Floor-standing Speakers

Thiel MCS1 LCR Speakers

ARTICLE INDEX

Design

The MCS1 is a flexible speaker designed to be used horizontally as a traditional center and vertical for either main, surround or even as a vertical center in an LCR configuration. The heart of this speaker is then ingenious custom designed and built co-axially mounted tweeter-midrange driver. Unlike other co-axial designs this is not just a tweeter mounted on top of a midrange, rather they share the same voice coil, removing the need for an electrical crossover, as the drivers own structure acts as a mechanical crossover, preventing certain frequencies from arriving at the tweeters dome. By coaxially mounting the drivers you achieve almost perfect time coherence as the drivers are essentially origination from the same location.

Thiel MCS1 Loudspeakers

Bass comes from two custom made dual 6.5" midwoofers, crossed over using an advanced first-order (6dB) network. This reduces phase issues as the signal manipulation is kept to a minimum. This type of network is not easy to use, requires careful driver selection and is considered by some designers as the perfect crossover network. Thiel has been perfecting this type of crossover network for over 30 years.

What is interesting about these mid-woofers are their motor structure. This is the part that pushes/pulls the cone converting electrical energy into mechanical energy. Most conventional drivers use a long voice coil and a short gap. Thiel does it the opposite, using a short voice coil and a long gap. The voice coil drives the cone when the magnetic forces in the gap act upon it. When you have a short gap and long voice-coil part of the voice coil will always be outside of the gap and therefore uncontrolled. With the system Thiel uses the entire voice coil is within the gap. Thiel then adds a copper ring and sleeve system which keeps the magnetic field constant even under high power. Thiel claims this reduces distortion by 90% over conventional drivers. They have been working with this motor structure for over 25 years and since 1997 have used it in every driver. It is nice to see such commitment to design and engineering philosophy's.

For deep bass augmentation Thiel was kind enough to send along one of their SS2 Smart Subs. This overbuilt, yet visually unobtrusive sub box contains 2 ten inch drivers, a 1000watt class d (switching) amplifier, and some unusual electronics. First thing you will notice is the omission of the most commonly found (and most commonly misused) control, the cross-over adjustment.

The reason we need cross-over adjustment is to blend the sub with the main speakers, and prevent unnecessary frequencies from arriving at the subwoofer. Thiel offers a passive cross-over network custom made to match the Thiel speakers your pairing the sub with. This differs from conventional design as the PXO5 crossover does not remove any signal from the main speakers. In this setup it is used to augment the mains, rather than off-load the bass demands.

The only controls available to the user are LFE level control, which only regulates the level of output when using the LFE input (does not have any effect when using the main inputs) as well as side-wall and rear-wall distance settings. Those last two are what makes this sub smarter than your average woofer. When you adjust those you are telling the sub how close it is to a wall, this in turn adjusts the frequency response to reduce room-related frequency anomalies. Many subwoofers today offer room-correction which adjusts for a flat frequency response at the listening position using a measurement microphone and a digital signal processor. One weakness with auto room response is the microphone and sample positions. Slight changes in microphone positions can influence the response causing invalid correction, or correcting only for one seating location which may cause another seat to sound worse. Thiel removes those possibilities by compensating for boundary locations. This is truly a unique option, one I have yet to see in any other product.