Does this answer your question?
http://www.americanradiohistory.com/...o-1955-Oct.pdf
He tells you in the #1 post where it can be found, I thought everyone knew about The American Broadcast History website. If not then be prepared to get lost for days, weeks or years. Loads of magazines there including Wireless World, ETI, Practical Electronics, Radio Constructor, Tape Recorders and tape recording, that is just a small sample.
The Audio Engineering magazine this came from has lots of circuits it moves away from DIY in the early/mid 1960s.