Living in Nashville I'm very familiar w/'Nashville Tuning'. It's just the 2nd set of strings on a standard 12 string. So, when its played w/a standard 6 string it sounds like a 12 string. The 'Nashville Sound' was developed by Owen Bradley and secondarily by Chet Adkins. The 'flattop guitar' sound was accomplished by having 4 or 5 guitars sitting around 1 or 2 mics all playing the same rhythm strokes on the same chords using capos in differnt positions. For example: Player 1-open A, player 2 Capo 2nd fret using 'G', player 3 capo 5th fret using 'E', player 4 Capo 7th fret using 'D', player 5 using 'Nashville' tuning flattop in open A. That's how they got that 'BIG' acoustic guitar sound on all those Studio B recordings.
By a combination of circumstances...I was being 'courted' as a possible 'Combine Publishing' staff writer at the time. They'd scored a minor hit w/a Glen Campbell cut called 'The Dreams of the Everyday Housewife' by Chris Gantry(RIP) and were looking for 'young/out of the box' songwriters. I got to sit in on a Tammy Wynette session where I met Pig Robbins, Vassar Clemmets, Sneaky Pete Drake, Billy Sherrill and George Jones. I was there for about 3 hours in Studio B and witnessed first hand the recording process at a VERY young age. They were going to let me play one of the rhythm guitars, but at the last minute the missing guitar player showed up. :-( Oh well. Got to shake Tammy's hand...it was a little clammy as I recall. George was sitting on a couch and looked like he was going to explode...I was more than a little afraid of him.
Billy Sherrill couldn't have been more classy and gracious. He shook my hand and said, "You play guitar, son?" I said, "Yes Sir, I do." "You bring it with you?" "Yes." "Well, we're a guitar player short, so would you mind filling in if he doesn't show up?" "No, Sir, not a bit!" "Thank you, son and please call me Bill...everybody else does." Here's Billy 'effing' Sherrill thanking ME like I was doing HIM a favor by agreeing to play...on a Tammy Wynette session! Never forgot how easy going and relaxed he was. I wasn't even in the union!