Dsper - I have long experience with CJ and McC DNA - both are excellent in my opinion. Be careful not to confuse tonal color (CJ=dark) with a perceived problem (bright treble at high volume.) A sweeter preamp might make the problem less evident, as might a different speaker, but the problem has not been addressed.
I suggest borrowing some cables before inserting your CJ, since you know your existing system well.
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Offering a third to Harry's second: All the early spikes are the same. Thiel "invented" spikes in the late 70s for the 03. If others were using spikes at that time, we didn't know about it. Remember, no internet. They were all the same 1/4" x 2" with free 1-1/4" available by request for hard floors. I don't remember when we added the friction O-ring and grip grooves, but then they all became that way. The exception was the 1989 CS5 (? and probably up-market models after 1995?) The CS5 was too top-heavy (and therefore potentially dangerous) for three-point support. We replaced the recessed plinth with a full-footpring base with 4 threaded pins on the corners. That pin is ø 5/16"x18 tpi with 4 wrench flats for adjustment with the included 1/4" wrench. Zero clearance, tight tolerance fit keeps the cabinet from squirming. The holes in the hardwood base are also threaded to supply resistance and obviate the need for a lock-nut. Fun with minimalist elegance both for these threaded pins as well as the normal slip pins where 3 points defines the plane and requires no adjustment.
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CS3 lovers - just saying that the CS3.5 is really a CS3 with more sophisticated drivers. Same concept, functionally same cabinet. Any future life we develop for the 3.5 will apply to the 3. We have a good midrange replacement candidate. A replacement tweeter will be easier to find. The woofers are battleships and repairable.
The real issue with the equalized sealed-box 3s is that the boosted bass can bottom the woofers, and also puts real strain on the midrange. I am working toward keeping the sealed bass as-is (unequalized) and augmenting with a subwoofer crossed over to match the natural second order bass roll-out. That frees the 3 drivers to operate in their natural range for lower distortion and longer life. I now have a pair of CS3.5s, and they really are quite good, especially for 1983 (CS3) and 1985 (CS3.5).
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PW - I am all ears for as much detail as you care to share regarding your auditioning. The Crossover Upgrade Project is addressing all aspects of crossover performance. Jim's CS2.4 Signature Edition significantly upgraded tweeter feed capacitors, which certainly affect the entire midrange clarity. Our work will replace those ClarityCap SAs (then state of their art) with CSAs which are considered significantly better. Additionally we will be CSAing the upper end of the woofer, which certainly addresses the lower mid-band (I can also afford to lighten mine).
Update: I now have in-house all the ClarityCap CSAs and CMRs along with RTX and Cornell Dubilier styrene bypasses and 4-9s wire and foil coils to build out the PowerPoint, CS2 2 and CS2.4 prototype crossovers. My test mules are my PowerPoints and CS2 2s before we take on beetlemania's CS2.4s. I have two levels of upgrade specified for each of those first two products.
I am listening closely to the collective listening experience of the various forums, to augment reviewers and my personal experience. All are welcome to chime in regarding their perceptions, especially of two-series products. My available time is a distinct limitation, but my interest in the Upgrade Project continues to grow.
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In a new twist of priorities, the SCS4 has come up on my radar.
It shares a driver & XO basics with the PowerPoint, my first project. The SCS4 has a crossover for Thiel SmartSubs. Any interest out there in A'gon Land?
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Beetle - the CDs are being considered for bypasses in the woofer shaping circuits. As PolyPropylenes they are less expensive than the PolyStyrene RTXs which will provide more detail in the upper range.
I am reaching for a level of finesse beyond what Thiel aspired. Development of the final voice will require additional reference amps. I am over a thousand miles from Rob's Krell FPB-600s, and most other heavy-hitters are beyond my reach. I have an opportunity to buy PS BHK-250 stereo or 300 mono pair. Beyond the reviews and RonKent's enthusiastic endorsement, what does this board think of the BHK as a reference amp to balance my Classé amps?
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Ron - thanks for the link. I hope to put a BHK in the voicing mix, probably the 250 to voice toward real-world amps that Resurrected Thiels might be used with.
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Check out "On Golden Pond" which was filmed on Squam. The beauty here is embedded in the mentality and actions of the community.
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Jon - Thanks for the Bryston idea. Indeed Classe DR9 is polite and a little "tubey". Bryston might be a good counterbalance.
