Kaiser speaker genetics connect to 1998 when Rainer Weber worked at Siemens Automotive overseeing vibration and material fatigue R&D. He'd already built speakers for personal use. His job had him hyper aware of the importance of resonance control. An introduction to Hans-Jürgen Kaiser via a student who worked on his thesis in Rainer's department led to their eventual collaboration under Kaiser Acoustics. Amongst personal hifi heroes, Rainer counts Aleksandar Radisavljevic of Raal; Steve Elford of Vertex AQ; Dietmar Bräuer of Trinity; and Per Skaaning of Audio Technology. In his lab he uses gear by Thrax, SPEC, Mastersound and Hypex nCore. In his Classic, the 7-incher covers from 60Hz to 5'500Hz to exploit wide unbroken bandwidth from the single most important driver. To compensate for its baffle step—when freqs in its lower pass band begin to wrap around the cabinet to subtract from direct sound—he fills in that power response loss with the passive radiator. The pass band of the woofer operates solely in the 4pi omni range to not impact directionality. But with his quartet of drivers and their strategic overlap, Rainer does pursue a very specific combo of monopole, di/bipole and omni radiations to give our hearing the proper mix of direct and diffusive sounds. The former help image specificity, the latter tonal warmth.


As its name might give away, the Classic was Kaiser's first model and remains their current flagship. The Vivace became a slightly downscaled version first suggested by Robert Mundorf. Hence it contains exclusively Mundorf and no Duelund xover parts and a Mundorf ATM, not Raal ribbon. The Chiara became the latest addition to their catalogue. A floorstanding Chiara to eliminate the very costly blade stand with its invisible labyrinth is under consideration. Today Rainer's day job has him work as director of Continental Automotive in charge of engine-system acoustics and R&D specific to year 2020-25 models from Mercedes Benz, BMW & VW/Audi. This laboratory position grants him rare access to specialist gear like dummy heads, laser-scan vibrometers, SPL probes, acoustic holography cameras and advanced simulation software.


When it comes to specific panel sizes and the location and thickness of internal braces, Rainer exploits Golden Ratio and Fibonacci sequences plus acoustic labyrinths which were modeled by tech contributors Vertex AQ. All of that invisible math serves to randomize remaining vibrational energies. To begin with of course, the non-homogenous structure of the 30mm Panzerholz which embeds wood fibres in resin can, like Carbon fibre, be ordered optimized for different mechanical stress behaviours, be those torsional, bending or push/pull. Unlike in homogenous materials like MDF or aluminium, the propagation speed of sound in Panzerholz varies in each direction. This unique fact undermines the build-up of resonances in the first place.


If all of this begins to suggest a rather uncompromised approach to designing and building consumer hifi products, that's very much the case. Both Rainer and Hans-Jürgen draw a secure salary from steady employment outside hifi. That's key. Even though one suspects a very unhappy accountant, they can actually afford to treat their hifi ambitions from an extremist not practical angle. You might say that Continental and the Kaiser furniture business are to Rainer and Hans-Jürgen what Spermot AG is to Soulution. If more hifi buyers knew just how many upscale hifi brands are or at least initially were subsidized by outside funding (investors, personal savings, parallel industry), they'd considered themselves very lucky indeed to have access to gear whose creation relies on enthusiast rather than hardcore business sense. Were some companies to actually charge us what they'd have to from the latter position, none of it would sell. And by the way - the Classic can be ordered in one of three different woofer sensitivities to accommodate a client's space. Should you relocate to suddenly require a different bass balance, Kaiser will replace those woofers free of charge. Finally, the word Kawero is an amalgamation of Kaiser, Weber and Rottenwoehrer as the last names of the three men involved in the original launch of this unique speaker manufacturing enterprise.


We now hand our vintage ribbon microphone to Rainer to fill in gaps in what is germane to the Classic loudspeaker on specs, design considerations and specific material implementations. "The 10" woofer is a custom version of the Audio Technology sandwich cone with carbon-fibre paper skins around a Rohacell core, with a 3" overhung voice coil for 10.5mm linear excursion and a special hybrid voice-coil former that's a combination of Kevlar and aluminium but not Per Skaaning's standard recipe. This driver features Thiele/Small parameter with extremely low mechanical losses and an oversized force factor with a low 0.22 Qts to get a shelving compensation for room gain. In other words, it's a very strong magnet to get less output in the bandwidth where room gain causes boomy bass. In house we apply a coating to the sandwich cone of a special violin lacquer called Steinmusic Maestro. That's comparable to the famous Ennemoser C37 lacquer but based on alcohol. This woofer choice matches 90 to 95% of all in-room boundary conditions. However, we also have a version with 1.5dB more output when the listening room is overdamped; and one with 1.8dB less output for overly live rooms. We recommend woofer matching with some room acoustic calculations before we start a project. Important parameters for these calculations are the RT60 of the room and bass ratios (the reverberation time below 100Hz compared to the reverberation time from 100-400Hz).


