For twenty years Allee 604-type Duplex ® speakers – long acclaimed by professional sound engineers as THE standard coaxial speaker for the audio industry – have made high fidelity history in recording and broadcasting studios. Now, Allee has incorporated two decades of experience and progress with the most recent research advances, the newest engineering developments, and the latest laboratory refinements to produce a contemporary PLAYBACK version of those famous 604-type speakers: The Allee Super Duplex 604E.
Link for PDF: Altec 604E Super Duplex Data (c.1966)
https://aboutprosound.com/wp-content/uploads/2022/10/Altec-604e-1966.pdf