Too Conservative Mix Levels?

Recently I received a great question from Mr Knight concerning Mixing levels.  I added his question and my response to our comprehensive FAQ portfolio, but thought that it should also be added to our blog.  Here is Mr Knight's question and my response:

Hi Bob

I'll bet you address this issue quite a bit. I've enjoyed your work on several projects and thought you would be the best person to hear from.

So, I'm in the middle of mixing a project and have some questions about mix levels and initial gain staging. The tracks I have came from several different studios and the levels are all over. So I've done some initial gain adjustments with the trim plug-in on each track just to get everything in the same neighborhood. I initially went for avg around -18dbfs for each individual track monitoring thru the mix bus. I tend to do a lot of low end filtering and other subtractive eq so I thought I'd try that initial staging at -12. I did notice the drum sounds seemed to come to life, but it seemed most everything else was about the same in terms of sound quality. At that starting point I'm still ending up with full mixes peaking at around that same -12 dbfs.Â

I've recently been taking an online course called mixing with 5 plugins to study this guy's methods. It's ok, was hoping for a little more but I've picked up a few things. So I noticed in all the video modules his mix bus is constantly in the red.. clipping. So I made a comment about that as I can't seem to focus on anything else with that going on.

He explained that it's nothing to worry about we can fix that with a gain plug in later. Am I too timid, too conservative? Please set this matter straight. I will rely on your expert opinions with regards to levels so I can get back to mixing.Â

Thank you Bob. Looking forward to your thoughts.

K Knight

Mr. Knight: Thanks for your kind words!

Many so-called "top mixers" break the rules and overload their mix bus, but their material does not necessarily sound better because of it.

However, if their files are going over 0 dBFS, and if they are mixing to a 32 bit float file, and if they are working totally IN THE BOX (inside the DAW), then there is no real overload and the resulting files can be fixed by simple attenuation. I don't recommend overloading the mix bus, it's a bad habit, but technically it is not an overload when you are working in floating point and saving to a floating point file. Perhaps that's what that mix engineer was referring to by saying that a gain plugin could be added later. That is ONLY valid IF they are working in floating point and have saved a floating point file.

But if they overload their mix bus or any previous part of the chain, and if they are capturing to a fixed point (e.g. 24 bit) file, then they have made permanent damage....  Even if they were specifically going for a smashed sound, by the time it makes it to mastering or to a coded format (mp3, AAC) the sound has seriously gone downhill sonically, sounding smaller and less impacting, especially on loudness-normalized streaming services.

Regardless of that advice, purposely overloading a processor or pushing a processor is quite common and an esthetically-satisfying practice; it's done all the time in rock and pop music. Usually not by going over digital level (which sounds harsh very quickly), but by pushing an analog or digital processor to create artistically-satisfying distortion and/or compression. In my pop or rock mixes and also in mastering I often use processors creatively. That's not what you are speaking of, you are just speaking about gain staging without bringing up the processing question.

In your case, as long as your peak levels anywhere in the chain are not going over full scale, it really doesn't matter if your max peak level is -1 dBFS or -12 dBFS. There's plenty of signal to noise ratio in 24 bit recording. And, if you record to a 32 bit float file, then it is totally fixable after the fact by a simple gain boost.

I would say as a guide, If the peak to loudness ratio (PLR) of your mix is above 10 dB (LU), more typically above 12 or even 13-14 dB, then you likely have a candidate for a good mix. The sound is the key of course, the PLR is just a guide. In your case, I advise you work with a loudness meter, try to shoot for no higher than -14 LUFS loudness for a conservative-style mix that is later going to be mastered, and of course no overloads as measured on the true peak which you will also find on the loudness meter. This is just a guide, there may be reasons for you to shoot for a lower PLR, however, once it gets mastered or uploaded to streaming, you may regret having made an aggressive PLR. Always consider the end product. You are not listening to the end product, you are listening to the first stage of a chain that has several steps after it leaves the mix stage. The loudness meter and the PLR will be a guide to helping you get quality mixes, but how they sound is the ultimate guide.

But if you are making a 24 bit file and you worked lower, and your loudness measured, say -20 or even -25 LUFS and your peak never exceeded -6 dBTP, you have made a perfectly acceptable level for a mix. It's probably low compared to many popular music mixes, but technically speaking it will be fine. I go over ALL of this in great detail in my book: Mastering Audio.

Next, when you say that you went for "average" around -18 dBFS for each individual track, what kind of "average" measure are you referring to? I would recommend using a loudness meter, not a peak meter, and in that case if your individual tracks are averaging -18 LUFS on a loudness meter you are certainly in the ballpark of good gain staging. There's plenty of "footroom" in 24 bit audio. Even if your mix averages -30 LUFS loudness it's not going to be audibly harmed, especially if you mix to a floating point file, but it will sound very low unless you have enough room to raise your monitor gain. Or, your mixes can be higher if you wish as long as the total mix peak level does not exceed 0 dBTP.

When you noticed the drum sounds suddenly "came to life" I suspect it was just an illusion of loudness. For example, let's take your  whole mix, listen to it. Then turn up your master fader by 4 dB and simultaneously turn down your monitor control by 4 dB ---- everything will sound the same: the drums would not suddenly "take on more life". Of course if there is a compressor in mix bus (which comes BEFORE your master fader), and you turn up the drums on individual tracks, then you will drive compressor harder with the drums and there will be a different sound. I am simply referring to a perfectly matched linear (unprocessed) gain change with a perfectly matched monitor level change --- everything will still sound identical.

Does that answer your questions?

Best wishes,

Bob