From Ben Ratliff's Coltrane: the Story of a Sound. Many of the recordings were made at Philadelphia's Showboat in the early 1960s. It's all live performances of the classic quartet, although I think some have Roy Haynes on drums instead of Elvin (presumably from the stretch of 1963 when Elvin was out of commission). I have a couple of CD-Rs that someone sent me many years ago that includes Coltrane playing "After The Rain" on piano iirc. Guessing that audio technology 25 years on is more capable of improving the sound quality than it was when digital transfers were made in 2000.
Tiberi noticed a big difference in Coltrane in 1960… Not wanting to let this pass undocumented, Tiberi started bringing a portable reel-to-reel tape recorder into clubs to tape Coltrane’s sets… His tapes are important evidence of what Coltrane was up to at the beginning of his bandleading… When Verve records made a digital transfer of Tiberi’s tapes, in 2000, they amounted to eighty-six CDs. The sound quality, however, was deemed (by Tiberi as well as Verve) not to be good enough for release. And so an important part of Coltrane’s story remains locked up, for now.
- Ben Ratliff, Coltrane: the Story of a Sound