotton, jute, etc. Hydrocarbons are suspect to me, even as shrink tubing or exterior jacketing. Teflon (and its family) are clean and clear, especially when un-pigmented. But they're quite expensive. Only one form of polyethylene seems OK to me: XLPE. Most moderately priced wire uses 'bad sounding' hydrocarbon insulators, in my opinion.

Now a story. In this exhaustive cable journey I faced a 'crisis of reference' - too many variables with too many unknowns and interactions - functionally non-analyzable. I contacted Ray Kimber for a chat, citing specifically that magic Black Pearl wire that had been part of Thiel Audio since the early 1980s (with upgrades along the way.) Ray suggested that an impeccable reference would help and I agreed. My working sample is 5' (2' tweeter and 3' woofer) in the SCS4. So he sent me a couple of samples including his Silver Stealth Magneto, and Copper Gyro-Quadratic series, both in virgin clear teflon. They use open braid geometry with the central air core as the optimum dielectric. Magic. I can't afford it for my present Thiel Renaissance vision, but it did its job of establishing a neutral, detailed, problem-free reference. I suggest Kimber to be on your look list. I'm glad to compare notes behind the curtain.

Cable is a wild ride. If anyone tries to make the case that it doesn't matter, ask them to listen. Not only do these differences show up in measurements, they fit with what the physicists know. It's computational feasibility that requires combining causes to reduce effects into a LRC formula that can be easily interpreted. But we hear the issue of the complex causes, not the simplified summaries. Enjoy the ride.

bonedog - you have the right driver. I'm working from memory of 35 years ago and I have 2 originals here. Light gray surround matches paper cone color. 13M Thiel-8521.

JAFant - Nothing very fancy, but chosen for neutrality and high value.I did indeed buy the Thiel Audio Sony ES SCD-1 at auction. It played a few discs beautifully and then failed. Long story shortened, I want to sell it with its upgraded internals and a back-up NOS laser to someone who can deal with it. PMs welcome.
My workhorse is a PS Audio Stellar Gain Cell DAC/Preamp which accepts digital and analog inputs, with balanced, RCA or headphone output. Nice, flexible, affordable unit.

My CD player is Thiel's original Philips CD-80 which was their flagship in the (1985?) day. I use both analog and digital output. It holds its own in comparison with some newer, pricier stuff - and it's what I have and have known since 1985.
My turntable is a Rotel LP900 with a decent Ortophon MM cartridge. The Classé DR6 has a decent MC/MM phono preamp. 

I store downloads on a SS memory card and play through iTunes or Audacity on my MacBook Pro using USB out to the PS Stellar. Audacity supports up to PCM 24/192kHz. These days most of my production session evaluation takes arrive in the form of emailed files or on a USB stick at 24/96.

The lion's share of my everyday source material is RedBook 16x44.1 CDs. Part of that is because I track producers, recordists, mixers and mastering houses to have a better idea what I'm listening to. I make notes on the jacket. And the CD-80 has good remote control and time code for easy A/B and recall.

I know this old-school and entry level stuff is less than impressive to most audiophiles. But it works for me, and I've never been embarrassed when comparing against other gear. But of course, there is something in the works. PS Audio is introducing a PerfectWave SACD player that plays everything listed above plus SACD as raw DSD out via their I2S cable to the Stellar converter. That will give me universal high resolution capability, which I have wanted for years.

Thieliste - I don't have 3.7s, but can speak in general to your listening angle question. I believe the biggest factor is the room. Jim designed all the floor-stranders to be fired straight ahead if the room can support that. Their cross points are unusually low to better balance the in-room power response with the on-axis direct response. Add the fact that drivers usually have some hot-spot beaming directly on axis - their smoothest response is around 15° off axis.

That said, nearly everyone uses them with the focal point somewhere behind your head, perhaps 5 to 10° off axis. Notable exceptions include the Thiel listening room and Tom Jung's mastering room with CS5s. Thiel speakers with their long, slow roll-offs exhibit less than perfect FR graphs, which are decidedly smoother and flatter at 15 to 20° off axis. I believe the discrepancy is that most rooms have side walls too close and too reflective to properly support Thiel's wide polar pattern. Those reflections are more onerous than the FR hot-spots on axis.

