I've been doing some digging myself and have slowly started compiling a list of unreleased however announced Quad mixes. Some new additions include:
Simon & Garfunkel - Bookends (the engineer Jim Reeves claims to have mixed this one)
Laura Nero - Christmas and the Beads of Sweat (another Jim Reeves mix, also we've located Eli & the 13th Confession)
Sly & the Family Stone - There's a Riot Goin' On (found a vintage magazine article mentioning this title coming soon in Quad)
Joe Walsh - So What (another forum claims to have found the QS master tape)
Supertramp - Crime of the Century (another magazine list of tapes supposedly available now!)
Ringo Starr - Ringo (tape slickers showed up on eBay a long time ago)
James Gang - 16 Greatest Hits (another vintage magazine article mentions this)
and then of course, the ones that have been located on Quad reel like Edgar Winters White Trash, Raiders Hard & Heavy, Big Brothers Cheap Thrills....
Simon & Garfunkel - Bookends (the engineer Jim Reeves claims to have mixed this one)
Laura Nero - Christmas and the Beads of Sweat (another Jim Reeves mix, also we've located Eli & the 13th Confession)
Sly & the Family Stone - There's a Riot Goin' On (found a vintage magazine article mentioning this title coming soon in Quad)
Joe Walsh - So What (another forum claims to have found the QS master tape)
Supertramp - Crime of the Century (another magazine list of tapes supposedly available now!)
Ringo Starr - Ringo (tape slickers showed up on eBay a long time ago)
James Gang - 16 Greatest Hits (another vintage magazine article mentions this)
and then of course, the ones that have been located on Quad reel like Edgar Winters White Trash, Raiders Hard & Heavy, Big Brothers Cheap Thrills....
