Your 1939 date is probably correct. The four tubes on the upper part of chassis are 8 pin octal which were introduced in the late 1930's. The big boy on the bottom is probably the rectifier tube and most likely a Type 80 four pin tube.
Correction....looking at the underside picture the rectifier is also an octal so it's most likely a 5U4.
That's what I recall it being, a 5U4. I'm really strongly leaning towards 1939 on it too, so I'm really not sure I understand the newspaper article talking about how the company loved being in Arnprior as if their move there was recent in the fifties when they clearly had been there for a while by then. Maybe it was just a local boosterism piece featuring one of the area companies?
Look at the neat cabling and lacing job on that, someone took pride in that.
It really is nicely built. They don't build them like that anymore and the don't build them here anymore.