Pops - I have never felt the need to better my CS2 2s. I'm looking forward to hearing what my XO upgrade work might bring to the table. Mine are pre-production, custom voiced prototypes, but at 28 years old are nearing their electrolytic cap lifespan. With SpectraFoo, and possibly Klippel, I will be able to re-balance all circuits for the very played-in drivers.
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Unsound - 2 ohm loads suck and amps give up. Thanks.
Jay - The CS2 2 and 2.3 represent a major tide change. The 2 2 uses all discrete Thiel-designed x Vifa manufactured drivers. They are conventional as single-band (woofer, mid, tweeter), although unconventional via Thiel underhung motors, copper motor shunts and so forth. The woofer is the first dual cone (straight-deep x curved-shallow). PP woofer and midrange x Aluminum (CS5) tweeter. The 2 2 was also the first passive radiator which became the new order. That basketless foam core diaphragm sported dual rubber surrounds (front and back of baffle) to maintain linearity without the cost of supporting framework. That geometry convinced Jim to migrate from the (very inexpensive) port to a passive radiator. In many ways the 2 2 represented a coming of age foundational product with seminal technologies.
The CS2.3 is a breakthrough to the coaxial-coincident upper driver. A central problem of first order slopes is driver lobing which makes listener position quite critical in the vertical dimension. (All those Stereophile graphs at 48" to eventually 80" misrepresent the integrated waveform at any correct (more than 8') position at the proper height (34" to 38".) You get the idea; lots of constraints. A coincident upper driver makes those upper integration problems go away, and the mid to woofer transition has long enough wavelengths to minimize actual mis-performance. The 2.3 coax incorporated the breakthrough viscous suspension which eliminated the electrical upper crossover, which could have been further refined over time to become a permanent solution. (Jim dreamed of a triax for true point-source propagation.)
However, as first-generation, the 2.3 coax was not mature. The product had the weakest sales of the series 2 generations with a life-span of less than 5 years against 9 for the 2 2 and 8 for the 2.4. The 2.3 was a watershed / breakthrough product introducing technologies that were improved by its successor . . . the CS2.4 became an audiophile darling.
On a personal note, I was part of 2 2 development; the 2.3 was finalized after my time and its particulars are what I have gathered second-hand.
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The drivers became more rigid, operating more smoothly over a wider band-pass and therefore the compensation networks became fewer and simpler.
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unsound - I agree. I don't know why Jim designed for such low system impedance. I can speculate that marginally lower distortion in the driver motor may be had via lower driver impedance . . . BUT all the amplification problems caused by low impedance are a huge negative factor in system performance. As I've mentioned, he called those problems "amp problems". I don't know enough to speculate meaningfully.
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Most of you have identified phase coherence as a necessary ingredient for "reality music", rather than the hi fi approximation. As far as I know, Vandersteen is the only maker other than Thiel who produces actual minimum phase speakers. Their bias is towards "easier", less "incisive", but they are very good. Please advise of any of these other makers are phase coherent transducers.
Dan - the eventual list includes the x.7s. But they are so much more current that I feel obligated to take on older models first.
I have commented previously on listening position. I understand that any particular room and preferences may dictate many different positions. Crossover frequencies x propagation lobing patterns require those
distances for proper integration. Anything closer or higher or lower may
produce pleasant effects, but will trade off against some of the factors of fidelity.From a scientific standpoint, there is one position that replicates the design goal of minimum phase and flat tonal balance with optimum transient response. That position is minimum 2.5 meters (100"), with 3 meters (10') being a little better with an ear height of 3'±2". The more the distance, the less critical is ear height as well as toe-in.
The coincident upper driver of the x.7s greatly reduce the distance requirement.
Tom
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Insider information: I've been told that Jim and Gary listened to every cap out there, along with measuring to choose the ClarityCaps. At the time the SA was top of the line. I've compared the SA to the CSA. The CSA is next league. Truly remarkable.
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First, thanks for the jostle of other phase coherent brands. It also seems that some ultra-expensive European brands are honoring the time domain. (Reminder: engage brain before responding) Cheers.
Regarding grille and grille frames - they, like other design elements, offer opportunities to address problems. Thiel did so from early-on.
