Almost 30 years were spent in systematically searching, testing, researching and rejecting until the vision of the natural resonance-free radiation principle became an acoustic reality.
This has resulted not only in one of the most elegant appearances in the loudspeaker market, but also in a masterpiece of precision mechanics. The decisive factor in the Manger® sound transducer was the logical turning away from the more than 75 year-old transducer principle used in conventional loudspeakers, therefore doing without the piston-like movements with their faulty reciprocal overshooting.
A well-known typical 3-way speaker. Clearly to be seen the time-displaced displacements and transient errors of tweeter, mid-range and woofer. This speaker has been designed exclusively for a smooth frequency response.
Instead, Josef W. Manger relied on the principle of bending waves, which starting from the centre of a plate-like diaphragm, travel to the outside, like waves after a stone is thrown into the water. The rigidity of this thin flexible panel increases from the centre to the outside at an equal ratio, very similarly to the basilar membrane in our ear. High frequencies quickly run out in the inner area of the membrane, whereas long waves (low frequencies) concentrically reach right to the edge at the star-shaped damper. There they are absorbed so that no reflections can come from the edge.
Cross-section through the Manger sound transducer with the complex and precisely tuned functional elements. The manufacturing process demands tolerances of as close as an eight-thousandth of a millimetre (0.008 mm). Seen above the diaphragm is the stylized wave movement of the diaphragm in the range between low and high frequencies.
In this way the Manger® sound transducer controls the complete frequency range from 80 Hz to 35000 Hz on its surface and is at the same time close to the ideal of the point sound source. The conventional splitting into several ways (tweeter, mid-range and woofer) for different frequency ranges is therefore avoided. The active surface of the 19 cm diameter flexible diaphragm becomes smaller as the frequency increases so that the effective surface is always kept small in comparison to the wavelength to be radiated.
The images made with laser Doppler vibrometrics show the concentric wave movement of the bending wave diaphragm at various frequencies.
That the Manger® sound transducer in spite of its large frequency range of between 80 Hz and 35 kHz and its sensitivity of 91 dB 1W/1m can achieve the tremendously fast rise time of 13 µs is attributable to many design finesses: (see next page)