Vox 1970 full line catalog. page 14. Details of the Gyrotone II, III, 50 and 100.
The Gyrotone II is described as follows:
Take your sound and hurl it into the fifth dimension. Give it body, depth, length - a whole new shape. The Gyrotone II. Secrets of 'wrap around' sound that will send your audience into a whole brave new world. Two speed. Two 12" full range main speakers and one 12" Gyrotone speaker.
whilst the Gyrotone III is described like this:
Take your sound to places it's never even dreamt about. Stretch it. mould it. throw it out the way you want it. The Gyrotone III. The big one. Two speed. Two heavy duty 12- full range main speakers. One heavy duty 12" Gyrotone speaker.
The Gyrotone 50 and 100 were equivalent to the Gyrotone II and III respectively, with Midas 50w and 100w amplifiers (see page 18) built in.