I have a feeling that Doc's sound is due to Doc. I'll wager he can get it with any guitar that doesn't stand up and fight him. He does have a beautiful sound which sometimes gets forgotten in the admiration of his facility.I have read that Merle Travis owned a Martin acoustic guitar with a custom-made fancy headstock. Are there any recordings of him playing that. In all the recordings I have heard, he seems to be playing an electric guitar.
Murray