Thiel Audio Products MCS1 manual Coherent construction, Thiel Audio, Home-TheaterSpeaker System

Product Review

Thiel Audio

CS 2.4 / MCS1 / PowerPoint / SS2 / PX05

Home-Theater Speaker System

What defines the perfect loudspeaker? Thiel Audio founder Jim Thiel would say that a loudspeaker must possess accuracy, in the broadest sense of the term. In other words, a loudspeaker should have linear frequency response, low distortion, and perfect time and phase alignment, or coherence. Although many loudspeaker designers will cite low distortion and linear response as goals, very few consider time and phase alignment critical to the overall sound. Some believe the cost of implementing such technology far exceeds the payoff, while others think the human ear is insensitive to the difference between coherent and noncoherent loudspeakers.

Thiel’s website offers scientific data to the contrary. Their Coherent Source (CS) technology is one of the hallmarks of the Kentucky- based company’s design philosophy. Thiel Audio doesn’t appear to rely on pseudoscience or unsupported claims. The company claims to be driven by research and development steeped in physics and the scientific method.

Six Thiel speakers costing a total of $14,700 arrived on my doorstep. The MCS1 ($2300) and pairs of CS2.4s ($4400/pair) and PowerPoints ($1300 each) didn’t bear much of a family resemblance (until I looked at their drivers). The SS2 subwoofer ($4900) handled the low bass, and Thiel’s PX05 passive five-channel crossover ($500) tied everything together.

December 2004

By: Anthony DiMarco anthony@hometheatersound.com

Coherent construction

Tight tolerances, flawless finishes, and hand-matched Amberwood veneers result in the elegant and sophisticated appearance of the CS2.4, MCS1, and SS2. Hyper-accurate CNC machines cut the MDF parts of each hand-assembled enclosure. The PowerPoint’s thick, alabaster-like ABS plastic shell is thermoformed, while its trapezoidal shape keeps the driver ’s baffle as close to the wall as possible.

According to Thiel, their Coherent Source technology ensures perfect time and phase alignment between a speaker’s drivers. The CS2.4 and MCS1 use a 1" aluminum tweeter coincidently mounted to a 3.5" aluminum midrange cone. Jim Thiel prefers the term coincident to coaxial because proper time alignment requires that a driver’s acoustic center outputs from the same geometric plane. While coaxial drivers share the same axis, coincident drivers share the same axis and plane. Thiel designs coincident drivers to be perfectly coherent across their frequency range. The drivers are coupled with a tuned mechanical suspension instead of a traditional crossover, which, Thiel maintains, avoids distortion.

The bass frequencies must also remain in time and in phase with the midrange and tweeter outputs. Because different frequencies travel through air at the same velocity, the arrival times of individual drivers’ waveforms will be offset if their acoustic centers are not in the same vertical plane; the result, according to Thiel, is a poorly defined image. The CS2.4’s slanted baffle guarantees that the audio waveforms from the 3.5" coincident driver and the robust 8" aluminum woofer arrive at the listener’s ears at the same time. And the CS2.4’s first-order, phase-corrected crossover ensures that the waveforms arrive simultaneously at the listening position.

The MCS1 center speaker also uses a first-order, phase-correct crossover. However, this speaker’s flat baffle relies on two shallow, 6.5", polystyrene-reinforced aluminum woofers to keep low-frequency output in the same plane, and therefore time-aligned, with the coincident driver. The shallow woofers also allow the coincident driver to be flush-mounted to the baffle, thus reducing the effects of cabinet- edge diffraction on sound dispersion.

The PowerPoint surround speaker’s coincident driver is a 1" aluminum tweeter coupled to a 6.5" woofer cone. The driver’s dispersion emerges at 90 degrees to the center of the tweeter, which, together with the 45-degree baffle, directs output away from the adjoining wall. According to Thiel, this prevents signal cancellation in the critical midrange frequencies.

Although the SS2 subwoofer’s two 10" aluminum cones and compact, room-friendly enclosure look conventional for a subwoofer, the SS2 lacks the standard phase, gain, and crossover controls. Jim Thiel’s extensive research has convinced him that room boundaries and dynamic compression due to voice-coil heating are the two main things that

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