I suggest that you might try bringing the speakers closer together, perhaps 7' or even 6' C to C, and fire straight or nearly straight ahead. A 10' from baseline listening distance puts your listening angle at the 15 to 20° sweet spot. If the sound is less harsh when toed in, try instead putting some absorptive or diffractive material on the mirror-spot on the side wall. At best you can get greater image width, solid center fill, and smoother frequency response with no down-sides.

I realize I'm going against common wisdom that the wider the stance the better. In a large room like Thiel or DMP, you can get both. 9-10' spread and straight ahead with 12' listening distance approaches ideal in my experience. But smaller rooms reduce possibilities. In my opinion, most people toe in when the might be better served by narrowing the stance.

unsound - the rubber pads were to add mass to lower the resonance frequency. Turned out that the center plugs did a better job of that. There were also some motor improvements. That's when Jim was getting his legs with FEA for motor geometry and all that.

And he used the Goertz flat wire, which has the lowest characteristic impedance, which is a requirement for very low impedance speaker loads.

Dspr - CS5s are a tough nut to crack. Their impedance drops to 2.5 ohms at 150Hz and keeps dropping to 1.5Hz by 20Hz, and lower at 10Hz. It devastates most amps. I don't remember for sure whether the 'improved' woofers raised that impedance a little. The CS5(i) did not prosper in the market because so few amps could drive it well. As you know, Jim used Krell, ending up with the FPB-600 which could drive a tank.

OK, not petty. I'll look into it.

Regarding driver wiring: there is a simple trick if you have a multimeter. Get access to the driver terminals, feed a signal to the speaker. Measure the AC voltages at the terminals. The woofer should be the highest, midrange much less and tweeter less than that. If a tweeter shows higher voltage than the mid, it is mis-wired from the crossover. Get Rob’s help to straighten it out.

Regarding cabinet construction. Thiel speaker walls have always been multi-laminates. Solid woods are less than desirable due to variable, under-damped and unpredictable resonance modes. The outer layer is a face veneer, matched by an interior backing veneer, each about 0.020" thick (5 pieces of paper). The 3.7 and 2.7 share their substrate panel which is an engineered sandwich of birch and other veneers glued into the curved shape under heat and pressure. In a historical context, that sandwich was envisioned from the beginning; it just took time to develop into a real product.

In the 03 development in 1978, we landed on Baltic Birch plywood as the substrate. (In fact we used FinPly, a higher quality alternative.) That BB/FP is twice as stiff as Particle Board and 3x as stiff as MDF. But it is under-damped and unpredictable in its resonance modes. Over the years, I messed with making our own build-ups, including bending the panels, which solves most of the inherent panel movement. But, for a small company making moderately priced products, those technologies were beyond our reach. The CS2, 3 and 3.5 used 1-1/8" industrial particle board plus face and back veneers for an extremely rigid and well damped panel. When we developed CNC capacity in the late 80s, we converted to MDF because we could pack engineered shelf braces into the construction. Check out the cutaway in the Stereophile review of the CS2.2, which was our first product designed for CNC manufacture. Nonetheless those well-braced MDF cabinets exhibit some resonances, and quieter is better. For the 3.7, Thiel found a subcontractor in Atlanta to make the unfaced custom curved panels. Thiel added the face/back veneers in-house with a custom curved mold press. That same panel is trimmed for the 2.7. The precision machining, including landings for the internal braces, were done on Thiel’s custom CNC.

Regarding drivers - Thiel designed its own drivers beginning in the early 80s for the CS3 introduced in 1983, as co-developments with Vifa of Denmark. Our deal was that Jim would design what Vifa could manufacture and offer to the larger market to amortize their development and tooling costs. That was unique in the industry and many Thiel design innovations worked their way into generic Scandinavian offerings. When our requirements eclipsed those of the broader market, we had to create our own driver-making capability, not because we wanted to, but because that was the only way we could get what Jim wanted. The CS5 (1989) drivers were (modified) off the shelf, except for our exclusive UltraTweeter. The following CS2.2 and CS3.6 were completely Thiel-designed x Vifa-made for us exclusively. All further products’ drivers were built in-house. By the time the 3.7 was designed in the mid 00s, Jim’s illness had progressed, and ways were developed for outsourcing most critical parts. Thiel, along with Vifa, ScanSpeak and others, co-developed FST as a high-quality Chinese driver source. Things change, and FST became the only feasible way to make those custom flat diaphragms. Many of the high-end Scandinavian drivers are coming from FST and other Chinese suppliers. Most of Thiel’s products since the mid 90s have early drivers built in-house and later drivers sourced from FST. In most cases they are equivalent, but in some cases, like the PowerDriver in the PowerPoint, etc. the tweeter module can no longer be replaced separately. Thiel could pull off that stunt in-house, but FST insisted it couldn’t be done. And you can’t make a supplier do what can’t be done.

