So in a recent thread there was a lot of discussion about mixing you track close (or not as seems to be the case) to 0db, and it struck me by the answers given that a lot of people completely misundertand the concept of 0db, and in fact "db" by itself in this respect is absolutely meaningless.

We talk about differences in sound levels in decibels.

So one sound can be 10 decibels louder than another. Or you can take a sound signal and make it 10 decibels quieter. Or you can leave your fader at 0 decibels and make absolutely no change at all.

So that is the meaning of 0 dB - no change in level.

You CANNOT say that a sound has a level of 100 dB. You cannot do that.

When you see something like, "The noise coming from the freeway is 100 dB", that is absolutely meaningless and written by someone who has no knowledge of decibels. (They probably mean 100 dB SPL, but that's another topic.)

0 dBFS on the other hand refers to a specific level.

'FS' stands for 'full scale'. 0 dBFS is the level of a signal that is at the maximum level your system can cope with without clipping the tips of the waveform.

in the digital realm that equates to specific ranges depending on bit rate so 24-bit digital audio has a theoretical maximum dynamic range of 144 dB, compared to 96 dB for 16-bit however, current digital audio converter technology is limited to dynamic ranges of ~120 dB because of 'real world' limitations in integrated circuit design.


So how do you use 0dbfs in your studio? You need to calibrate your setup, otherwise it's meaningless and you're not mixing to your full potential (headroom etc.) and each time you could have a different result. Trust me, this has a huge effect on your mixes, both in terms of quality and continuity.


How to Claibrate:

Generally you calibrate -20dBFS pink noise to 83dBSPL per speaker with a meter set to C-curve, slow response. That is monitoring gain 0. The "film" standard. Use a K20 meter if possible. This is know as the K system.

The idea of the K-System is that 0 dB on the averaging meter represents a consistent SPL, which is 83 dB SPL (per speaker). Regardless of whether it's K-14, K-20 or K-12.

Some uses, such as a more typical "pop" levels, you would turn the monitoring gain down to -6 dB, so if you would play back the same -20dBFS pink noise it would now measure 77dBSPL per speaker. Because you still like to hear the same loudness on "forte" passages, you will master a bit louder/less dynamic. Pop music standard. Use a K14 meter (20 - 6 = 14).

For mixing, most set monitoring gain to 0 (K20). Normally I have no overs during mixing and the result is a mix of decent average level.
If I'm in doubt on anything during mixing (can't find right level for a track, difficult eq) I pull down the master fader by 6 to 10 dB and make sure it works at that level. If it works on very low listening levels it will work on higher levels too IME. Monitoring gain stays where it is. When I'm done with the puzzle, I just bring the master fader up to 0 again and I'm back at my reference level.

To get that you'd have to change your monitor gain as you raise or lower the RMS level. If you calibrate your monitor gain, you can start working to a fixed monitor gain of -6 dB through 0 dB chances are you can ignore the meters and never overload the peak level! Just go for the sound from that point on. And have more consistent-sounding product. That's the virtue of the calibrated monitor.

I'm not saying that you should not monitor your project at different levels while working - just that returning to and knowing where the calibrated position is, gives you an "anchor" and also keeps you out of Fletcher Munson-errorland.

Why 83db? Not going in to that now but If you're doing highly compressed music it will get fairly fatiguing. For the wide range dynamic music, 83 dB on forte works well in a room with midfield to farfield monitors as the average level for mezzo forte passages will be lower. So you make your adjustments depending on loudspeaker distance, the amount of fatiguing compression you are using and your own personal tastes. At least you will have a calibrated level you can work with. When making your own deviation from the standard, I suggest you listen to a bunch of the dynamic recordings on the honor roll at digido.com to see where they fall on your modified scale and that you have a frame of reference.

The original 85 dB at 0 VU with pink noise and analog media was proposed by Ioan Allen of Dolby many years ago. Ioan says it was a fortuitous accident and not intentional. But yes, it turns out that Fletcher Munson has a lot to do with this level. To put it in other words, it is the level where the ear's response is most flat. So you will get better balanced mixes and masters.

However, audologists warn that 85db is the point at which the ear begins to example the natural damage reflexes caused by high volumes, so IMO it is better to use 83db if not lower, as your standard reference.

Finally, back to the reason for this thread: the reason you want to be close to "0db" is that is the optimum level in a digital system, using all the dynamic range available to you. Going above that results in clipping, but referencing your tracks signifigntly lower will result in inaccuracies in relative levels (i.e. your mix) because of how we hear different frequencies at different perceived loudness levels - in other words, specific things sound different depending on the overall loudness.

I leave you with the link to the white noise for calibrating your system...

http://www.digido.com/media/downloa...o-44.1-wav-file

Please note: not all this is my own work and some was ripped from other sites/forums as they explained it better than I could be bothered to.