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The separate black baffle isn't just for appearance but supports the desired HF radiation pattern by way of vertical beaming to reduce floor and ceiling reflections. Being viscoelastically decoupled, this baffle also cuts down box resonance migration toward the listener. Pleasant surprises don't stop with the box whose build quality and layout are 1a but include the driver. Here I'm not referring to the woofers in triplicate about which the maker talks ideal low mass/stiffness ratio for their paper/aluminium sandwich membrane, generous +/-8mm excursion and oversized motor. No, the apple of the eye is the mid/high unit.

Not only is it a coax—rarer in this price class than two discrete drivers—but one with a flat membrane for the lower frequencies. That's gets even more exclusive. Think Elac, Thiel Audio, perhaps Piega though the Swiss deal in ribbons... perhaps Vienna Acoustics and now Teufel. That's quality company. And Teufel certainly isn't shy blowing the horn of the usual coaxial advantages like point-source dispersion here between 350Hz and 22kHz and path-length equality for superior time-domain behavior. But why a flat membrane? Don't those sacrifice stability compared to the ubiquitous cone? True if you use the same material explains Jörg Weber.


"A nawi membrane (a certain hyperbolic funnel geometry) indeed enjoys structural stability advantages over a comparable flat membrane. Yet with a dual-concentric geometry that's not an isolated factor. Mechanically there are strengths which require little material investment to arrive at low moving mass. The form factor on the other hand creates a waveguide which affects the tweeter's radiation resistance. Such an acoustic horn function creates its own set of challenges which could sacrifice some mechanical stability.

"Here a flat membrane circumvents the compromise between mechanical and acoustical behavior by being acoustically mostly neutral to avoid premature treble beaming whilst also improving the off-axis response in the midrange's presence region. These important advantages are paid for with greater developmental costs and higher moving mass. And that's precisely the challenge: how to develop a material which minimizes this added weight."

Teufel's solution is an aluminum/kevlar sandwich with internal honey-comb structure for 12mm total thickness. This donut membrane is so stiff as to not require an inner termination where the tweeter sits. Here the midrange moves freely, hence the 10cm voice coil had to go elsewhere, i.e. outside. A side effect is the lack of central spider. Instead there's a second surround mirror-imaged to the outer one to stabilize the flat midband membrane. Clearly this driver marches to its own drummer. Related advantages of its unusual build include lack of thermal compression due to sheer voice-coil diameter; and minimized acoustic compression, resonance and reflections from the open construction's lack of spider. Finally Jörg Weber points at the symmetrical double-surround suspension which cancels out mechanical nonlinearities. Given such an extensive list of virtues, the >3.500Hz 1" soft dome tweeter would seem sorely conventional by contrast. Teufel likely disagrees but no matter. With an R&D cycle of 2½ years for this patent-protected coaxial driver, one suspects that it'll appear in other Teufel models soon.