Horn loudspeakers are the oldest and most natural physical principle for rendering sound. Their functionality until today has undeniable advantages over other loudspeaker technologies. In this section we invite you to follow us through history and present time, theory and application of this fascinating technology!
As distortions stay at negligible levels, compressed dynamics simply do not occur.
To avoid typical distortions of horn drivers, our designs omit the usually applied compression chambers in the midrange section.
By applying horns, membrane excursions are easily reduced by a factor of 10-50, for the same SPL output!
The curvature of our horns is calculated with ultimate mathematical precision.
The horn principle is as old as the universe, maybe even older. Everybody knows the horn! In nature the principle of the horn technology is ubiquitous. Our mouth is a funnel, as are our ears. And we form our hands in the shape of a cuped funnel to amplify our voices and to improve the intelligibility when listening. Even the architectural design of the ancient amphitheater in Epidaurus is based on the acoustical principles of the horn.
A horn funnel effectively guides the motion of sound waves and thus substantially increases the sensitivity and effectiveness of sound radiations. A horn is the most natural and powerful way to amplify sound.
It happened more than 100 years ago, when, for the first time, Emil Berliner presented his gramophone to the public. The horn of the gramophone amplified the mechanical oscillations of a pin running along a groove in a disc producing a sound that could be heard by the human ear.
This technological feat was followed by the search for the optimal shape of the horn. This revealed to be a bold and complex venture as already hinted at by Harry F. Olson: “The design of a horn loudspeaker is usually a long and tedious task”. Similarly, horn pioneers as Gustavus, Webster, Klipsch and Voigt required decades in order to explore the laws of the horn technology. In 1926 Paul Voigt submitted his first tractrix horn to the British Patent Office.
The hey-day of the horn loudspeaker followed. At that time tube amplifiers had only very low power capabilities and required very efficient and powerful loudspeaker systems. The horn loudspeaker was the only existing loudspeaker concept which was able to transfer low electrical power into high sound levels.
Basically, there are two mathematical algorithms for calculating the precise horn shape:
Exponential horns which emerged in the 1920´s, are based on the conception that an even sound wave is emitted at the beginning of the horn. As one part of the sound waves namely that along the central horn axis has to travel a shorter distance than those parts who follow the horn curvature, this theory turned out to be wrong. The wave front within an exponential horn is slightly bent and causes so called colorations, which means changes of tonality during reproduction.
Latest scientific research has shown, that a perfect sound emission can be achieved by using spherical horns. Instead of the 90-degree horn opening of an exponential horn, the spherical horn allows an even transition due to its broad opening of 180 degree. These algorithms are based on the knowledge that the wave surface at the horn throat is not a plane, but is dome shaped.
Spherical horns result in a linear and constant sound wave emission along the entire frequency range. A wide and well-controlled directivity over the entire frequency spectrum is achieved. The spherical horn shows a linear decline at its lower cut-off frequency point. The typical bumpy response of exponential horns does not occur.
The spherical horn curvature is precisely calculated with complex mathematical algorithms. The horns are being produced with an elaborate injection moulding technology. Under a pressure of 2,500 tons a molten ABS resin is injected into a steel mold. These steel molds are manufactured to a precision of ± 0.05 mm – likely the highest accuracy of any spherical horns ever being produced to date. This guarantees a precise propagation of the sound waves within the horn and ensures a stable product continuity during the production process. One horn resembles each other. Left & right channel are always 100% identical.
By accurate computation we enhance the functionality of the spherical horns to work as a crossover filter. This super–crossover has no components and solely works with the medium air. Thus it is totally lossless and free of any artifacts. By defining the horn mouth area we cut low frequencies with 18 dB and with an air volume in front of the horn throat we cut high frequencies with 12 dB.
This way we manage to avoid any passive filter components in the signal path – routing the music signal directly to the voice coil of the driver. Less components, less interactions, less friction ensuring more detail. Perfect!
Our horn drivers are designed in-house and feature a mass-spring voice coil system which is optimized for high forces at low amplitudes. For quality reasons we do not use compression loading in our midrange systems. I.e. the size and shape of the membrane is precisely aligned 1:1 to the throat of the horn. Instead of using compression chambers we rather achieve our high sensitivity with strong magnets and a minimized air gap for the voice coils.
With our Omega–technology we improve the interaction of the speakers with the connected amplifiers and cables. The high impedance of the Omega voice coils increases the damping factor of the system. The amplifier can better control the movement of the drivers. The authority of the amplifier is increased by 450%. The negative effects of long speaker cables is reduced by 80%.
We are very proud of our newest development – the “Soft-Mesh-Compound“ membrane. It uses a stable grid carcass as its structural foundation. The microscopic apertures of the grid are sealed with a proprietary elastic Elastomere–coating. 100% of the additional weight of the sealing is being used to absorb resonances. A special membrane with phenomenal low distortions – a technology breakthrough and for our horns a perfect match.
A horn funnel connected to the front of a speaker driver is the most efficient way to amplify the sound and to increase the efficiency of a speaker. The actual moving parts of a transducer - voice coils and membranes - can be designed much smaller. Smaller moving parts means less weight. This reduction of the inertia of the moving masses will increase the responsiveness of the system. A horn speaker will accelerate much faster and at the same time will come to an immediate stop of motion if induced by the audio signal.
The reduction in the dimensions of the membrane area adds to the mechanical stability of the assembly. This higher sturdiness of the membranes and the reduced amplitude of the driver movement in a horn system will significantly reduce distortions.
Laboratory measurements of our horn drivers with and without the horns executed by Prof. Dr. Anselm Goertz at the University of Aachen impressively endorse the advantages of the Avantgarde Acoustic spherical horn technology:
This means that the usable range from the most silent to the loudest tones is increased by 8 x times. At the same time the Avantgarde Acoustic horn systems have much less distortions and are thus capable of reproducing details which are 10 x times smaller than with conventional box speakers in the box-design.
The horn technology has some incredible technologic advantages. How does this translate into benefits to the listener?
First of all with an Avantgarde Acoustic hornsystem you can listen very loud. You can turn up the volume even more and the sound does not get harsh or aggressive. Even at extreme volumes every-thing remains clear, pure and totally undistorted. The typical buzzing in one‘s ears – you get when playing too high – does not occur. On the contrary: you will find yourself cranking up more often than you used to, because it is simply so much more fun with an Avantgarde Acoustic system.
Secondly you have to envisage that a speaker like – for example the TRIO – is extremely fast. To be precise: in 0,0000125 seconds from 0 to 130dB. That is to say that within a fraction of a blink of an eye air molecules are set into motion with an incredible force. This is an unbelievable acceleration! Every microscopical detail is being reproduced instantly with no lag whatsoever. There is no compression. Zero point zero. No detail is being lost. You will hear details which you have never heard before.
And there is another thing you need to know: in the reverse direction it´s the same. I.e. from 130 to 0dB the speakers needs as well only 0,0000125 seconds. An Avantgarde Acoustic system gets immediately quiet when the music falls silent. No delay, no post-pulse oscillation, nothing! For this reason our horn systems are louder and at the same time more quiet – an incredible experience.
All Avantgarde Acoustic spherical hornsystems are designed with a mass-spring voice coil system which is optimized for high forces at low amplitudes. I.e. even at low and very low volumes every microscopic oscillation of the membrane is translated into clean sound. Just imagine you are doing a meditation or yoga and in the background you have some mantra music playing softly. With the horns you will not hear a sound mush which ripples from far away. You will hear every single tone with a crystalline clarity and power that is capable to penetrate every cell of your body. Amazing.
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