The latest batch of music to be digitized came with challenges. This was a pile of tapes, most of which were copies of tapes that in turn were recorded from various albums and tapes, not always in pristine condition. I'm pretty pleased with the job I've done in cleaning them up, which I have mostly done with judicious use of Amadeus Pro's wave-cancelling function. (Sample pure noise, then use that to cancel that noise from the track.) On one hand it's basic acoustic physics; on the other hand, it can be pretty impressive. (Not all noise is kind enough to be cleanly samplable, though.)
This reminded me of the first time I saw that trick in action:
On the Mark was privileged to work with several excellent sound engineers over the years. Mike, who recorded our later CDs, had built his studio in his home. We learned through trial and error that, especially for instrumental tracks, we made our best music by all playing (and listening) concurrently, rather than laying the tracks down one at a time with headphones. (We found it especially difficult to do the one-track-and-headphones trick for wind instruments, including voice -- being able to hear the sound you are making in the room, and not just back through the system, was critical for some of us.)
So we were recording some instrumental pieces, I no longer remember which, with everyone miked individually but not completely in isolation. Yes it limits what you can do in post-processing, but we'd done this before and it had worked out well. We knew not to mix or post-process on the day we record; for me at least, the ears are tired by then and the brain is still full of what you just heard live. Mix-down was always on a separate day and without most of the band there.
So, we had this great recording session, and some days or weeks later Mike and I sat down to refine it. And on one song, so faintly we didn't notice it at first, there was a strange sound. One by one we isolated the tracks until we found it on a recorder track recorded by Alaric.
What was that? It didn't sound like it was coming from the recorder or its player. It was not, in fact, coming from inside the room. The studio had pretty good sound insulation, but some things you just can't plan for: the sound was a helicopter that had been passing overhead and had managed to bounce sound into the house just so.
The recording was otherwise very good, so I wanted to try to save it. My first thought was to replace the recorder track (the helicopter was not audible on any of the other tracks), but Mike pointed out that this would alter the sound of the whole because of the way we'd recorded it. But he had a related solution.
So we brought Alaric back in to record that track again as precisely as he could (listening in headphones). He nailed it. And then Mike did the following: he used that recording to remove the recorder from the original track, used the rest of the mix to remove all other music from the original track, and used the result -- which was now helicopter and nothing else -- to then remove the helicopter from the original track. Ha!