My feeling is that Reeves did mix everything he claimed he did, it was just that CBS seems to have done multiple quad mixes of some of those early releases, possibly because they hadn't settle on SQ as their LP delivery format of choice and had to go back and make them compliant. Thanks to the Robin reels and the AF SACD release of Laura Nyro's Eli and the Thirteenth Confession album, we know that there are at least 3 quad mixes of this album, with the early ones (the Robin reels) having material mixed center-back (a SQ no-no) and the later version (the AF release) having the rear speaker elements pushed hard left and hard right.
Also take for example that John Cale (formerly of the Velvet Underground) was hired to oversee quad mixes for CBS for a while in the early days, and he only ended up with one quad supervisor credit: Poco's Deliverin' album. I find it hard to believe that he only showed up to do that one mix. What else did he work on?
I don't have the article to hand, but I recently found a story in a Billboard magazine from 1972 where a CBS rep said they'd mixed lots of stuff in quad starting in 1968, but "deliberately held it back from release" until they found (what they thought was) an acceptable LP delivery system in SQ. These releases didn't happen until January of 1972, so I think there was a lot of stockpiling going on. In addition to the Robin reels, and other unreleased things mentioned in advertisements and other print media, there were also samplers that had tracks from Al Kooper's I Stand Alone album, a Mongo Santamaria track from an album he did for CBS before he left for Atlantic, and many others. I feel like these were from full albums mixed for quad rather than tracks just mixed for quad from samplers. Whether I'm right or not, and even if these things could even be found or not remain to be seen, but the prospect is tantalising to say the very least.
Also take for example that John Cale (formerly of the Velvet Underground) was hired to oversee quad mixes for CBS for a while in the early days, and he only ended up with one quad supervisor credit: Poco's Deliverin' album. I find it hard to believe that he only showed up to do that one mix. What else did he work on?
I don't have the article to hand, but I recently found a story in a Billboard magazine from 1972 where a CBS rep said they'd mixed lots of stuff in quad starting in 1968, but "deliberately held it back from release" until they found (what they thought was) an acceptable LP delivery system in SQ. These releases didn't happen until January of 1972, so I think there was a lot of stockpiling going on. In addition to the Robin reels, and other unreleased things mentioned in advertisements and other print media, there were also samplers that had tracks from Al Kooper's I Stand Alone album, a Mongo Santamaria track from an album he did for CBS before he left for Atlantic, and many others. I feel like these were from full albums mixed for quad rather than tracks just mixed for quad from samplers. Whether I'm right or not, and even if these things could even be found or not remain to be seen, but the prospect is tantalising to say the very least.