From a historical perspective the 3.5 > 3.6 transition is a watershed. The 3.5 has the more "correct" sealed box bass response. The model 2 was invented to implement the less expensive reflex bass. That introduces phase / time lag at the bottom of the spectrum, but the model 2’s reduced budget admitted that trade-off. Our pipe-dream vision of the model 3 was to develop a subwoofer that matched the second order sealed roll-off model three bass and which, by careful placement, can be made time correct and phase benign.

Around 1990 we had entered a subwoofer development project with Vifa creating a very early class D implementation. That should have become the bass foundation for a breakthrough 3.6. Another intriguing option was a transmission line bass, but at that time adequate modeling was not extant, and TL bass included tons of guess-work, trial and error and mixed results. An improved equalizer option was also floated as an intermediate step between acoustic and subwoofered bass. Through a few years of significant grief - that subwoofer didn’t materialize - it took years too long to develop. The market demanded a new model 3 offering, especially in Kathy’s opinion. Without putting too sharp a point on it, the 3.6 with its reflex bass became the result. Its bass is quite well executed, some say about as good as the form gets. But, it’s still a reflex bass system with its limitations and trade-offs.

I’m somewhat surprised that Jim continued with the reflex bass in his subsequent higher-end products rather than building on the seminal work of the sealed CS5, as well as developing transmission line and/or including subwoofer augmentation. A one-man development team can only take on so many challenges.

I second what's been said above. The 3.6 is the more mature and accurate product, plus it can be maintained with available rebuilt drivers.

Yea - you get what you get, and it gets better. Burn-in is relevant to reviewers to assess what a real listener will live with over time. I would love to hear if you find any measurable differences between fresh and burned in.

Sorry I missed your humor. Let's call it a CS4.

Beetle - I'm not sure how much of that is correct - coming from different sources over time. I said mechanical crossover, but was enlightened to the contrary. Also the carbon diaphragm idea was countered by machined aluminum / beryllium alloy. And the sealed bass might have been my speculation based on my knowledge of Jim's fundamental bias. I never spoke with him about it, and my input comes from three sources with their own reads on the prospects. Even though his illness was kept secret from all of us, he knew he was dying; so the 7.3 may have been mostly speculative. But it seems it was what he was working on at the end.

Mdiaz - you are not alone. "Brightness" seems to be Thiel’s Achilles Heel. And saying it isn’t so can bring ire from non-believers. Critical consensus places Thiel as quite flat in response, without the common high-frequency droop, and Jim was adamant to not fudge the response to make them easier to take. But there is real stuff going on there, and that real stuff is central to my present work with rehabilitating classic Thiel designs.

I have developed a long list of upgrades that serve to tame that perceived brightness, and that work will see the light of day someday. But I must say that my first and largest recommendation is to work on your room. People say it, they say it here, and elsewhere, but it is hard to believe how big a deal it is. The reflections and chaos are often full-range, but the most obvious and irritating band is in the lower treble brightness range. About a year ago I spent a couple of weeks chasing weirdness in my playback studio, and when the dust settled the sound was so much more articulate, relaxed and alluring that I barely believed I was listening to the same system. This mitigation work is tedious and lacks the glamor of buying new equipment, but man is it cost-effective and satisfying.