Thiel's O1 had a reticulated foam grille. For the O1a, we formulated and sculpted the foam to be ultra thin on-axis and 1" thick off-axis, which attenuated the bounce wave along the baffle to reduce edge diffraction. The O1b sported an ALD (Acoustic Loading Device) - a sandwiched filter, attached to the grille which was nearly invisible on-axis, but further reduced baffle waves. The grilles were nearly universally derided, disregarded or discarded, even though they improved performance considerably.
The O2 had an "ordinary frame" for a fabric grille, since we learned that audiophiles would remove it anyhow.
The O3 and O3a grilles just covered up felt blocks, etc. on the baffle.
The O4's grille was pretty sophisticated, incorporating a tweeter wave guide, woofer edge-softening profile and port impedance-matching flair. We attached it with serious goo which made it evident it belonged on and ugly when taken off.
The CS2 in the mid 80s got more serious as we increased our precision of acoustic measurement and understanding. The tweeter wave guide became more sophisticated; the wave launch profiles of all 3 drivers were supported by the grille frame, the fabric was engineered for transparency on axis and absorption off axis, and the outside edge was engineered to minimizetweeter diffraction. It was successful EXCEPT that Larry Archibald of Stereophile printed multiple critiques of the "harshness" of the CS2. When we all figured out that he used and measured them without grilles, he re-visited their performance, but never admitted his mis-use as causing his problems. He stated that Thiel had upgraded and mitigated the problems he had heard and reported. Hmmm.
The CS1 series incorporated an even more sophisticated grille for wave launch and baffle vibration damping.
Similar issues prevailed through the years, with the common thread being that users' preconceptions about the harm of grilles persisted. In the case of Thiel products, the grille was always an integral design element. They were in place during development, voicing and testing. Removing them may provide a more immediate on-axis connection, but problems are always introduced which degrade musicality. More recent models incorporate the wave guides into the baffle, and the grille frames are farther aft, minimizing harm when not used, or non-existent. Newest models use perforated or woven metal, which is more transparent.
One of my intended experiments employs wool felt on baffles. We tried that early-on to good effect, but opted for grille fabric and frame solutions as more cost- effective and good-looking. I'll try some soft baffle ideas on my CS2 2s.
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Prof - thank you for your appreciation. The "live with" factor was an integral part of our designs.
Jay - there are two periods of post Jim Thiel designs: the x.7s including the 2.7 and 1.7 and the MCS?.7 prototype. The physical CS2.7 was principally developed in-house by Kathy Gornik, Rob Gillum and Dawn Cloyd in tribute to Jim's practice of incorporating series 3 breakthroughs into the series 2 at lower cost. Part of that cost savings results from minimizing amortization of development costs of series 3 technologies when applied to the series 2. The 2s have always been bargains.
The electrical engineering was done principally by a Canadian consulting engineering company using the Canadian Research Council anechoic chamber and design facilities. I have been told but do not remember the name of that company. A few outside opinions were also solicited, but did not generate material contributions. Serious $6 figures were consumed developing the 2.7, leading to the need to sell the company. The twos had generally been somewhat "easy" since they benefited from the generosity of the threes.
After the sale things happened fast, but of material consequence is that Bob Brown of Boston-area upper mid-fi experience was brought in as consulting operations manager who brought in Steve DeFuria, a long-time Thiel retailer, knowledgeable insider and sales executive with various Boston-area upper mid-fi brands. Bob and Steve hired Mark Mason formerly of PSB and freelance designer for SVS. Mark determined that Jim's phase-time coherence was not important enough to merit the significant difficulties it caused. The new owners wanted to exploit the name and chose to pursue mass-market Chinese-made products.
The 3rd Avenue Series (TT1, etc.) were developed by Mark Mason with help from New Thiel's considerable in-house engineering chops led by Dennis Crosson. The products are commendable for a new market entrant; but the marketplace was flooded with very good ordinary speakers. They spent upwards of $10million doing the dance that many of us witnessed with sadness and chagrin.
Additional factors tied the hands of the new owners, but those remain behind the curtain until answers might come to light. Jim's copious lab documentation is nowhere to be found.
Thanks for asking.
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Jay - when Rob had access to the New Thiel cache when they were closing the Nashville facility, he reported that 3 pairs of the series had been sold. There was inventory, but I don't know how much or what became of them. Rob didn't bite.
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Add to the 2.7 development team: Gary Dayton and Lana Ruth.
