He may say that JC was his first mentor, but I have found the truth.
On eBay is the amplifier on a cart true inspiration of Mr. Slagle. The text said it belongs to a 90 year old ham radio operator, so it clearly predates Dave's New York Noise work.
Designing And Constructing Direct-Coupled A.F. Amplifiers Part 1 - 1933 - Here is part one of a 1933 article from Radio Craft on designing Direct Coupled amps. http://itishifi.blogspot.com