Thiel Owners

tomthiel

This is fascinating. A history lesson, a reflection on the consequences of decision-making, and a deep repository of product information all in one.

That necessitated electronic bucket-brigade delay on the upper and lower midrange drivers accounting for nearly half the component count in that huge crossover. Those coils and caps are all in the signal-feed path, which creates most of the sonic reticence experienced in the CS5.

My immediate thought reading this - and please forgive me if it sounds in any way sacrilegious as this is certainly not my intent - would be to yank out the passive crossover, amplify each of the five channels individually, and control the amplifiers via a 10-way active crossover, DSP-enabled speaker management unit, which in addition to crossover duties would allow for precise delay adjustment for each driver / driver pair, and room correction of course.

Was anything like this ever envisioned?

devinplombier - we did explore low level crossovers. Net result is that we knew our niche which was all analogue and purist. Other folks have done versions of what you suggest. We always looked at overall cost effectiveness and separate amps, cables, etc. are not cost effective solutions, in our opinion. Also, the time of the CS5 development was 1988 - early and crude digital performance.

Of additional interest may be that the level of control needed for net resultant 6dB/octave slopes over approximately 7 octaves is far from trivial, even with digital modeling. We committed to minimum phase x time aligned performance with the 1978 model 03 and never looked back. Note that one would need to model, in addition to the driver roll-off slopes, the various reactive circuits to cancel resonances as well as the impedance correction shunts to maintain Thiel's resistive (non-reactive) load profiles. Most folks are very surprised how difficult that is with off-the shelf digital filters.

The approach we were intrigued by is low-level, active analog circuits before the power amps. In fact one of our first, pre model 01, trial products in 1975 was just such a speaker with 3 built to order amps and custom active crossovers in a 10" 3-way in a large bookshelf format. That product was unfeasible for a new company in a farmhouse. The technical aspects were manageable and indeed prototypes were impressive. But we lacked the stuff for market education and penetration. Indeed, powered speakers never became very popular.

To your question: we envisioned a lot. Line sources, spherical globes, di and bi poles. Active equalization was our first market entry and contained enough uniqueness to create more demand than we could meet for the next 30+ years.

Cheers, TT

Very interesting information, everyone! Given the fact that my listening triangle is about 8ft, I am thinking that the 2.4 might work better in my room.

Other than deeper bass, what would people consider to be the other sonic advantages of the 5i over the 2.4? 

lars - a few thoughts. I have rather recent acquisitions of both CS5i and CS2.4, but not much actual experience with either of them. I’ll jump to my conclusion first which is that the 2.4 might well suit your needs better due to what may be your fairly small space.

The CS5 has individual drivers, which at 8’ don’t integrate their soundfields very well. Also, the primary advantage of larger speakers is to fill larger spaces with deeper bass and higher amplitude. The 5 will do that only if you have the proper amplification to drive them, which as you’ve read here is a very big deal. The 2.4’s upper coax tolerates listening at any distance without compromise. The listener is freed from the triangulation necessary for individual drivers to integrate.

Another trajectory is that as Thiel and in particular Jim learned more he developed more sophisticated drivers. The CS5’s only driver from the ground up is the UltraTweeter. The ’i’ designates ’improved’ and adds copper motor shunts to the 3 woofers for significant bass improvement. The Focal lower and MB/quart upper midranges are very good stock drivers having none of Jim’s innovations. I’m saying that the 5 is earlier on Jim’s journey and as such the drivers are more ordinary. But, if you are filling a large space at full amplitude, the 5 puts out much more sound. Unless, of course, you can’t handle the power in your room.

There is another aspect that matters a lot to some people, myself included. The CS5 has true sealed bass. The transition from midrange to bass (down to 10Hz) is true first-order phase and time coherent bass. It acts like a real acoustic instrument in your space. The 2.4 is a very well executed reflex bass system using a passive radiator. The transition from the upper bass (woofer) to the lower bass (passive) at 24dB/octave (4th order) introduces a full cycle of delay in the sub bass - more than 20 feet behind the upper bass. That alignment has become acceptable in nearly all speakers, even costing $6 figures. But it is less authentic than first order sealed bass.

My studies in audio neurology suggest that the brain builds audio understanding from the bottom up. And therefore inserting the timing discontinuity between deep and mid bass consumes effort to decode and suspend judgement regarding the error. Again, the 2.4 bass is about as good as reflex bass gets, but it’s still reflex bass.

The 2.4 is easier to drive than the 5. Reflex bass eliminates current draw in the deep bass because the bottom octave is supplied via tuned mechanical delayed resonance, not a driver motor.

A pair of 2.4s might be found at under $1K. And a stellar and affordable upgrade path exists because there is no electronic crossover between the midrange and tweeter. The 5, on the other hand has 4 electronic crossovers, each far more complex than any of the 2.4 circuits because the later 2.4 drivers behave better, needing less correction than those in the 5 / 5i.

Tom T

New Year's Eve - All