The design engineering firm was Warkwyn, Ontario. I think the lead designer was Tim Gladwyn. The 2.7 XO is very different from Jim's 3.7 XO. I hope to eventually learn enough to report on the significance.
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Bray - what is the difference between the SS2 and SS2.2. What is your "late model" serial number?
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Bray - I only know the broad outlines from observations and a few conversations. The SW1 came out in 1997 from work Jim had been doing for about 5 years. That was early Class D and incorporated thermistor compensation and shaping circuitry ; the SW1 (2-10") were made in-house. That product became the SS2 in 2004, also made in-house with the 1,2,3,4 line. The unique design required in-house repair, which Jim performed due to his intimate knowledge of the complex circuitry. Jim was sick for a few years before he died in 2009. Sometime in there Bash/Canada began producing the amps, but it seems there was continual struggle to keep the sophisticated particulars in-tact and supported. When New Thiel took over in 2012, they decided to cease support of the line, by then out of warranty (red flag.) My speculation is that manufacture ceased somewhere between 2009 and 2012. I don't have direct knowledge and I don't want to bother Rob with my learning curve. I am gradually assembling my fact base.
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Unsound - the dispersion at the midrange upper end is narrower than the tweeter's lower end. The wave guide creates some directionality at the low end of the tweeter to better match the midrange for smoother image projection vs frequency. They were quite successful in that the polar pattern is more regular vs frequency. Thiel got away from grilles with frames as addressed above, so that element went away. But . . . the shallow midrange cone was engineered as a waveguide for all the coincident drivers. The deep straight-sided back cone supplies strength when triangulated with the shallow, curved front waveguide cone. Wonders never cease.
brayeagle - I suspect your SS2.2 might have been made by Bash, but I am guessing. I'd love your date of purchase and serial number if you can ever manage the wrestle .
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No. Lobing is inherent in first order filter slopes; it has to do with additive phase physics. If one tried to massage or average the lobed output, it would adversely affect the power response. However, the sloped baffle (rather than discrete steps with on-axis drivers) serves quite well to manage the lobing: the 15° down-lobe launches toward the listener, making a larger vertical window than would otherwise be the case. The combined launch waves from all the drivers blend quite well at 10' listening distance. Closer requires more careful setup.
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bonedog - note that the original CS3.5 midrange does not have a foam surround, but rather a continuation of the cone paper infused with silicone. Be careful what you're using for a reference.
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ish - I am interested in your SW1. Please contact me via PM.
Regarding the boundary management software, I would only be guessing. I do know as you outline, that Jim would not have addressed the problem via EQ. I believe there are patents on what he did which you might search online and perhaps report back to us.
I share your phase control question. I am using physical placement for an approximation of phase alignment. Someone said here that LTE can be use simultaneously with PXO to address phase. My speculation is that since the sub crossover is 4th order (high and low), and therefore adding 360° phase shift at xo, and given the very long wavelengths at those low frequencies . . . perhaps he thought plug and play was worth more than time alignment from a phase control. I don't know. Does anybody out there have any educated opinions?
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Ish - Duh. I believe the SSs are all analog, so delays and so forth can't be easily implemented. For example, dsper's upper and lower mid drivers needed 3/8" and 1/2" time delay which took, if I remember correctly, more than 40 bucket brigade capacitor banks. Huge, expensive and specific to those parameters.
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kdross - congratulations on your CS2s. Thiel made more of those than any other model. It is possible that the loud levels did the damage if fed by an amp with insufficient power to deliver a clean signal. It is unlikely that the woofers or any of the drivers being old is the cause of the trouble. Those drivers have rubber surrounds and generally last indefinitely, unless fed a distorted/damaging signal.
Congratulations also on your Classé amps. Your DRs were designed by Classe's founder David Reich who took current delivery very seriously. David moved on to McCormack and Theta Digital. Very good amps, a great match for CS2s.
The fact that your woofers quit (see below) and you used a low-power (?) receiver at loud volumes points to distortion causing the failure. The old Sony played loud is the probable culprit. (Wires are probably not the cause.)
But there are other possible causes or needs.
One probable root of your problem: both your amps and your speakers contain electrolytic capacitors, which have a definite lifespan of 15 to 40 years. They last longer when in constant use. Polarized electrolytics, such as in your amp, lose their bias, especially when in storage. A likely cause of damage is that your caps are leaking, allowing low-frequency power into your signal path and over-powering the drivers. Tweeters and midranges are at most risk, so your woofer failure doesn't match this scenario. BUT, you could be tending a time-bomb. Inside the speakers you can look to see if any of the small, black cylindrical caps have any goo on them. If so, they are definitely failing. If not, they can possibly wait.
