The speaker unit which was completed in Showa 22 and adopted as the NHK
monitor by the Diatone by joint development with the NHK group of technical
It is displayed as <first monitor speaker in
domestic production> in the broadcast museum in Atago-yama.
Corrugation was adopted, and it was made as No. 1 of a consistency
vibration type full-range speaker original with a Diatone, and became a
prototype of P-610.