A speaker system comprises a pair of speakers for a higher frequency range and a pair of speakers for a lower frequency range. The speakers for the lower range are disposed with a space d.sub.1 equal to the wavelength .lambda..sub.c of a division frequency f.sub.c of a reproduction frequency range, and...http://www.google.fr/patents/US4991687?utm_source=gb-gplus-shareBrevet US4991687 - Speaker system having directivity
