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Handcrafted loudspeakers & monitors
for audiophile professionals and connoisseurs


The cabinet – a symphony in wood

The cabinet is the foundation of every loudspeaker and the basis for high quality sound re-production. It "only" needs to meet the following criteria: extreme rigidity, no natural resonance, efficient soundproofing, the right dimensions (volume) and the right weight (mass)

To assure the first two points we had to violate our own principal of hand crafting: we have to use 3D CNC milling. All cabinets and every wooden component are CNC manufactured with a tolerance of 1/10mm – you simply cannot archive such accuracy by hand. The multiple chambers concept of our cabinets in conjunction with the complicated matrix bracing in nesting architecture reduce cabinet resonances to a minimum. So we prevent tone colouring – basically we are doing exactly the opposite compared to building a sounding instrument like a violin. All components are glued together using a special 2-component glue. The result is a "silent" loudspeaker cabinet which impresses as much from the inside as from the outside:

surrounTec™ LautsprechergehäsesurrounTec™ Gehäse matrixverstrebt

The dimensions of our speakers results from the specifications from our Accuton pure ceramic drivers – our demand is that every driver gets the right back pressure and the correct uncompressed air volume so that it can work most effectively. The challenge is to assure an identical air pressure before and behind the driver. The result is that the driver can play freely, like if it was in a vacuum.

Also very important is the ventilation of the speaker cabinet. Because of its easiness most speaker manufacturers use front ventilation of their speakers, despite the fact that the opening acts like an extra driver! In contrast every surrounTec™ subwoofer ventilates to the back and our monitors to the sides. Since no tone is generated by our reflex ports you only have to consider not placing the speakers too close to a wall so that effluent air does not hit a wall directly.


The acoustic baffle called Isoplate

We do not mount the drivers directly into the cabinet. Instead we use a up-to 130mm think acoustic baffle which complies with multiple functions: on the one hand the drivers move forward and backward. This movement energy is transferred inverted into the acoustic baffle and adjacent into the cabinet. This yields mechanical vibrations which cause distortion to the radiated sound signal. To prevent this the surrounTec™ Isoplate is made of multiple viscoelastic connected material layers which absorb a great deal of the micro movements of the drivers.

surrounTec™ IsoplatesurrounTec™ Schallwand

There is even more to it! All our professional products feature another step of mechanical isolation: the Reis-Ring (named after its inventor). This is the element which connects the driver to the sound baffle. It is designed to also absorb micro movements. So the driver hast two or four (in our high-end products) steps of mechanical decoupling from the cabinet itself.


The mechanical time-alignment of all acoustic centers

Last but not least: the acoustical centers of all installed drivers have to be placed on one line (or ideally on an circular arc). This is known as Time-Alignment. The reason behind the Time-Alignment is that a conventional loudspeaker without this feature is bound to work faulty. Please consider the following example:

Original signal & responses of the drivers (the time offset is a result from the unaligned acoustical centers):
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surrounTec Time-Alignment surrounTec™ Time-Alignment

The original wave-length signal is radiated from the tweeter prior to the mid-range driver - so in addition one gets an altered sound signal. Typical measuring methods to display the frequency response, like the FFT measurement, do not show the implications of the wrongly added signal because the FFT measurement does not take the transient effect of the drivers into account. Thus only the swung-in condition (see area marked "Phasengleichheit" pictured above) is analyzed. The wrong summation of the individual amplitudes does not stand out since the measurement signal of the frequency response measurement has a constant phase..

Consequences of the wrong summation:
Let´s examine the point with the largest amplitude of our original signal: it is being averaged in the acoustic response of the drivers. So the acoustic sum from tweeter and mid-range driver can never reach the amplitude from the original signal. The subjective evaluation yields disguised fine gross dynamics. So one can say that in order to transmit the audio signal correctly, the accurate summation of the amplitude of each driver and their timing is essential to sustain the amplitudes of the original signal.





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