I recommend the following. If you like the CS2s, keep them and consult Rob Gillum about the possible need for XO cap replacement. But, you can hear any problems before they do damage. If the caps are dry, cap replacement may not be necessary.
Your amps most probably need service: including new electrolytic caps. I understand that Classe is back in business and can probably service your amps. That vintage amp in that long-term storage situation is highly likely to have bad caps. Classe can talk you through determining whether the caps are leaking (signal or goo).
In my opinion, your gear is worth salvaging and will outperform the large majority of audio gear out there. Good luck and welcome.
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audiojan - nice system. I do have a reservation about the Bel Canto. The site states minimum impedance 3 ohms. Some class D amps hit a brick wall at their minimum impedance. The CS2.4 drops to 2.73 ohms at 600 Hz. I wonder if you might be running out of amp, rather than out of woofer. Might you borrow a known-to-be-bulletproof amp to see if the bass comes to life?
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jon- Rob Gillum at CoherentSource Service makes the PXO modification to match the Thiel speaker of your choice.
audiojan- your experience is classic: distance from the walls makes for better image and evenness, but those very walls were reinforcing the bass. In your situation a subwoofer makes sense . . . unless you can move the speakers out of the alcove into a more normal, rectangular space.
unsound - indeed. They are pigs to drive well. This year I have read and studied widely, and the over-arching problem of Thiel speakers is driving them. The amps referenced on this forum work and many of those are the amps Jim used in development. Krell fpb, Levinson monoblocs, big Bryston, big CJ, Classe DR. The common thread in those designs is their ability to deliver large current streams at high voltage without distress. Others here have recommended other amps, which are no doubt suitable, but I have not heard them. However, when an amp can't deliver the required current, the litany of complaints arises.
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Just suggesting that particular impedance issue.
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Rob and Beetle - I have also gone back and forth between wire configurations. My observations are similar to both of yours, the parallel configuration seems to add dimension and space. I hear more lucid harmonic detail such as obviously double strings on the mandolin or transient fingerings within electric guitar chordal work. And more lush and detailed (at the same time!) mid-bass. Such observations hold true blind.
I have also done some measuring. The only obvious difference is the presence of large, broad "bloating" of sub-sonics, perhaps 10+dB at 10 to 20 Hz with frequency sweeps beginning at 0 Hz, with accompanying group delay anomalies.
I am in conversation with Steven Hill of Straightwire as well as a knowledgeable physicist, plus my reading. Those expert opinions concur that whatever pleasant effect we are hearing, the technicals are more problematic. In other words: "don't do it".
One interesting trial was controlling the separation of the ++ and -- cables. Consistent separation is a technical requirement. Separating at 1.5" (my convenient wood blocks), served to lessen the "effect". Also spiraling the two cables lessens the effect. And, conversely, the effect is pronounced with widely separated runs (1' to 3' along the 10' run.)
I am getting some double helix wire from Straightwire where 4 conductors will carry the signal in star quad (opposite corner) configuration. This configuration is standard practice in studio cables, house wiring and industrial practice.
For my own listening I would choose the separated parallel conductors. Thank you Rob. However, my upgrade work requires science based solutions. I'm still working on the problem.
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The 2.4 and 2.4SE share identical drivers and circuits. The only difference is the sophistication of the feed capacitors for the coax driver. That PXO is the one you want.
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Jan - I hope I am not dominating this forum, but I enjoy sharing what I've learned. I have compared single and stereo SS1 and SS2 subwoofers in my studio with PowerPoint 1.2s as room mastering monitors. The stereo pair presents a decidedly more believable image. Note that the PPs cross over at 80Hz, which includes more upper information than many applications.
John Schwenker - I am intrigued by your second-order experience. Soon I will have my Metric Halo ADA rig back up and will devise a second order XO at 80Hz for low and high pass. It has a high probability of better transient performance than the PXO solution of 4th order high and low. I will be able to measure the net output to ascertain that the subwoofer can produce that 12dB roll out. The PPs produce a textbook 12dB roll out. BTW: second order slopes share some prestigeous company.