But, even if your room is nearly perfect and you’ve chosen mellow gear, and you avoid over or poorly produced recordings, Thiel may still be too close to bright and forward for your tastes. I am certain that I am identifying causes and crafting solutions. I’ve mentioned some of them in this thread over the past couple of years. There are more. For example, right now I am working with wire. Thiel used an aerospace-grade top notch wire, and that was as far as we took it. Jim would settle an issue to his satisfaction considering hardcore science with listening verification, and then put that inquiry behind him. There is only so much bandwidth available if a one man design house wants to keep breaking new ground. But, I know that he did not consider the transmission line propagation anomalies in the wire runs, nor some of the subtleties of EMF interactions. Indeed those models and science were not very accessible then, and even today remain obscure and fringey. But they are real and sonically consequential, even if not thoroughly understood or modeled. A new wiring harness will be quite different than stock Thiel 18/2 solid in teflon. And there is always more. And as I've mentioned before, I believe the ear-brain is qualitatively more critical of such problems when presented with a phase coherent signal which it accepts and scrutinizes as 'real music'. A book could be written about that. 

Brskie - it would be good information for all of us to tell us what your previous system was, what you changed to, and what specifically you hear. Just a request to help calibrate us on our journey. Thanks.

Beetle - thanks for the link.Tmsrdg - I'll speak to the geriatric speaker problem. Yes, there are concerns, but not very centered on ageing of materials in Thiels. We paid lots of attention to longevity, our finishes have ultraviolet screening agents, driver surrounds are rubber for very long life, etc. If someone places the speakers in direct sun without the grilles, there may be some hardening/stiffening of the surrounds to raise resonance frequencies. I suggest keeping them out of direct sun and with their grilles on.
The main concern is fatigue of the tinsel leads in the drivers. We spec'd really good braided leads, but they eventually fail, especially if overheated. The CS5 drivers are presently serviceable via CoherentSource Service and/or their manufacturers. Work is being done to stabilize that service into the indefinite future. The other potential vulnerability is crossover capacitors. The CS5 is pretty bulletproof. Almost all of the caps are film, primarily film and foil, which have extremely long lives (indeterminate.) There are only 6 electrolytic caps, all in parallel shaping circuits, so their failure would be quite benign. Thiel used ultra high quality electrolytic caps with a rated service life of 40 years - but speakers generally are used far less than service ratings assume. As mentioned in the bulletin Beetle attached, storage is an electrolytic cap's worst enemy. Another hazard of old electronics is solder joints. The CS5 was when we chose Alpha's SAC305 solder which is used by NASA for space duty gear. I've never seen one fail, but retouching those hundreds of solder joints would increase peace of mind.

In short, I think that age is a problem in old speakers, but much less of a problem in old Thiels because we considered longevity in our mission. 

Brskie - good to meet you. Your point person is Rob Gillum at CoherentSource Service who worked at Thiel from 1988 through the present. It seems to me that there was a coax driver upgrade that people considered substantial and a couple of XO mods to accommodate it. Rob would know.
Beyond that, I am not working on the 2.3, but we could apply the general solutions we've found which include Mills MRA-12 resistors and ClarityCap CSA caps, especially in the coax feed position. Others here have done it and we recommend it for a DIY project. 

Fitter - that’s a very good question; and it deserves a bigger answer than we can provide here. Let’s start at the end. No, an assembly-line wouldn’t help. Let’s also start with some apology in the philosophical sense - on what do I base my summary assessment. Short answer is experience, longer answer includes lots of work through lots of details, and I suppose we might include that I presented these conclusions at International Woodworking Fairs, a manufacturing convention that alternated between locations in Germany and the USA.
The problem of mass-assembly goes back to the industrial revolution and revolves around the nature of human enterprise and labor. Modern production methods try to simplify and comodify labor with a hope to replace it with a machine operation for lower cost. Such a strategy assumes many things including the wish to treat labor that way, and also the large quantities required or desired to pay back the investments.
Thiel Audio wasn’t made that way. We were a company who sought to provide good livelihoods for good people making good products for good customers. You can substitute the word right for good and land close to the Buddhist concept of right livelihood. Big discussion, little time.
But on to some practicals. Part of your question might include how little seemed to be accomplished in the video. I can assure you that video was made in an empty factory in slo-mo for the sake of clarity. I like the video; I had not seen it before. Rob Gillum made a sneak entry in the finishing room, and I hired him and one of the other guys in the 1980s; they’ve been part of the story for a long time. What a trip. Let’s visualize those production spaces with 20 to 35 busy, skilled people populating them, moving like they know and care about their work. Our productivity factors were world-class.
Now let’s touch on some history of small-unit manufacturing at Thiel. In the beginning Walter Kling and I created a medium batch manufacturing process, limited by physical shop space. The 01 and 02 were made in batches of 40 and the 03 in batches of 20 because the first shop wouldn’t hold any more than that. It looked like a small, crude but effective line in that each person tended to do the same operation to whatever speaker was coming past him. With four standard wood finishes plus a half-dozen optionals, those runs were always a blend of back-orders and speculation for who might want to buy what. You might see a problem brewing here. If we had Walnut available, someone would want Rosewood, etc., and everything unsold had to be stored. When we moved to Nandino Boulevard in 1981, that batch number increased to 100 and then to 200 as space increased. Now add more products and more finishes and dealers who sold to the taste of the customer and there are, let’s underestimate, more than a dozen finishes x 5 or more products. Do the math. So the work of the early nineties became developing an effective and efficient production method with a batch size of one unit or pair. That story is deep, wide and long, and includes Vifa as well as worker skill sets and longevity, and labor and customer payment schemes. It’s a good story for the book. Remember the book?

