Complex sentence: The company was founded in 1973, when Concord, California based auto dealer/jazz enthusiast Carl Jefferson, produced the first Concord Jazz recording by jazz guitarists Herb Ellis and Joe Pass.
Split into simpler sentences: The company was founded in 1973 in Concord, California by Carl Jefferson, an auto dealer and jazz enthusiast. Jefferson produced the first Concord Jazz recording by guitarists Herb Ellis and Joe Pass.