No.1 in Sound Output: Sound Delivered to 12km Away
In 1962 TOA manufactured an unprecedentedly large-output amplifier and two enormous horn-type speakers with a three-meter diameter. We conducted a broadcast experiment on the coastline at Akashi in Hyogo Prefecture and confirmed that the sound was delivered to Awaji Island 12 km away. To TOA's knowledge, this was the world's loudest sound ever output from a sound system.
The maximum output of 4,200W achieved by use of a cutting-edge transistor when vacuum tubes were in full swing
The development of this system was triggered by an inquiry from a customer abroad about a broadcast system for political publicity. The customer's requirement was to deliver propaganda to the other side of a river, which was 12km away.
In order to satisfy this requirement, we used a transistor for the amplifier. At that time, transistors were cutting-edge devices and the price of one transistor was about the same as the average monthly starting salary in Japan. When the maximum output of a sound system for a movie theater was about 20W, our system realized an extraordinary output of 4,200W.
Although this project did not materialize, the technologies we developed then have become core technologies underpinning our subsequent development of large-output sound systems.