Was "Route 66" audio high quality for the era?

[brassplyer]

I've been going through the original Route 66 series - it seems the audio is really good for the era. It's mono of course but the audio is really clean - in particular the opening and closing themes and any time there's music playing I get the sense there's more fidelity than I'm used to from shows of the time where the target was a tv speaker.

Was there something different about the production of that particular show or is it just that the masters are really clean and more of the original quality is intact vs typical OTA broadcasts?

[smrpix]

Audio for decent TV shows and movies of that era were edited and mixed on 35mm magstripe tape or 35mm mag fullcoat. (Basically 35mm film with magnetic "tape recorder" tape on its surface.) Network shows in particular were often originally broadcast with the fullcoat interlocked with the 35mm picture and were capabale of very high quality audio. That is not to say modern electronics haven't entered the process as well.