Thiel CS7.2 loudspeaker
By Brian Damkroger   •   February, 2000 When I describe the Thiel CS7.2 to friends, the word that gets the biggest reaction is "simple." Veteran audiophiles protest, noting the big Thiel's multiple drivers, complex cabinet, and elaborate, zillion-element crossover. Nonaudiophiles just glance at the 5'-tall speaker, smile sympathetically at Bonnie, and roll their eyes.

But in the world of ultra-high-end loudspeakers, the CS7.2 is actually quite simple. The other super systems I've used—big Infinitys, Genesis 200s, Audio Artistry Dvoraks, and the like—have been bi- or even tri-amped. There are four towers, external crossovers, and a brigade of amplifiers to deal with, and cables everywhere. With the CS7.2 there are only two speakers, one stereo amplifier, and one set each of interconnects and speaker cables.

But when I say "simple," what I really mean is the engineering. Though its execution may have ended up being complex, the CS7.2's design principles are elegantly simple. Jim Thiel begins with the premise that, to communicate musically, it's necessary to achieve fidelity in four areas: tone, spatial resolution, transient reproduction, and dynamics. This gives rise to a number of technical requirements, which in turn lead to a set of design goals. It is against these goals—uniform frequency response, accurate time and phase response, low energy storage, and low distortion—that all decisions and tradeoffs are judged.

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In that light, everything about the CS7.2 makes perfect sense. Multiple drivers are the simplest way to ensure uniform frequency response and radiation. The sloping baffle time-aligns the voice coils, and the first-order crossovers give you phase coherence. The rigid, 1"-thick cabinet, complex inner bracing, 4"-thick cast mineral baffle, and custom-built aluminum drivers all reduce energy storage and distortion—as do Thiel's short-coil/long-gap motor assemblies, which ensure that the voice-coil operates entirely within a linear, consistent magnetic field.

Each of these design elements is a direct outgrowth of Thiel's original premise, technical requirements, and design goals. Each does, however, pose its own set of engineering challenges. The idea of a rigid cabinet is simple, but Thiel's bracing scheme and baffle are not. The same is true for low-distortion drivers: simple concept, difficult execution. Because of the considerable overlap between drivers, first-order crossovers must be complex to incorporate all of the factors necessary to achieve a seamless blend. The coaxial midrange/ tweeter poses its own challenges, overcome here by a complex, three-layer sandwich construction and a carefully engineered cone shape.

Sure, if you just look at the details, the CS7.2 is complex. However, if you follow the process—start with the desired performance attributes and move forward into the CS7.2's design and implementation—it becomes obvious that each element is only as complex as it needs to be to do the job.