Unsound - good presentation! I would like to start by saying that I love the 3.5 and barely know the 3.6. My comments address the arc of development of ideas into products at Thiel. Regarding measurements, JA’s rig at Stereophile has value for non-coherent products, but like Rich V and John Dunlavy, Jim called out JA on how his ’nearfield’ rig did a disservice to our products. Jim did his calling out in private.

My comments about product maturity and accuracy are more from a perspective of problems addressed and solved behind the curtain. Each product was a closer approximation to Jim’s stated goal of the four faces of accuracy. We invested heavily in building a new measurement lab and equipment with each of our moves and expansions. By the early 90s Jim had his final lab setup which generated measurements that track with the Canadian National Lab and other heavyweights. They told the story. Those measurements coupled with a pretty deep dive into Finite Element Analysis revealed layers and forms of distortions that were each formulated and solved, as well as practical, within the framework of the next product being developed. My lightweight measurements here show the 3.6 to be technically better than the 3.5 in all ways except the bass. But that leaves much important ground unturned.

The CS3/3.5 was developed with less robust lab resources and before FEA. I think of it as Jim’s masterpiece because it showcased his resourcefulness and resilience. I’ve mentioned measuring speakers in the tree and the rooftop and buried in the sandbox with his self-designed and home-built sweeper and bleeper and hundreds of hours of critical listening. And on and on. The 3/3.5 stood on the shoulders of our previous more homespun efforts. And it shone brightly and made us proud. I have not previously addressed the heart-wrenching difficulty of abandoning the sealed bass and how that came to be.

Our first marketed product was the 01 in 3 generations, with a sealed, equalized bass hitting 30 Hz in a bookshelf format at 92dB sensitivity. That bass system was his pride and joy, resulting from more than a year of experimentation with sealed, vented, transmission line, plus some flights of fancy. We expected that bass system to continue forever. But the market pushed back pretty hard, considering the equalizer as a Bose copy or like waving a red flag in front of an audiophile (Larry Archibald in Stereophile), Harry Pearson spending half of our virgin 03 review in the Absolute Sound picking apart the negative sonic impact of the EQ. Etc.Short story is that the 02 with its ported bass, which we considered less than best, was conceived in that push-back. I’m with you regarding the vented bass of later Thiel speakers not fitting the philosophical construct of coherence. But notice that the reviews and marketplace at large rarely if ever denigrate the 4th order time lag of Thiel vented bass. They mostly praise its ’punch & solidity’. So you and I and a few others can appreciate the ’rightness’ of the sealed/ eq’s bass, but that doesn’t build a company.
I’m not surprised that you appreciate and enjoy the CS5 and its sealed bass. That was JIm’s attempt to execute correct bass down to 20Hz without the maligned equalizer. And it works extremely well with the big IF surrounding amplification requirements. These days I take some flights of fancy regarding other roads not taken. I believe that those roads, closer to Jim’s and all of our hearts of our specific, eccentric interpretation of how to best reproduce music, could have led to a more satisfying and ultimately meaningful life’s work as a designer and a company. Consider that the later drivers are far more efficient than the CS5’s and how that would have permitted higher impedance configurations to allow far more kindness to amplification. Jim’s dedication to developing the CS5 was monumental. His and all of our disappointment in its tepid market reception was close to devastating.

