JD Sumner with the Blackwood Brothers - Hide Me Rock Of Ages - 1960 (featuring very low bass) 

"Hide Me Rock Of Ages" performed by The Blackwood Brothers featuring JD Sumner's incredibly low bass voice and breath control in 1960. JD goes to a vocal fry A0 at the very lowest.
I combined two recordings :
1st : at 1:05:25 • JD Sumner A Musical Bi...
2nd : at 1:17:10 • Through The Years with...