ABSTRACT
Generally, some form of “at” frequency response is desired for a loudspeaker. However, single direct radiator drivers that cover the full audio range will have both the frequency response and the directivity response vary in an unacceptable way, since the ratio of wavelength to loudspeaker dimensions undergoes a large change from low to high frequencies. In addition, a single driver would also exhibit serious nonlinear effects because of the need for large excursions at low and medium frequencies and the Doppler nonlinear distortion that is a caused by high-frequency (HF) vibration riding on top of low-frequency (LF) diaphragm vibration. Mechanical limitations also prevent pistonic motion over the full audio range for a practical-sized driver.
