Lenti Acustiche

(Horns: Compression drivers http://education.lenardaudio.com/en/07_horns_2.html )

For circular and near circular horns a lens was the most effective means to increase

horizontal dispersion without introducing lobe distortion and minimal loss of efficiency. An acoustical

lens is the equivalent of the optical lens.

A labyrinth of concave plates is put in front of the horn. Sound from the centre of the horn passes

through unhindered. Sound to the sides of centre in the horn, pass through the lens labyrinth, increasing

the distance traveled and delayed in time. The sound waves are bent forming a wide horizontal

dispersion. The lens improves horizontal dispersion as the frequency increases.

The lens is no longer used. It is large, fragile and expensive. Economic rationalism, not technical

performance was and still is its downfall. Also the lens function was not well understood. Its physical

appearance does not give an intuitive understanding of its function. Many old 60s - 70s roadie sound

engineers believed the lens directed sound downward to the audience sitting in the front row. The lens

was commonly referred to as a waterfall effect speaker. Ignorance and miss-understanding was and

still is a problem throughout the professional audio industry.