Omnidirectional folded horn
Micro-level precision and great dynamics of front-loaded horns are unbeatable by direct radiation speakers. But there are also some typical horn disadvantages: the directivity pattern is normally quite sharp, and the operating frequency range usually doesn't exceed 3 octaves. Directivity can be corrected by special horn mouth design, or by acoustical lenses, but the frequency range is limited by physical horn principles, so that separate horns are to be used for each frequency band in multi-way systems.
We were challenged to design a omnidirectional front-loaded horn, that could operate almost in the full frequency range, from around 100 Hz, and up to 20-25 kHz. Resulting spiral-shaped folded design of the A-1 loudspeaker was protected by Russian patent in 2008.
This is a parabolic front-loaded horn, folded like a spiral, so that an almost cylindrical wavefront is produced. In addition, parallel walls of the folded horn build a waveguide, where the frequencies up to 25 kHz can propagate. This structure offers all horn advantages like great sensitivity, high acoustical load to the driver, but is omnidirectional and covers 8 octaves!