When licensing rights to the Rykodisc label for Frank Zappa's huge back catalog expired, something curious happened. The music disappeared. Now that might not spell the end of the world for your average Justin Bieber or Nicki Minaj fan. But for anyone unacquainted with the wildly adventurous music Zappa created before he died in 1993, it meant all means for discovery and exploration were closed.

The Zappa Family Trust retained ownership of the recordings. But until a new licensing agreement could be struck, those albums remained out of print and unavailable.

As of this week, Zappa's first 12 recordings became available again as part of a new licensing deal with Universal Records: Freak Out!, Absolutely Free, We're Only in It for the Money, Lumpy Gravy, Cruising With Reuben and the Jets, Uncle Meat, Hot Rats, Burnt Weeny Sandwich, Weasels Ripped My Flesh, Chunga's Revenge, Fillmore East June 1971 and Just Another Band From L.A. All are solo works along with the formidable experimental pop pieces forged with his band The Mothers of Invention.

Hardcore Zappa fans need not apply. The Universal reissues contain no extra tracks and no discernible remastering; your old Rykodisc editions are sufficiently definitive. But for a new generation acquainting itself to Zappa, this is a momentous occasion. A serious adventure awaits you.

This initial set of 12 albums — released in rapid succession from 1966 to 1972 — represents all the innovations and idiosyncrasies that made Zappa a revered pop figure. Early Mothers works like Freak Out!, Absolutely Free and especially We're Only in It for the Money and Uncle Meat set the pace. All were montages that mixed grand pop tradition (with Zappa's roots in doo-wop surfacing repeatedly), social commentary (which, more often than not, morphed into bitter satire), neo-classical compositional structure (that regularly spilled over into the avant garde) and, of course, a whale of a guitar voice.

The turning point was 1969's Hot Rats, the brilliant, predominantly instrumental (save for a fascinating Captain Beefheart cameo on Willie the Pimp), that highlights a compositional style built around animated — almost to the point of being cartoon-like — melodies and lengthy jams that took Zappa closer to progressive jazz turf.

Burnt Weeny Sandwich and Weasels Ripped My Flesh remain overlooked gems, in which the Mothers fell in line with Zappa's post Hot Rats sound. But Fillmore East and Just Another Band From L.A. (both concert recordings from 1971) reshuffled the Mothers lineup into a bawdy carnival act with ex-Turtles Mark Volman and Howard Kaylan (known then as Flo and Eddie) as ringmasters.

Imaginative, playful and maybe a touch offensive in spots, these were the recordings that introduced and defined Zappa's masterful pop intellect. How wonderful to have them among the living again.

Read Walter Tunis' blog, The Musical Box, at LexGo.com.