The first SR-Λ (lambda) series was introduced 30 years ago, and now the SR-307 and SR-407 have adopted the same sounding body (sound element) as that of the top model SR-507.
The conventional sound element has employed simplest structure so that as wide film diaphragm area as possible can be effectively used in comparison with its external size. Taking advantage of the conventional feature, the new sound element has been packaged in a tough resin case. Thus the new sound element has realized cleaner sound and better reliability. Also a new thin-film material (super engineering plastics) almost free from stretch through temperature or humidity has been adopted, enabling both the rich, deep low frequency and the delicate high-frequency sound.