The inside story

THIEL Audio is named after the company's co-founder and chief product developer, Jim Thiel. Jim visited Crutchfield to lend a hand with the training sessions for our Sales and Tech Advisors, and he offered a mini-seminar on loudspeaker design. Although THIEL speakers are classified as "box" speakers, Jim's out-of-the-box thinking is the key to their exceptional performance.

The THIEL approach to speaker design and construction focuses considerable effort and expense on increasing each component's strength and stiffness while reducing its susceptibility to vibrations. That applies to the cabinet, drivers — everything.

Seen from above, the CS3.7's front baffle is sloped to provide time coherence between the woofer and the mid/tweeter array.

Rounded cabinet contours, an aluminum cap piece, and a machined-aluminum front baffle are among the design features that set the CS3.7 apart from previous THIEL speakers. The super-rigid cabinet sides are formed from 15 layers of hardwood laminated together into a curved shape under high pressure. The sloping front baffle provides time coherence between the woofer and the mid/tweeter array, which preserves music's timing information, ensuring that all of the music's spatial cues are reproduced naturally.

Two custom-designed "wave-shaped" 10" aluminum drivers occupy the bottom half of the speaker. The upper unit is a woofer while the lower one is a bass-enhancing passive radiator. The passive radiator's job is similar to that of the port in a conventional bass-reflex speaker — it allows low-frequency energy inside the cabinet to pass to the outside, but in a very controlled manner.

The mid/tweeter array consists of a 1" aluminum dome tweeter coaxially mounted with a 4-1/2" wave-shaped aluminum midrange.

The newly designed 4-1/2" aluminum midrange driver has ridges radiating from the center to the outer edge. The ridges increase strength and stiffness, extending the driver's operating range out to an astonishing 20 kHz. The midrange is actually crossed over to the tweeter at only 3 kHz, which means the driver has plenty of headroom for maximum accuracy. According to Jim Thiel, the midrange's extended response is a key factor in the CS3.7's exceptional midrange purity and delicacy.

THIEL's complex crossovers are the gradual-transition "first-order" type which provide complete accuracy of signal amplitude, phase, time, and energy.

The CS3.7s use an elaborate crossover network employing "first-order" filters. This type has a more gradual roll-off compared to other filter designs, and it requires higher-quality drivers that can cleanly and accurately reproduce an extended frequency range. First-order filters have less of a tendency to distort the musical waveform and are especially prized for their phase accuracy, which can result in better imaging than speakers employing crossovers with steeper slopes. (I've owned speakers with first-order filters for nearly 20 years, and can attest to their imaging and soundstaging prowess.)

While many high-end speakers provide dual sets of terminals for "bi-amping" or "bi-wiring," THIEL speakers do not. Jim Thiel's sophisticated crossover networks do much more than act as "traffic cops" directing the right frequencies to the right drivers. They help to optimize energy response and tonal neutrality, and Jim doesn't want any outside crossover or unnecessary cabling compromising his work.