Cogito wrote:
Again from Altec literature:
Quote:
A characteristic feature of the sectoral horns is a beam width in the horizontal plane that is constant through the middle and high frequency range. Other horn types (except the multicellular horns) passes beams that become progressively sharper as the frequency increases, and generally cover a narrow area at the high frequencies.
Probably directionality of the higher frequencies is the reason almost all the direct radiating speakers have very small sweet spot for soundstage imaging.
I am not suggesting that sectoral are better than other horns or speakers of any other kind. Just trying to understand. What sonic characteristics of sectoral (not just 511Bs) horns is considered flawed?
In diffraction horns, diffraction is used to "spread" the sound. However, a diffraction is an impedance discontinuity. It causes reflections that reach the listener at different times, smearing the image, just as sharp edges at the edge of a baffle do. Impedance discontinuities also cause reflections back to the diaphragm and what that entails. If looking for controlled directivity as a priority, the Geddes OS waveguides or Minphase horns offer that with the least amount of diffraction.
The same goes for the horn's mouth. Large roundovers minimize impedance discontinuities. They will be delayed longer when reflected back to the diaphragm. However, according to Geddes, impedance discontinuities (changes in slope) near the throat are more detrimental to creating High Order Modes (HOMs) that are basically sound waves that, by bouncing around in the horn, take a longer path to your ear.