The Second Disc remembers Mark Volman, 78, co-founder of The Turtles, one half of Flo & Eddie, unforgettable member of Frank Zappa’s Mothers of Invention, author, radio personality, and artists’ rights advocate.  With his longtime musical partner Howard Kaylan, Mark lent his soaring vocals to recordings by such artists as T. Rex, Bruce Springsteen, Alice Cooper, and many others.  A bright, colorful, and cheery onstage presence, Mark continued to perform with The Turtles following Kaylan’s 2018 retirement, spreading the fun of “Happy Together,” “Elenore,” and “You Baby” with delighted audiences across the…