Thiel Owners

Happy Friday! All

@beetlemania, @jafant,

https://www.manualslib.com/manual/170241/Thiel-Cs2-4.html?page=5#manual

The CS 2.4's are spec'd at :

87 dB@2.87 V -1m

and suggests a minimum of 100 Watts per channel


I would offer that even accounting for gain from room lift and the doubling of speakers, the sensitivity drop off from standard 8 ohm rating to actual load by 3dB for each halving of impedance and similar loss to actual recommended listening distance of 3 meters would preclude a 90 dB sensitivity with CS 2.4's . 
 With an admittedly crude phone app I reach peaks in excess of 100 dB's at my listening position, sometimes up to a few times per day, though only averaging dB's in the mid 60's. Many amplifier manufacturers suggest that amplifiers are in their most linear state somewhere between 10 and 20 % of rated full power, and further recommend that one have 8 to 10 or more times that of clean head room power available beyond that.
 As far as the ability to "vomit" power into 2 Ohms; I would suggest that ability to do so is suggestive of a healthy response for the speaker load at hand. Not being able to do so is often suggestive of a weak power supply and/or poor heat dissipation capabilities. If an amp manufacturer's amp is capable of doubling down into 2 Ohms or come reasonably close to doing so, they are likely to brag about it. If an amp manufacturer fails to list their amps specs into 2 Ohms, it's likely because they are not proud of those measurements.
https://www.stereophile.com/content/ayre-acoustics-ax-5-integrated-amplifier-measurements
  When Stereophile measured of the AX-5 into 2 Ohms it clipped at 220 Watts with only one channel driven with a higher level of distortion at lower powers. …"That the AX-5 was not as comfortable driving 2 ohms as it was higher impedances can be seen if fig.6.".."But into 2 Ohms (green), not only is the THD higher, but the level was a little unstable at the lower frequencies."
https://www.stereophile.com/content/thiel-cs24-loudspeaker-measurements
 With the 2.4's measured sub 3 Ohm load and difficult phase angle, that might be good enough, but I think one could do better.
 When driving Thiel's, it might be prudent to ask; what would Jim Thiel do?

Unsound - I can shed some historical light on your query of "what would Jim Thiel do?" Jim's thinking was decidedly compartmentalized. He considered his business that of designing loudspeakers and the other elements to get right were the business of other entities - designers, technologies, etc.

We started with the Phase Linear 400 and then Nelson Pass' Threshold, then Classé, and gradually developed trade relationships whereby we swapped speakers for the best of form from Audio Research, Conrad Johnson, Mark Levinson, and Krell. (There were undoubtedly others after I left in the mid 90s.) I know that the xx.7 series were developed primarily with Krell's 600fpb.

I remember vividly a visit from Larry Archibald (then incoming publisher of Stereophile magazine) where we demonstrated, among other models, our new CS1.2, with underhung, shunted motor, aluminum tweeter and other advanced-for-the-time technologies. All were quite impressed. The speakers sold for (approximately) $1500 / pair and the amps driving them were (prox) $15K. Larry argued the "marketplace absurdity" of such a pairing. Jim argued that good amplification was his assumption for his designs.
I would classify Jim as unassailable or incorrigible in the realm of his assessments, his assumptions and beliefs regarding such matters. And that was problematic within the company. Company politics demanded that Jim was always right, so all products were developed with relatively "great" amplification. (An inexpensive product might be developed with a $10K amp and an expensive on with a $20K amp, etc.) The same thinking applied to cables. And as you might know, our listening room was purpose built at 14' high x 22.5 wide x 35' long with low-key but very effective acoustic treatment. So, let's say that the working environment of our speakers under development and test was somewhere between great and rarely reproducible in our customers' real-life situations.

Both Larry Archibald and Harry Pearson in his original 03 review took Jim to task for his compartmentalized position, as have numerous later critics either directly or indirectly. Most of you as fans have carefully and painstakingly worked around these interface problems. Congratulations to you. Jim would be pleased for you and proud of your ingenuity. But it wouldn't have altered his position of "that's not my job". 
Note that there were other amps after my time. Dave Gordon, Thiel's national sales manager from the late 80s to late 90s would know them all, both at Thiel and in the field.

In my present work I am considering real life application environments. My amps and cables and room are quite modest and quite likely bettered by many of your environments. Among the lessons I have heeded is that there are problems attributable to the speakers which can be ameliorated in the speakers rather than shifting responsibility to source or chain. There is always more to learn, and I am immensely enjoying this learning experience.

@unsound

Um, one of us has the actual *experience* of listening to the CS2.4 driven by an Ayre AX-5.

Stereophile’s measurements help us to discern that the AX-5 is not a good match for the CS5 or Magnepan 20 and shouldn’t be mated with the CS2.4 *if* the listener demands 100 dB peaks. You might note that the CS2.4 never drops to 2 ohms (it was measured by 3 reviewers, Stereophile seems to have measured the lowest value). As for

But into 2 Ohms (green), not only is the THD higher, but the level was a *little* unstable at the lower frequencies

Not only does the CS2.4 never drop to 2 ohms but the AX-5 behavior JA is describing was observed only in the bass where the CS2.4 impedance curve greatly rises. Also, those were steady state test signals, not music!

Regardless, those measurements tell you *nothing* about how the amp sounds. You need ears for that part!

From the Thiel owner’s manual for my product:

Keep in mind that sound quality is usually much more important than sound quantity. There can be large differences in the sonic performance of two amplifiers of equal power, and this is more important than large differences in power. Most everyone will be happier with a 100 watt amplifier of high sonic quality than a 200 watt amplifier of mediocre sonic quality. For this reason, we feel there is no substitute for listening in making your amplifier decision.

Apparently, I’m in the "most everyone" camp. Good day, sir.

prof,

Thanks for the 2.7 vs Joseph comparison.
Although monaural, the SS2.2 sub reinforces the lower bass on my 2.7s.