Every so often, greedy (or is it desperate?) record companies dip into their overmined vaults and rejigger classic albums, fiddling with the sound a bit and slapping on a ''remastered'' sticker in a cynical bid to ensnare music fanatics. This is not one of those times.
Columbia has finally gotten around to revamping the Bob Dylan catalog, and the results are pretty spectacular. On Sept. 16, the first batch of CDs hit stores: 15 beautifully packaged discs spanning his entire career, including a handful of certified masterpieces: ''The Freewheelin' Bob Dylan,'' ''Bringing It All Back Home,'' ''Highway 61 Revisited,'' ''Blonde on Blonde,'' ''Blood on the Tracks.'' (A second group, ''The Times They Are A-Changin''' and ''New Morning'' among them, is due next year.)
Although high-end-audio buffs will get their geek on playing back the titles in the hybrid super-audio (SACD) format (six of the discs are also available in a 5.1 surround mix), what really matters is how they sound on a conventional stereo system. And they sound fantastic. Dylan's mid-'60s records benefit most from the retooling. Fans accustomed to the murkiness of the original ''Highway 61'' and ''Blonde on Blonde'' CD transfers will be astonished by the power and clarity of the upgrades. Cymbals ping with new brightness, guitar sounds are clearer and more distinct, and full-bodied piano leaps out of the mix like never before. Check out the percussive piano on ''Like a Rolling Stone'' (from ''Highway 61 Revisited''), which has gone from barely discernible background color to a lead instrument. Or what turns out to be delicate bass-drum work on ''Visions of Johanna'' (Blonde on Blonde). ''She Belongs to Me'' (''Bringing It All Back Home'') becomes almost a duet between Dylan's voice and some gorgeously subtle guitar playing.
There's also drastically improved separation between the instruments, making audible every detail of what's being played. (The effect is so pronounced that some listeners might find it initially distracting.) Post-'60s classics like ''Blood on the Tracks'' and ''Oh Mercy'' also enjoy a significant sonic boost, revealing new details and nuance. (The crisp attack of the intricate twin guitars on ''Blood'''s ''You're a Big Girl Now'' is breathtaking.) So while fans will groan at the prospect of shelling out again for CDs they already own, it's worth it. These remasters really will change the way you experience the music. Who'd have thought that ''Blood on the Tracks'' could get...deeper?
So when are they gonna do the same for the Bruce Springsteen catalog?