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Beetle - I suspect the "don't do it" is because the spuriae introduced are evidence of non-linear behavior which can cause problems for some amplifiers.
Rob - the only resistors that benefit from upping are those carrying current, which are in your stock pair. Plus a couple that I can advise on a PM.
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Ken - my answer to your PM bounced. I give them a high likelihood of success.
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Rob - caps always improve via parallel smaller values. Jim never went over 100uF.
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ish - I would be speculating as well. I have heard that the SSs stay out of the digital domain, therefore accomplishing their requirements in analog, and probably doing it such as you suggest. I can offer no real insight. However, I am still looking to develop a qualified repair station for SmartSubs. I welcome any input from all of you.
Silvanik - Rob at Coherent Source Service does have a CS3.6 XO schematic which I developed from layouts. Rob determines how he shares that proprietary information. We are developing upgrades to address issues such as you mention. Electrolytic caps do drift and fail over time, and there are more sophisticated solutions available today, especially capacitors. I have bought a pair of 3.6s to put in queue behind the PP, 2 2 and 2.4 presently under development.
We have determined to replace all resistors with Mills MRA-12s at unity value for a stand-alone, cost-effective upgrade. However, further changes to layouts, foil coils and lower ESR caps may require tweaking those resistances at the time of further upgrade. The 3.6 work is scheduled in 2019.
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Rob and Erik - The 400uF electrolytic is in series feed to the midrange. Bummer.
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Sil - I like your choice. It is where we landed after considerable study.
I and beetlemania will be posting progress on this forum. As the solutions become finalized, we will set up some form of communication through CoherentSource. But for now, just stay tuned here.
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One Thiel-related thought. That amp is rated for 4 ohm minimum impedance. Your CS2.3 rides around 4 ohms over much of its range, but drops to 3 over a broad area from 100 to 1K Hz, and touches 2 ohms at 400-500 Hz where there is lots of musical content. See the Stereophile review. If I were throwing that load at that amp, I would seek real hard-core knowledge and experience. More to the point, I would default to believing Classé, and not burden that amp with that load.
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tmsrdg - for what it's worth, you might offer those 2.2s to this group first. I know it's all vaporware until we have real upgraded speakers for comparison and review, but I anticipate significantly better sound from the new hot-rodded 2.2s.
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Todd - Hard to imagine, indeed. The x.7 drivers are really something special, plus all the accumulated knowledge / growth in the functionality of the enclosure.
michael - very true. The power hunger is, in my opinion, the primary limiting factor to musical performance for Thiel speakers. I was very surprised how much better the Krell FPB-600 performed than the 300. If a new entity emerges to take Thiel designs into the future, I would explore replacing the voice coils for 4-ohm minimum impedance in the extant motor structures and crossover topologies. I believe the trade-offs would be solidly net-gain. Presently, only a few very expensive amps do a good job. All the complaints like "wimpy mid-bass, unauthoritative deep bass, congested crescendos", etc. are symptoms of inadequate current delivery. Buy the high-current amp. What are you considering? I am considering the PSaudio BHK-300 pair to contrast my Class´DR-9 pair.
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Thiel's first stable of amps included the Phase Linear 400, designed by Bob Carver. I am interested in how the Sunfire 300 holds up. The design orientation and specs certainly fit Thiel speakers' demands.
Next amp was Nelson Pass' Stasis 500 with world-first (to my knowledge) dynamic bias. Those amps do the trick.
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brayeagle - Yes, the Bryston amps have been part of Thiel's history since early-on. We had 4Bs in the day. I hope to find the right model at the right price.
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Todd - you are correct. My needs are somewhat different than "best sound I can get". I hope to assemble a small stable of amps that would be paired with Thiel speakers and are different from each other in sound and topology. And I have to find them at bargain prices.
My old Classe DR-6 x DR-9 pair are known entities to me, heard on lots of speakers over many years. And I've recently added bypass caps and better internal fuses. Their power is moderate and I can use them as monoblocks or in stereo, single or bi-wire to check speaker performance various ways. They function as my humble reference.
The BHKs would provide considerable "tubey" detail and delicacy for comparing the bypass caps, x-checking tonal balance, transient decay, etc. The ear-brain sometimes isolates better with differing signals.
