Yamaha #10
october 2004
JA-6002
JA-5002
(c. 1968 [?] - 1974)

REVOLUTIONARY NATURAL SOUND SPEAKER
These strange forms are speakers of a very new type, functioning on the same principle as the sound board of such instruments as pianos and violins and producing beautiful sounds in all their natural loveliness.

The sounding board of the piano provided the hint for the development of the Yamaha Natural Sound Speaker. It is a multi-dimensional sound system in which sound waves are harmoniously mixed and composed. The sound direction does not concentrate in the center but spreads dynamically in all directions.

The large aperture voice coil and the efficient Yamaha Columnar Crystal Magnet make the speaker resistant to large power input and the whole system displays extra high performance. The large plastic diaphragm is manufactured under rigid quality control, with less unevenness of characteristics, more excellence in durability, and absolute freedom from outside humidity.
For frequencies above 1KC, however, an emphasis circuit of about 3dB/oct. should be used. An open-back cabinet is recommended. For the JA-5002, a baffle board with 2-3 times larger area, including the sides of the cabinet, than the diaphragm will provide better low sounds.

The TSN versions of both JA-6002 and JA-5002 included a high-frequency speaker and an LC filter for which I have no literature or description.