"The midrange is Audio Technology's C-Quence 18. It features a 2" underhung voice coil with 8.6mm of linear excursion and a special aluminium former. This former has special slits where it connects to the cone to control breakup of the former/cone system with a specific mechanical impedance (less stiff in the region of resonance breakup). Special T/S parameters make for a 5th-order high-pass function (ABR + 1st-order electrical). This cone too gets our violin lacquer treatment. The matching ABR uses the same cone material and curvature to get nearly the same sound as the active midrange and the same lacquer treatment. The Raal 70-20 XR uses two aluminium ribbons with oil damping between them. The matching transformer uses an amorphous C-core with Echole silver-gold-palladium wire on the primary winding and a special sensitivity tap so we don't need a resistor or gain adjustment in the crossover. Overall system efficiency is 92dB at 2.83V which needs to be measured in a hall due to the rear-firing units. The crossover slopes are a 1st-order low pass on the woofer, a 1st-order high pass—it's special to have an acoustical 5th-order high pass with ABR and cabinet—on the midrange, 1st-order low pass with additional elliptical Cauer filter at the crossover to tweeter and a 3rd-order high pass on the tweeter. The tuning frequency is 27Hz on the woofer and 63Hz on the midrange's passive radiator.

To make this shot requires being on the balcony whilst manipulating the camera through a narrow gap in the inward-opening door. This avoids shooting through the window pane. But, it relies on the widest setting of my wide-angle lens to compensate for the wide speaker distance but very close distance of the camera. This scenario creates progressive dimensional distortion towards the sides. Here it made the speakers look far deeper than they are. For reference, use the upper photo. Still, this second one gives a useful perspective to illustrate the space the speakers were playing and 'seeing'.

"The acoustic labyrinth is a very special structure where the cancellation of structure-borne sound takes place via phase randomization of the vibration. To illustrate how this works, consider material fatigue testing. This for example is performed to test whether an aircraft wing has cracks. In that instance, a structure-borne ultrasonic pulse is fed to the wing. When the reflection is perfect, you have no cracks. If you do have a lot of cracks (a lot of different transfer paths back and forth), almost no energy is returned. Our labyrinth applies the same principle with a very high number of different transfer paths and path lengths wherein vibrations cancel themselves out. The critical thing is to get the matching impedance for the vibration entering the labyrinth from a specific part; and to have just a slight deviation of mechanical impedance from one element in the labyrinth to another. Each different impedance gives you refection and transmission. It's the same as in high-frequency electrical transmissions in cables for instance. Our labyrinth is used in the 3-dimensional crossover (tankwood bracket with included labyrinth) and each component is fixed to the labyrinth individually. Some components have their own labyrinth and the wires of the cables are attached to another one to drain vibrations out of the wire.


"Another important point is that we have included some psychoacoustics in the speaker. For better soundstaging, we have implemented certain findings by Prof. Jens Blauert of the University of Bochum which are called Blauert bands.This is very important for the depth and height of the soundstage. Consider that when a sound arrives from the center, both ears receive the same signal. There is no delay between the left and the right and the amplitude is of the same intensity. How does our brain derive height and distance cues when sounds arrive from the middle? It's because our head, ears and torso affect the frequency response. We have specific filters depending on the angle of incident. This is implemented in the frequency response of the Kawero Classic. The important thing is determining whether you implement this in the first wave front or in the diffuse field. Here I simply don't wish to disclose any further expert knowledge. As to recommended setup, the distance between the main cabinet's front edge and the tweeter housing when placed straight out should be exactly 24mm for time alignment. Toeing the main cabinet in will give more focus but less soundstage depth. Toeing out does the opposite. Due to the down-firing port, the air between the bottom plate of the cabinet and floor acts as an extension of the port. If your feet are about the same length as the Stillpoints, the original tuning remains. If the gap shrinks, the bass will extend lower but with less punch; if the gap increases, the opposite happens." Due to the small contact patches of the Stillpoint risers and the massive weight of the speakers bearing down on just three areas, I worried about damage to the softer wooden floor of our rental. Hence I replaced them with the far larger Artesania Audio Exoteryc footers from Spain. Those spread the same weight over more than ten times the contact area. And, using the hard Nylon not Neoprene captive floor discs beneath them, I could slide the speakers back and forth and easily change their toe-in. As fellow renters can appreciate, any damage to our dwelling would eat into our very sizeable security deposit. Little is as expensive as replacing sections of old parquet flooring. Hence certain things aren't negotiable, audiophilia be damned. Whilst my solution did lower the speakers, hence their F3, I noticed no ill effects on bass textures. But, this performance aspect is tunable by adjusting gap height. Relative to the Goldmund amps, "Bob Visintainer of Rhapsody Music & CInema has exactly the same combination of Telos 360 + Kawero in his NY showroom. He will use this combo at the Axpona show in Chigago so your US-based readers might experience this system there."