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This review first appeared in the April 2009 issue of hifi & stereo magazine fairaudio.de. You can also read this review of the Thiel Audio SCS4 in its original German version. We translated it through a syndication arrangement with our German colleagues. As is customary for our own reviews, the writer's signature at review's end shows an e-mail address should you have questions or wish to send feedback. All images contained in this review are the property of fairaudio.de or Thiel. - Ed.

Reviewer: Jörg Dames
Sources: Fonel Simplicité (with variable outputs for direct drive), Audiomeca Obsession II, Wadia Wadia 170i Transport & Apple iPod & Benchmark DAC1 USB
Amplification: pre/power - Funk LAP-2.V2/Myyrad MXA 2150; integrated - Fonel Emotion, Abacus Ampino Rieder, Lua 4040C
Loudspeakers: Thiel CS 2.4, Sehring S 703 SE, Quadral Rondo
Cables: low-level - Straight Wire Virtuoso; high-level - HMS Fortissimo, Reson LSC 350
Review component retail: €2.200/pr

"If you understand loudspeaker design theory, you haven't understood a thing." Misappropriating the famous Quantum Physics comment by Danish physicist and Nobel Prize winner Niels Bohr is a bit far-fetched but particularly speaker theory does seem to be a sector that makes clear just how little is really clear. This could pertain to basics such as optimal number of drivers but extends to a bundle of conceptual beliefs about the 'right' form of power transfer (dynamic, electro- or magnetostatic), appropriate membrane material (prone-to-ringing metal or lossier paper) and ideal crossover (shallow phase-correct or steep for narrower operating zones) for just a few.

One might call it a matter of personal taste and application rather than hard science. Still, as soon as these subjects come up, rather uncompromising arguments follow. It hasn't been long since I had designer Herr Günter Nubert on the phone who fancies 6dB filters about as much as an inner ear infection. Thiel loudspeaker developer Jim Thiel from Kentucky is at least as established but equally firm on the inverse company motto by insisting on 1st-order networks exclusively. Consequently, this applies also to their SCS4 model under review.

Tech
This signature trait is accompanied by solid technical and -- as we shall see -- aural backgrounds. Unlike steeper filters of the 2nd, 3rd and 4th order kind (12dB, 18dB, 24dB), 6dB/octave filters operate with improved phase linearity. Liabilities include broader operating bandwidths and greater overlap for and between drivers to create greater burdens and negative interferences. Important to mention in this context is that figures like x-dB of filter degree and terms like phase coherence sound definitive but aren't. Electrical attenuation isn't synonymous with acoustical attenuation. Declarations of the former often fail to specify how electrical networks and their drivers' acoustical behaviors sum at the ear.

In short, 6dB acoustic and 6dB electrical need not be the same. That fact is at the heart of Thiel. The Americans insist that true phase coherence for real time fidelity (whose advantages, it must be added, also are subject to endless debate) is possible only with 6dB acoustical filters. While numerous paths may lead to Rome, it's a fact that in matters of impulse and step response, Thiel speakers routinely furnish brilliant measured results. To more closely approach their championed ideal of a time-correct point source (which involves physical baffle offsets with multiple drivers), Thiel employs another signature solution, the coaxial transducer. While the bigger models add woofers, the SCS4 two-way uses just one coax. Its 25mm tweeter is related to the one in the €13.800 flagship CS 3.7 and combines an Aluminum-Magnesium diaphragm with natural latex surround. Due to shallow attenuation and broad coverage, this driver has to stretch itself on demand. On the spec sheet, it counters with 1.5mm excursion which is significant for a tweeter.

The turnover frequency hovers at 2.5kHz below which a 16cm Alu-Magnesium cone with a resonance-damping Polystrol foam layer takes over. This sandwich construction weighs in at 5gr (9gr with voice coil). The bonded layer construction allows for a relatively shallow physical flare to minimize horn loading of the tweeter. Unlike the dual-concentric driver in my Thiel CS2.4, the SCS4 version employs two discrete under-hung voice coils (relative to the magnet's gap height, those are very short to never leave the fixed flux field regardless of excursion to improve linearity). Apparent from the outside meanwhile are two bass reflex ports and the Alu/Magnesium bonded 25mm baffle which stiffens the enclosure. For the former, Thiel states a greater compound diameter for reduced port noise and less midrange contributions than a single bigger port tube would cause.

Sound
It was about 21:00 hours, i.e. time to relax. The SCS 4 was preconditioning in the room next to my listening space. Maria was out and no other commitment on the calendar. I reached for a bottle of Salice Salentino and some chill-out listening. The system consisted of my ca. €6.000 Thiel CS2.4 driven by Fonel's Emotion integrated (about €4.500) fronted by the matching Simplicité player (€2.850). Spinning was the very varied 1998 Psyence Fiction Trip-Hop album by U.N.K.L.E with its numerous guest stars. A few gasps and gulps later, fingers itched and the prospect of comparing two stable mates became irresistible. I quickly walked the minis plus stands out of the neighboring room, swapped cables and keyed onto interesting differences very quickly.