Digital recording has revolutionized several creative industries, from film to pop music. It has reshaped markets and enabled tens of thousands of indie artists to reach new audiences without having to sell their souls to record labels.
This shift has been driven in particular by the rapid decline in the cost of music production tools. Today, the planet is dotted with home studios, each one brimming with hope that the music produced inside of them could be the next big thing. Bedroom producers predominantly rely on software to emulate physical gear in a digital environment, rather than using actual, much more expensive hardware.
Digital recording, however, has one subtle drawback—it can sound somewhat sterile, almost lifeless. This is true even when traditional "live" musical instruments are used in the recording.
In the early days of digital recordings, this was something almost everyone could notice, from music producers down to everyday listeners who weren’t necessarily well-versed in the intricacies of music production.
Music industry professionals weren’t satisfied with this sterile sound, of course. Something had to be done. They quickly realized what was missing from the digital recording process. Oddly enough, it was the very imperfections introduced by traditional analog studio equipment.
This applied not only to tape machines but also to analog mixing consoles, tube preamps, certain types of microphones, and more. Tape machines, however, were always present in the signal chain, without exception.
Additionally, a lot of recordings were made using multiple layers, where previously recorded musical segments were re-recorded onto new tape two or three (or sometimes even more) times. This "layering" technique was heavily employed by the legendary band Queen. The Beatles' iconic album Sgt. Pepper’s Lonely Hearts Club Band was one of the first recordings to make complex use of this overdubbing technique.
At every stage of the music layering process, tape recorders added complex distortions. And, in the final product, these musical colorings added up to something more complex.
Over decades and decades of pop music production, both music producers and listeners have developed a kind of culture of creating and revering such recordings.
As such, in the era of digital recording, there emerged a commercial and creative demand for software solutions that would mimic the work of analog equipment during tracking and mastering.
And that demand was met quite quickly. Audio plugins appeared that could plausibly emulate the work of studio tape machines. And here's what modern music software tries to do…
The exact reason why Homo sapiens likes distorted sounds remains unknown, although there are some interesting hypotheses. Either way, it has been fairly well established that people pay more attention to distorted recordings.
In 2012, for example, researchers from the University of California conducted an experiment in which they asked listeners to assess how "exciting" they found a series of 10-second music clips. They were asked which ones evoked positive emotions, which ones evoked negative emotions, which ones energized them, and which ones made them sad.
One group of participants listened to music that started out light but suddenly had distorted sound, while another group listened to pieces that were light throughout. A control group only listened to calm music. Later, the experimenters made the task more difficult. Video clips began to be shown to the participants along with the music.
The subjects unambiguously characterized music with distortion as more exciting than tracks without distortion, and also as "negatively charged." If they were played music in combination with boring videos, they no longer felt that the music was "exciting," but they still believed that it carried some sort of "negative charge."
The authors of the study explained that music with distorted sounds has a set of common sound characteristics with the voices of worried animals. To convey anxiety or fear, they quickly pass a large amount of air through their vocal cords, which causes the sound to have "distortion."
Scientists suggest that the human brain may respond to it with excitement because evolution over numerous generations has taught us to pay attention to such cries. "It awakens our inner animal," co-author Greg Bryant noted.Another study, conducted in England in 2015, showed that listeners unambiguously perceived music with distortion as louder.
It's no surprise then that producers wanted to bring back the quality that analog equipment previously brought to digital recording.
In short, a traditional studio tape recorder introduced the following distortions into a recording: soft clipping, slight compression, adding additional harmonics to the signal, softening the rumble of low frequencies, softening the sharpness of high frequencies, and slightly lifting the upper midrange.
And here's what happens to the music and tape recorder in the case of clipping: the analog electric signal coming into the device is converted by the recording magnetic head into a variable magnetic field.
Its sphere of action captures the moving magnetic tape. It is covered with ferromagnetic powder in a special lacquer. This layer has magnetic properties, and a trace of residual magnetization remains on it. This is actually the track of the phonogram.
When we increase the recording level on the tape recorder beyond the limit of 0 dB, the input voltage exceeds the capabilities of the system and/or the saturation threshold of the tape with magnetic potential.
Or, simply put, the particles of iron oxide, which make up the magnetic powder, cannot be polarized (magnetized) stronger than they already are. And so the trace of magnetization on the tape is not capable of "absorbing" a higher amplitude of the audio signal.
Our analog music signal is a complex sum of sine waves. Each one is like a uniform "wave" consisting of "hills" and "valleys."
When the input audio signal exceeds the system threshold, on the recording made by the magnetic tape, the "hills" and "valleys" of the peaks and troughs are cut off, and the signal spikes take on a trapezoidal shape.
To the ear, this is perceived as a slight wheezing in moments of peaks - for example, bass drum hits or snare snaps. It is this effect that both listeners and music producers like.
Also, compared to digital sound recording, recording on a tape machine has a lower dynamic range. That is, magnetic tape brings a small amount of compression to the signal - as if making loud sounds a little quieter and quiet sounds a little louder. This effect is also part of the "culture of music recording."
Amazingly, the imperfections of tape machines as engineering devices became part of the culture of music. Unintended effects such as Wow and Flutter, also known as "Warble" became a large part of it, too.
These effects are caused by the uneven movement of the tape along the magnetic head. The Wow effect is noticeable at lower frequencies, and Flutter is noticeable at frequencies above 1000 Hz. At their core, these are really just recording defects, but they became such a big part of musical culture that now they are very carefully used to enliven sterile digital recordings.
Other distortions were introduced into recordings by various different studio tape machine models. Saturating the sound with additional harmonics is another example.Each tape recorder had its own sound "character," which was reflected in the artistic side of music production. Some models have become truly legendary. For example, the Swiss model Studer J37, built by one of the pioneers of sound recording, Will Studer.
Modern tape machine VST and plug-ins of other formats try to imitate the work of studio tape recorders. There are also emulators of domestic and even cassette decks.
Many of them successfully reproduce all the effects of tape machines using complex algorithms, including even BIAS - the addition of ultrasonic frequencies to the audio recording, which can make the high frequencies of the entire mix or the track of a specific instrument / vocals more distinguishable and "transparent."
Skeptics (or, let’s be honest, people who will always think things were better in the old days) criticize plugins. They insist that plugins are unable to repeat the chaotic harmonic distortions of real tape recorders. They claim that algorithms do things that are too "correct" with the sound signal, while tape recorders acted on sound in an unpredictable, "magical" way, which is the whole point.
Look, perhaps in some grander sense, the skeptics are right. You might not ever be able to capture the magic of chaos and unpredictability with an algorithm. But even accepting they might have a point, it’s not really applicable to the modern, practical tasks of music production. So let's work with what we have, and what we have is even quality and completely free tape machine emulators.
You can start getting acquainted with virtual tape saturation of sound with an excellent plugin called Chow Tape Model, which has greatly impressed the music community in recent years.
The plugin was created by Jatin Chowdhury while he was studying at Stanford University. A musician, programmer, and now, founder of his own company, Chowdhury DSP, Chowdhury completed the initial version of the plugin in 2019. Afterwards, he published a scientific article "Physical modeling of analog tape machines in real time."
Initially, Chow Tape Model emulated a high-quality stereo tape recorder Sony TC-260 released in 1967. Several more models have since been added.
The plugin sounds amazing on the drum bus, guitar, master bus - practically everywhere. Playing with its settings, you can understand and hear in real time those pleasant (and not so pleasant) tape distortions we talked about earlier.
The main thing to remember here is that the changes that virtual tape machines bring to the sound are just spices for your musical dish. And like real spices, they should be used carefully and in moderation. Excessiveness in dealing with them leads not to the improvement of the mix, but to its degradation.
