I have heard from many engineers and artists who express their belief that an analog recording has a special magic that has been lost with the advent of the digital age. I don’t disagree, but exactly what that magic is may be misunderstood.
Just like the vehicles that get us from point A to point B, Analog Tape Recorders and The Digital Audio Workstation (DAW) both do the job of capturing and reproducing performances, and they both arguably have their own special characteristics that may make them favorable for a given project.
Analog tape is essentially an oxidized formula that is adhered to a mylar backing. Sound from a microphone or other source is converted into magnetic energy through the “record head” on the tape machine and that magnetic energy is applied linearly to the oxide side of the recording tape. Tape has a limit to its capacity for magnetic energy. The more level sent to the tape machine, the closer you come to that limit. When that limit is reached the reaction of the tape is not abrupt. It is actually quite nicely forgiving at first, as it begins to softly compress your recording. If you push it even harder you might achieve a really neat compression effect. At a certain point though, the tape will give up and the result will be distortion. This may even be desirable occasionally, but generally not and the results are all irreversible!
Another consideration with analog recording is that the magnetic impression that is made onto the tape is not static. It continues to evolve after the initial recording is made. That magnetic impression expands, or spreads spherically. That means the sound spreads forward and backward, softening the transient of the recorded sound. It spreads from side to side causing cross contamination of tracks on a multi-track recording, and narrowing of stereo imaging. And finally it spreads through the layers of tape that are wound together on the reel, causing print through, thus resulting in ghosting of sounds before and after the primary recording. The degree to which this happens depends on the tape formula of the recording tape being used and the amount of level being applied to the tape. You might think that being more conservative with the level is the obvious solution, but it’s a two-sided knife. If levels are too low then excess noise quickly becomes a problem.
When it's done right, an analog recording optimizes the use of the tapes headroom and makes a beautiful recording. The flaws and shortcomings of the analog medium can be perceived as a pleasant and musical glue, or haze, that holds things together and masks blemishes. Clearly, making a great analog recording is trickier than recording to a digital format, and is something that is best accomplished by a professional with years of experience. When an analog recording is done well it has a wonderful, unique quality that may be exactly the right thing for the production.