My last column discussed institutional archives that collect and inventory materials about jazz, in addition to commercial recordings. Yet the most significant musical finds are hidden in private collections, illicitly snapped out of the air by devoted fans empowered by a technology that makes every concertgoer a potential recordist. Some are crooks: They bring radio broadcasts and covert tapes to market, putting them in competition with legitimate recordings and paying the artists nothing. As insidious as the financial chicanery is the seizing of control; performers are no longer in charge of how their work is presented to the public.

In the waning days of the LP, when "bootleg" recordings proliferated, the culprits were denounced with a fury the industry now reserves for those who share files online-to the labels, sales slumps are always someone else's fault. Countless CDs of suspicious provenance continue to confuse consumers. Nor is obfuscation limited to thieves. Consider the second-rate sessions rejected by artists and then posthumously released. Still, if certain pirates and vault-rats are destined for a special ring in hell, how much poorer we would be without dozens of seminal performances privately miked, from Benny Goodman at Carnegie Hall and Duke Ellington in Fargo to Art Tatum anywhere, from Lester Young in D.C. to Miles Davis at the Plugged Nickel and Bill Evans' last hurrah at the Village Vanguard.

Most (not all) of those sessions were paid for and responsibly packaged. But they account for the tip of the iceberg's tip. Over the years, readers have sent me dozens of tapes from a collector's neverland. Sometimes (for example, late-period Wes Montgomery concerts) the music is better than what the legit labels offered; in a few instances, musicians themselves send work of which they are proud yet fear will never be released (for example, David Murray's big-band Ellington). True collectors hoard not out of greed, but from a zealous devotion. Their patron saints include Jerry Newman, who documented the rise of bop, and Dean Benedetti, whose fixation on Charlie Parker rescued snippets of genius on the wing.

Meet two other noble fellows who have devoted time and money to safeguarding the legacies of favored artists: James Brumskin's North Star is Sarah Vaughan and Carl Smith's is Sonny Rollins. Generous with their collections, they will not countenance exploitation without total cooperation of the artist or artist's estate. That may take time, but their treasures abide, implicitly warning history to keep an open mind. Posterity's purchase on both artists must be provisional until these collections are taken into account-whenever that should happen.

Brumskin first heard Vaughan ("If You Could See Me Now") on a record store's street speaker when he was a student at NYU, then arranged to hear her at the Apollo in 1948 and began buying her 78s; as he started to earn a living, he tried to attend her every concert, in time accompanied by recording devices. He eventually accumulated a collection that ranges from Cafe Society in 1946 and the Eddie Condon Floor Show of 1948 to '50s and '60s concerts and broadcasts from around the world. But the real prize is a close documentation of the years 1970 through 1990, the period when she emerged as an international concert star and frequent TV guest, yet formally recorded fitfully (if at all). Here she wails "Bye Bye Blackbird" at a West Side bathhouse, emotes "America" on the bicentennial and dazzles audiences at the Maisonette and Rainbow Room. Brumskin noticed that her annual New York jazz festival appearances attracted the same people every year, and that their increasing responsiveness was reciprocated, encouraging a friskiness absent at other venues. Sound quality ranges from good to barely listenable.

By contrast, Smith's Rollins cache is mostly state of the art, thanks to the development of digital equipment-he uses
CD-R, DAT, MP3 and the most sophisticated playback and copying machinery available. His more than 300 performances, beginning with Rollins on alto in 1948, may constitute the most valuable archive ever assembled on a jazz musician, dwarfing in musical value as well as technical quality even the fabled Benedetti collection-because the disconnect between Sonny live and under glass is so much more extreme than for Parker. A lifelong jazz fan since the 1950s, Smith published a book on Bud Powell (Bouncing With Bud) in 1997, yet had no special interest in Rollins until he attended a galvanizing Boston concert in 2000 that launched him on a mission.

Whenever I review Rollins' astounding New York performances, I invariably receive mail from readers who, dependant on his recordings, question my sanity. Smith's conscientious documentation of Rollins concerts in dozens of cities over the past 30 years preserves the revelatory power of a matchless artist at his peak. He has offered highlights and made samplers for Fantasy Records and Rollins, who has as yet shown no interest in having them released, though he did express pleasure in learning that a particular concert he liked had been taped. The more than 15 hours I've heard represent a magnificent achievement, rare in musical history.

Eric Dolphy expressed the jazz lament: "When you hear music, after it's over, it's gone in the air. You can never capture it again." Sometimes you can; someday we will.