1930 Advert From Listener-In Magazine

Air-Master Dynamic Power Console
Embodying many exclusive features for which the most expensive Air Master models are famed;including something very special in Dynamic Speakers, this fine Radio instrument creates Radio value hitherto onheard of, and, at the same time, sets a new quality standard in its class.
A magnificent model in all essentials of performance.
"Taken From 1930 Advert"

Air-Master "4 in Seven"
Marvellous! Magnificent! Remarkable! And a score more superlatives might well be added! Of the 7 valves 4 are screen grid; imagine the result obtainable, especially on distance. imagine the mellow depth, the velvet resonance, the singing sonority assured by Dynamic reproduction.
"Taken From 1930 Advert"