Which nine-time Grammy Award-winning gospel group helped found the National Quartet Convention?
National Quartet Convention:  J. D. Sumner, Cecil Blackwood and James Blackwood of The Blackwood Brothers were the founders of the famous National Quartet Convention formerly held in Memphis, Tennessee. The Blackwood Brothers: The Blackwood Brothers are an American southern gospel quartet. The Blackwood Brothers:  They are nine-time Grammy Award-winning pioneers of the Christian music industry.
The Blackwood Brothers