What defines the perfect loudspeaker? Thiel Audio founder Jim T h i e l
would say that a loudspeaker must possess
a c c u r a c y
, 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
c o h e r e n c e
. 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.
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
c o i n c i d e n t
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
a n d
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
c r o s s o v e r. 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
December 2004
Product Review
Thiel A u d i o
CS 2.4 / MCS1 / PowerPoint / SS2 / PX05
Home-Theater Speaker System
By: Anthony DiMarco
© Schneider Publishing Inc.
w w w . h o m e t h e a t e r s o u n d . c o m