Thiel is often paired with Bryston and I will be shopping for a mid-priced Bryston setup to round out the bipolar landscape. Additionally, I'll be able to cross-check with Rob's Krell FPB-600, MLs, etc. Again, my intent for my working rig is to find amps in the middle price, Thiel-league range which strive for neutrality, but express different strengths than each other.
General riff for weekend fun:
In speaker design, there is a trap whereby one might think one has a particular problem, but by changing amps, cables, etc. the problem goes away. To the extent the speaker can perform well, the problem actually must exist elsewhere . . . or the speaker is exacerbating some problem in the drive-train. I am looking very closely at those exacerbations, looking for ways to mitigate their deleterious effects without sacrificing any of the clarity or incision inherent in Thiel speakers.
I know this is a very tall order, and I am proceeding cautiously. So far, we have gotten worthwhile results from Mills MRA resistors for short cost increase. Foil feed coils also decrease dynamic distortion. They are quite expensive and will probably be used in an upper level upgrade in conjunction with original Thiel 4-9s wire coils, or to replace more recent Chinese coils. Stay tuned.
Caps are a very big deal. Lots of potential for lots of cost. I believe that the so-called parallel-shunt circuits are practically indistinguishable from series-feed circuits, since the circuit is AC and the driver is fed alternatively from each pole. The big electrolytic banks in the shunts are very expensive to replace, but I want these upgrades to result in "permanent" solutions, which electrolytics are definitionally not.
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rules - I love the 3.5. My decision to not include it in my upgrade program is based on lack of availability of drivers or a solution for modernizing the equalizer and the inherent bass-response limit for "modern" recordings.
The product history and back-story is beyond the scope of this post. But the 2.2 in 1990 tested the adequacy of the passive radiator to extend bass response (depth and quantity.) The 2.2 succeeded and Thiel took that path.
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I think a little shot of history might be in order. Let’s look at resistors for a glimpse into Jim Thiel’s working ethos. Of huge importance to Jim was that of balanced design. He worked toward a performance plateau where all elements worked equally hard and efficiently to perform at maximum cost efficiency as a whole system. Let’s look at resistors as an example.
In 1977 we were struggling with the 03 - EVERYTHING was audible with phase coherence, and we wanted to upgrade all components; but we also wanted to keep our focus on cost effectiveness. Jim "built" some reverse-wound resistors from OFHP aerospace copper coil wire. Obvious improvement. Judged unaffordable. Audio grade resistors either didn’t exist or we didn’t know about them. Jim went to work with (what later became) ERSE and developed the present Thiel resistors. They are not "dime store resistors" although they look like them. They are actually made from good wire with reverse winding for a low inductance load, set into a ceramic tub for greater dissipation than a cylindrical case. It costs a fraction of the Mills and performs quite respectably. Balanced design.
That was Jim’s approach. How do we get most of what we want and pay a fraction of the cost. He was proud of those resistors; the early versions said "Thiel" on the case. You can buy that design from ERSE. They outperform normal sand-cast dime store resistors by a long shot.
That said, the Mills MRA-12s are better. BTW: the ones that Jeff Glowacki at Sonic Craft sells are the best. (Not just salesmanship.) I would replace the Thiel / ERSE resistors as low-hanging upgrade fruit. BUT there is a BUT. The MRA case is quite a bit smaller for a lower dissipation factor. So put the MRAs on little balls of Mortite or BluTac for 360° radiation and airflow. A happy coincidence is that the residual inductance of Thiel/ERSE vs MRA is nearly identical, so you don’t have to compensate as you would if going from a normal sand-cast to the MRA.
This crossover circuitry is extremely subtle and carefully tuned to include all elements. So swapping one form for another is not simple. I am venturing into the mire, and learn every day how little I know of the finer subtleties of the art. Be careful.
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I also eagerly await first-hand commentary.
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All - I just picked up a pair of 3.6s from a lurker on this forum. Come winter I plan to be in full XO mode. PP> 2 2> 2.4> 3.6. Plenty of parts on hand. Slow start, other projects.
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sandy - I went through this exercise as I acquired a single sub and added another. In order to get true stereo bass information, you need 2 crossovers, since each is receiving signal from its prospective channel and outputting to its respective subwoofer. There are other ways to get summed mono bass with 1 XO which I have not investigated. Stereo bass through the SS2s is quite believable / satisfying.
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The one series is made for small spaces, moving a fraction of the air.
Woofer areas are approximately 1: 10", 2: 50", 3: 75".
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