Electrostatic

Nearly all loudspeakers currently use the age old 'dynamic' principle of a coil in a magnetic field pushing a cone or dome back and forth to produce sound. The moving parts are slow, heavy and very prone to producing unwanted vibrations of their own.

By contrast, with an electrostatic loudspeaker;

• The diaphragm is driven by the same electrostatic forces that make your hair stand on end when you rub a balloon and hold it near your head.

• The diaphragm is incredibly light and responsive (six times thinner than human hair) – it is the closest thing to moving air directly without any kind of mechanical structure.

• The diaphragm produces no unwanted vibrations because it is damped by the grille cloth at low frequencies and by the air load at high frequencies.

• The mechanism is almost perfectly linear so the sound isn’t distorted.

• There is no box to spoil the sound.

Oscillating Sphere concept

Unlike other electrostatic loudspeakers on the market, FrontRo uses an innovative concept to prevent the waves from beaming towards you: The Oscillating Sphere. Imagine a rigid sphere oscillating back and forth in free space, spreading the sound out in all directions across the entire musical spectrum. This is the perfect dipole sound source and has a smooth response.

To imitate this, using a flat diaphragm, the FrontRo electrodes are divided into concentric rings, which are fed from a delay line. Hence the sound radiates from the center first and then from each successive ring until it leaves the outermost ring, by which time the sound from the center is some distance from the diaphragm. Hence a hemispherical wavefront is produced, which spreads out like ripples in a pond. Unlike previous arrays, this one does not need losses in the delay line (or shading) to smooth its response, which increases its efficiency and thus enables a more compact design. To allow the sound out, the pattern of holes in each electrode is the same as that of the seeds on a sunflower head. It turns out that nature has found the most effective way of packing circles within a circle! For further information, the paper entitled 'How do we make an electrostatic loudspeaker with constant directivity?', which describes the oscillating sphere principle, is available for download from this website.