Now we have two seminal ideas of equalized and unequalized sealed bass which both met more resistance than acceptance. I absolutely wanted to improve those platforms. Jim was discouraged. Kathy as marketing director surveyed the landscape and decided (she was the decider) that ’it didn’t make much difference’ to the dealers as long as it sounded good. We could spend a chapter parsing that out; but bottom line is that Jim abandoned his signature bass approaches and focused on executing vented bass the best he could.
I’m glad that you are addressing these issues. They were huge issues for me personally. My gig as a founding partner was to incubate the company to sustainability while keeping our vision clear. I deemed the bass alignment thing to be a core issue. Kathy did not. Jim and Kathy, by that time, marched in lock step.

There is another significant issue around company building. I’ve mentioned before that we bootstrapped our growth, which is an understatement. By CS5 time (1988) we took on a seasoned business manager who worked the numbers hard and well. His assessment indicated that we were underselling our products by a LOT and couldn’t continue. A fledgling company can do the near impossible at a small scale for a limited time. We were ten years in and technically not profitable. Another chapter there. Suffice it to say that getting great bass can represent over half the cost of an entire product (bigger cabinet, serious drivers and crossovers, etc.). So your price comparisons should consider that the CS3 and CS5 iterations were selling at unsustainably low prices. The watershed product that distilled these conflicts was the CS3.6 with its vented bass, executed very well, but nonetheless a compromise.

You may appreciate that I never bothered to listen to a CS3.6 after its production development rigors. Isn’t life something? Some issues and developments only come into focus through a very long lens. That’s been more than 25 years ago. Thanks again, John.

What little I know about Adcom. In the day, Adcom may have out-sold everything else put together - solid entry into high value high performance. I knew Nelson Pass at the time and he designed a few of their mark I products. The updates and mark II versions were not designed by him. In his (paraphrased) words: "I would design a simple, clean, straight-forward unit, it would have its market life and then they (Adcom) would hand it off to someone else to pile on the parts." He said he had nothing to do with the GFA555mkII. It was designed by a well regarded French designer with considerably more complex circuitry and feedback schemes.

Fast forward: I contacted Jim Williams regarding upgrading my 555mkII. Jim rebuilds and upgrades professional studio gear out west, considered about the best it gets. He upgraded my Studio Technologies mic preamp that I got from Tom Jung. Jim picks only gear with solid upgrade potential into the big leagues. The improvement in the mic pre was stunning in every audiophile respect as well as textbook measurements. This is all to say that Jim told me he doesn't work on 555mkIIs - he doesn't really like them. BUT if I sent him an original 555, I would like what he sent back.

Two points: 1: don't assume a later amp in the line is the same. 2: If you stumble on a good deal on an original 555, snag it, for yourself or me. I would have it delivered to Jim Williams and eagerly await its arrival in my hotrod garage.

Unsound - good horses keep living and living. Your judicious explication reminds me of a general theme which our Goners might enjoy. Thiel presented a peculiar problem for many retailers, including Innovative Audio. Retailers make packages. Those packages follow guidelines or rules. In the day it went something like one third budget for source, a third for amplification and a third for speakers. Give or take a lot. Thiel comes along and the formula crumbles because Thiel rarely sounds very good with an equally priced amp, and someone with twice the amp budget is inclined to believe that a speaker at twice the price of Thiel is better for him/her. (Most often him - often her perspective permitted the Thiel, damn the formula.)

Jim had no patience for what he considered such illogical behavior. His formula was that lower prices make easier sales. He also fought to lower prices, especially at product introduction, with unrealistic and ill-founded ideas of how costs would fall as production rose. In fact the opposite was true, but that’s a different story. But the fallout was that just as the retailers settled into their Thiel pricing / presentation strategy, the prices would rise significantly to the consternation of many dealers. The joys of sales rival those of manufacturing. LOL.

Audio Consultants in Chicago broke the mold splendidly. They set up Thiels in multiple rooms spread over multiple stores so that customers could hear $2500 speakers driven by $10,000 amps and understand that the whole budget was well spent. AC was our top dealer year after year.

thoft - completely different, higher order, reversed polarity tweeter. I'd love to see time domain plots.

Robert - a primary consideration is the length of your interconnects. Long interconnects place the burden of driving them onto your source components.