Thiel Owners

audiojan - Thanks for the update. I have become aware of the audibility of the midrange hash introduced by a port / passive radiator having effects on the whole presentation. I recently participated in a product development blind A/B test where everyone heard that hash in dramatic fashion. (Tannoy - ported)

There is a hypothetical possibility to take your improvements even further.   See Atkinson's CS2.4 review. Note the -10-20db junk from 100 to 1kHz.  Similarly the reflex tuning introduces high-pass phase shift on the woofer roll out. My wish list includes immobilizing the radiator for sealed box second order bass rolloff (like the 3.5) and augmenting with second order SS x Integrator bass. The potential improvements intrigue me greatly.

Of course such modifications would apply to other models as well.

In that light, I hope to find a Thiel Integrator: Any physical condition, $1K max. 

unsounds post  from 09-18-2018 re the doubling down into 2 ohm requirement has me wondering -- can we once and for all clear this up: is it absolutely necessary to have that capacity in order to drive Thiels (I'm thinking of my 3.7s) to perfection? I mean, very few amps advertise this ability. What about the Classe CA-M600 (600 8 ohms/1200 4 ohms)? Not rated into 2 ohms, but certainly enough current, no?
Todd

Todd - I am a strong proponent of the 2 ohm deal, since Thiels drop near 2 ohms over broad frequency ranges. I make a big deal out of the requirement because many current sources exhibit considerable anomalies as they run out of oomph. That distress shows up in many sonic results. And those results are blamed on the speaker as sounding x, y, z.

Amp circuits are quite individual, so the 2 ohm double may not always apply. And, as you say, something as big as that Classé is not likely to run out of power in any normal situation. Other amps in the family produce 3x the 8 ohm rating into 2 ohms. That topology is both stable and plenty strong.

My intent has been to advise against amps that are not stable driving 2 ohms. For instance the PS Audio BHK-250 stereo amp is rated as "stable into 2 ohm load", but in fact can only drive that load for short durations. It is not suitable to drive your 3.7s and PS will tell you that if you ask the right questions. Which is my point. Get an amp that will drive a 2 ohm load continuously.

Tom - Thanks for the response. Just to clarify: by "other amps in the family,"  are you referring to the Classe family?
Finally, can we get a list going of amps that satisfy the continuous 2 ohm criterion? Certainly the big Krells, the Classe Omega ... but, what else?  And, what does one look for besides a 2 ohm provision in the published specs? Are there other ways of discovering that an amp without the 2 ohm spec will work?
Todd

I would love to see such a list of 'best Thiel amps'. But I am not current on the market offerings beyond the usual suspects listed in this forum. I know that "best sound ever" at the 3.7 introduction was the new biggest and best Bryston.

Yes, I meant Classe in general. When I was paying attention, they had one circuit topology executed at different power levels and passive component qualities. They were (and probably still are) a high current design. Dave Nauber, president of Classe, is a long-time Thiel associate and could speak knowledgeably about how their amps drive Thiel.

As to what to look for, the 2-ohm current requirement behavior is the major Thiel problem. After you limit the field to those amps that can, the rest becomes personal taste and opinion. As a personal story, I fell in love with Tim de Paravicini's Esoteric Audio Research amps in the mid 80s on the CS3.5. We set it up at CES to considerable delight of the pre-show manufacturers walk-around. However, some badass bass showed that it couldn't control the back emf of the equalized woofer. We abandoned it and most other tube designs. The point is that I would look at EAR's tube or solid state amps because they have such gorgeous delicacy, and ask the hard questions about driving near 2-ohm loads - show EAR the load curve.  I would also look at PS BHK-300 for similar reasons. In fact, I'll be auditioning a pair of those later in the fall. My must have factor is a current source designed for that load. The rest is preference.