Dont Look Back (1967)

From this Rolling Stone article:

...it's the audio restoration that genuinely makes the new DVD/Blu-ray stick out, thanks to a painstaking process that would help correct earlier mixes of the movie, which tended to employ a "fake stereo" set-up that panned the mono tracks. (Listen to the "Subterranean Homesick Blues" opening on previous DVD releases, and you can hear the bass line bouncing back and forth between your speakers.) That meant going back to quarter-inch magnetic master tapes in Pennebaker's vaults — what Criterion audio supervisor Ryan Hullings calls the "holy grail" of Don't Look Back materials. "D.A. had stored them properly since day one, so they were in excellent physical condition," he relates via email. "The problem was that those tapes used a special version of Fairchild Sync, which was only used for a very, very brief time in the mid-Sixties...and modern tape heads can't read it. I looked all over New York for someone who could transfer the audio, so I wouldn't have to ship these priceless materials out of the state, and no one could play them."

Salvation came in the form of Peter Oreckinto, a former Kiss roadie living in Los Angeles who had a reputation for being "an analog film-audio guru." Hullings sent him the masters and crossed his fingers; the West Coast resident then built his own bespoke tape head from scratch that could read the outdated signal. "He sent back an audio sample as a test," the Criterion employee recalled, "with a note that said 'I have no idea whether this will sync up, but give it a shot.' We were floored by how amazing the recordings sounded — and it synced up perfectly with the picture!"

 "It actually changes the movie," Hendrickson says, in regards to the restored sound. "Take the Donovan scene: It has always been read as this big takedown, with Dylan taking the guitar and trying to one-up the singer. But now, you can actually hear Donovan ask Dylan to play 'It's All Over Now, Baby Blue' for him — it changes the intention of the scene entirely. It's not nearly as negative! All of us in the office were watching the movie right after we put the sound track in and we suddenly, Wait...did he just request the song?!? And none of us could remember hearing that before."

Firstly, the audio track on the Criterion blu-ray, made from the 1/4-inch magnetic tapes, does sound a lot better than the track on the Docurama blu-ray, which was presumably sourced from optical elements. The old track definitely has some duophonic fake stereo BS going on, occurring throughout the entire film, and the new track is simply more detailed.

I disagree, though, that the new track "changes the movie" -- this is marketing hyperbole. Donovan's request can absolutely be heard on previous versions of the film, which I can say without directly comparing the two tracks: I've heard the line every time I've watched this over the years.