The analog sound

Although the entire media world is turning to digital technology over analog, analog tape recorders still remain as highly-prized tools of the top-class professional recording studio. In such studios, recordings can still be made on analog tape.

There are two reasons why digital recording has become the norm elsewhere:

• It's cheaper - much cheaper!
• It isn't subject to the same flaws of analog recording

When digital recorders first became available in the early 1980s, engineers and producers couldn't wait to get their hands on them; they were so sick and tired of the problems of analog.

There are three characteristic ingredients of the analog sound:

• Distortion
• Noise
• Modulation noise

Distortion is a changing of the shape of the waveform, like a fun fair mirror distorts the reflection compared to a flat one that doesn't. Distortion in audio adds frequencies that were not present in the original signal.

Noise is caused by random variations in the medium, in this case the random orientation of the poles of the magnetic domains on the tape.

Modulation noise is noise that changes in level as the signal changes in level. The ear can often ignore steady-state noise, but modulation noise continuously draws itself to the listener's attention.

In the heyday of analog, these were all seen as problems, and digital recording virtually eliminates them for all practical purposes.

However, we now have a choice. We don't have to use analog if we don't want to, therefore the 'flaws' can now be seen as 'features'. It's a different way of looking at it.

Now, we perceive a little distortion as 'warmth'. Most of the distortion produced by analog recording creates frequencies that are musically related to the input frequencies and correspond to the harmonic series of string and wind instruments. Warmth may not a bad thing at all, compared to the clinical precision of digital recording.

Noise is hard to perceive as a good thing, but look at it as the equivalent of the varnish an artist would apply to his or her oil painting. Without the varnish, the painting might be pretty, but the varnish draws all the colors into the same 'space' and suddenly we have a work of art. OK, that's a fanciful analogy, but many engineers would agree that it is easier to mix a multitrack recording made on analog tape. The noise background may have something to do with that.

Modulation noise is the tricky one. This is certainly a feature of analog recording. It's hard to justify why it might be good, but digital analog simulators that do not simulate modulation noise don't really sound like genuine analog technology. We don't know why, but modulation noise is giving us something we like.

At the end of the day, the analog tape sound is the sound of recording, from the 1950s right through to the 1990s and beyond. It's something that we all grew up with, and we have learnt to like it.