# About stems, headroom and mixing?



## EwigWanderer (Jun 19, 2011)

I'm about to start writing score for Dr.Professor's Thesis of Evil movie. At this point I'm not sure will I have to master the score myself or will it be done in proper way by some professional mixer (I hope so!).

Soundmix will be in 5.1, but I can only mix for stereo=(

What are the key things to remember? 
Stems? Is it enough to be different stems for strings, brasses, woodwinds, percussions, solo instruments and electronics. Or should they be divided for low strings, high strings etc?

Headroom? What is a good amount of it? This must be a stupid question, but is the headroom same for loud action cue and small quiet underscore type? 

What else should I take under concentration?

Thank you very much!


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## wst3 (Jun 19, 2011)

EwigWanderer @ Sun Jun 19 said:


> I'm about to start writing score for Dr.Professor's Thesis of Evil movie. At this point I'm not sure will I have to master the score myself or will it be done in proper way by some professional mixer (I hope so!).


Cool! And wonderful for you. You will learn so much from working with a different mixer...



EwigWanderer said:


> Stems? Is it enough to be different stems for strings, brasses, woodwinds, percussions, solo instruments and electronics. Or should they be divided for low strings, high strings etc?


I think it depends on what you want to get as a final result and what the person mixing the project wants/expects. I've heard folks do amazing things with nothing more than the four basic stems, but if it were me mixing I'd want a stem for any element you wanted to be able to control.

Maybe the strings in your score are a small element, and thus always treated the same. Maybe the brass has many highlights, and thus you want independent control over each section. etc etc etc<G>! Create the stems as if you were going to do the final mix, and then ask for additional requirements.



EwigWanderer said:


> Headroom? What is a good amount of it? This must be a stupid question, but is the headroom same for loud action cue and small quiet underscore type?


You want as much headroom as you can afford. That depends, a lot, on the format you are delivering. I'd say 18 dB is inadequate, but it has become quite popular as a benchmark. I shoot for 22dB or even 26dB on really dynamic material. Headroom is not just for dynamic range, but also needs to accommodate the crest factor of the individual notes.



EwigWanderer said:


> What else should I take under concentration?


I think you've hit the big two, but I'd also minimize the use of filters and dynamics processors. You may need to tweak within a stem, but don't process the stems themselves so that the mixer has maximum flexibility from the get-go.

If you want/need effects place them into their own individual stems as well. Reverb and delay processors are impossible, or nearly so, to undo.

Good luck with this, it sounds like an exciting project!


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## Markus S (Jun 20, 2011)

The more division the better for the mixer. Often a subdivision of hight strings low strings etc. is adopted. If you have an easy way to export, best is to export all "instruments".

A safe headroom is less 6 db.

Don't apply any effects, reverb, compression or anything that can't be reverted to the stems, if you are handing them to a professional mixer, except of course if they are part of the "sound design".

Good luck with the gig and good "wandern".


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## wst3 (Jun 20, 2011)

Markus S @ Mon Jun 20 said:


> A safe headroom is less 6 db.



Can you explain, there might be a language issue here (the pro-audio community is notoriously bad at managing language), but 6 dB of headroom seems far too little if headroom is defined with respect to the nominal operating level. If it is defined with respect to the maximum operating level, well, then it really makes no sense.

I'm not trying to be troublesome here (it comes naturally!), just trying to understand, and perhaps learn something.

Thanks!


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## Ashermusic (Jun 20, 2011)

wst3 @ Mon Jun 20 said:


> Markus S @ Mon Jun 20 said:
> 
> 
> > A safe headroom is less 6 db.
> ...



He means -6dB when he says less, and that is plenty for a mastering engineer to work with.


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## maraskandi (Jun 20, 2011)

Hi guys, hope you don't mind me chiming in; 

I feel there are some potentially intricate variables that cloud the term "Headroom". 
We want to have music with optimum dynamic range, and which doesn't overload any of our signal path, whether analogue or digital, along the way. So we need to balance these factors.


Hmmm..
Like Asher says I presume the same, that Markus is referring to stems not peaking above -6db in the DAW output meters so there is room for the mastering. 

But Wst3, are you saying that the use of the term "headroom" in this thread needs to be defined in more detail, in accordance with the laws of physics as they relate to audio?


Relating this to Ewigs initial question about headroom:

My current impression is that if your monitors (incl room acoustics) and metering are properly calibrated it makes for an improved capacity to properly judge a mix from the point of view of it's average and its peak loudness, so ensuring that it has desireable dynamic range, in other words... That you will be able to consistently judge, by ear, the appropriate levels for things, without approaching a maximum that overloads your system.

According to a chap who understands all this intricately:
"When monitor gain is calibrated so an average SPL is 83dB, and you then mix by the loudness of the monitor, then the music will never overload and you will never have to look at a level meter" (B. Katz, 2007)

In other words if you really want to know the answer to the question about headroom, you can either wing it and use your metering, but not rely so much on your ears, or just rely on your ears and not your metering, or you can calibrate your speakers and your metering and deliver mixed stems that don't peak over -6dB in your final stage and which you had the best possible sound reproduction to properly mix.


Am I on the right track?

I'm gonna keep reading, and testing, I want to understand this better in any case.
:idea: :roll: 


Happy Summer Solstice to you all!


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## wst3 (Jun 20, 2011)

maraskandi @ Mon Jun 20 said:


> But Wst3, are you saying that the use of the term "headroom" in this thread needs to be defined in more detail, in accordance with the laws of physics as they relate to audio?


Yes!

One of the problems with the audio industry, professional and consumer, is that we tend to invent terms when we need them, which is bad, or re-purpose terms when they sound cool.

There are very specific definitions of terms like headroom, dynamic range, crest factor, and so on. But these definitions are seldom used in discussions about audio<G>!

It's late tonight, and I'm in the midst of some other things, but I will post the currently accepted definitions, and my interpretation thereof. In the meantime...



maraskandi @ Mon Jun 20 said:


> My current impression is that if your monitors (incl room acoustics) and metering <snippity>
> According to a chap who understands all this intricately:
> "When monitor gain is calibrated so an average SPL is 83dB, and you then mix by the loudness of the monitor, then the music will never overload and you will never have to look at a level meter" (B. Katz, 2007)



Bob Katz is a very bright guy, and his approach to both metering and monitoring are as good as it gets. Bob understands better than most the interface between the analog and digital domains!

But what Bob is talking about is not easily applied, and in the context of this conversation I think it is perhaps muddying the waters.

What the OP was asking about, at least as far as I can tell, is how much headroom to leave in his stems. This is an EXCELLENT question by the way. And for his purposes it refers only to digital domain, so what he is really asking is how many bits should I leave above my nominal operating level?

More later, I promise...


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## Markus S (Jun 21, 2011)

Hey guys, yes, what I wanted to say is : when leaving 6 db of headroom there is no peak above minus 6db - thanks for clarifying! That is before mastering, of course, after mastering you often go for 0,3 db headroom (no peak above 0,3 db), but I know there are other theories and approaches around. Best answer is probably to check with the person doing the mix.


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## maraskandi (Jul 24, 2011)

I guess this is really very basic stuff, despite the complexities of the physics and terminology.

We are working in the digital domain, our output meters aren't really helping us see if our sound quality is high as they don't show level as in the analogue domain. We are operating with samples, bits, rather than true signal, so in order to prevent digital clipping, aliasing, phase issues and other artifacts that are introduced when manipulating our audio, it is essential to mix with our inputs low (leaving significant headroom). 

Given that we are working at least 24 bit the noisefloor is significantly low enough that it won't cause issues later when elevating gain if we operate at low levels in the DAW. