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dBV-dBu-LUFS and Loudness

Aggiornamento: 6 apr 2020

Soundtrack: 2nd exit - If you wouldn’t mind (2nd exit © 2016) —

Hi guys, welcome again with another episode on my irregular column #fahBlog on my personal website Today i want to talk about Loudness and levels of the audio signal suggested for good and correct results. This topic could be intricate and complicated considering the many urban legends circulating within forums or self-made experts. Unfortunately for those people, Loudness, Dynamic Range , LUFS and other specific terms can make a huge difference in a music composition’s quality and sound. So definitely we need to be aware of them while we are mixing or producing a song. Dynamic Range is the ratio, measured in dB, of the loudest and the quietest audio signal, or sound signal.

As we can imagine, a smash signal compression , reduce this ratio; so it reduces the dynamic range but it helps the loudness perception of the music composition. Therefore a good song needs to find the perfect balance and compromise between Loudness and Dynamic Range.

Anyway, after this short intro, we can go deep in the magic and mysterious world of dB (decibel) First of all, all audio signals , both in analog electronics field, digital audio and acoustics field too, got the same measurement unit, the decibel. One name, several applications, why? The decibel isn’t an absolute unit of measurement but a ratio between two signal (example: signal in and signal out) or two values; furthermore, the decibel isn’t a linear unit of measurement but a logarithmic one because the high range of values that it considers. In the analog electronics field, so referred to the voltage, we can find the dBV, the decibel voltage ratio between 2 signals (in-out) with a reference of 1 volt; or the dBu, the decibel voltage ratio between 2 signals (in-out) with a reference of 0.7746 volt; both of them are used to measure input and output levels for electronic audio equipment.

For the pro audio equipments the standard level of the voltage is +4dBu, differently, for the consumer audio hardwares the standard level of the voltage is-10dBV. Obviously a -10dBV signal is definitely weaker and with a worst signal/noise ratio than a +4dBu signal.

Let me be clear, a -10dBV and +4dBu signals levels are not related to balanced and unbalanced cables; so for the cables we deal with the signal transference, for the -10dBV/ +4dBu signals we deal with voltage levels. In the acoustic field we can find the dBSPL, the ratio between the sound pressure level and its reference of 20 µPa (micro pascal). Last but not least in the digital audio field, we can talk of dBTP , decibel True Peak, the ratio of peak amplitude of a signal with the reference of the maximum peak of the same signal that a device, speaker or whatever can handle without clipping; 0 dBTP is the maximum signal that a processor can handle but in the audio world is strictly suggested stay below -1 dbTP.

Other measurement is the dbFS, decibel Full Scale, the amplitude ratio of a signal with the reference of the maximum peak of the same signal that a device, speaker or whatever can handle without clipping. After years, more or less in the 2011, the broadcast networks introduced a new standard normalization unit. This happened to avoid the consumers’ regulation of the TV volume by remote during advertising or different shows in different channels. The LUFS (loudness unit in reference at full scale), is the unit of measurement to quantify the loudness’ perception of a part of a song or music composition analyzing the average level of the whole composition.

Grossly, the perceived loudness of a song /music composition. So if we have 2 different compositions and both of them got the same LUFS level, the listener will have the same loudness perception. Following the broadcast networks, the music industry started to use the LUFS as normalization standard too. Every music platform and music streaming services have different LUFS level, but mostly Spotify, Apple Music, Tidal or Soundcloud have a standard between -14 LUFS and -16 LUFS range.

In conclusion, based on my experiences, i will give you some small standards to follow in the whole producing workflow process:

*The Recording*: Set always 24 bit to have enough headroom; Record signals between-12dBFS and -6dBFS maximum to have enough headroom to process it;

*The Mix* : keep your final mix (to be mastered) output between -6dBFs / -8dBFs so the master engineer can work on it;

*The Mastering*: a level maximum of -14 LUFS / below-1 dBTP with a Dynamic Range of DR8 - DR12. But above all, i suggest to use your ears to lead a good mix and good production;

Ears are the best weapon of any sound engineers.

All the best, F.

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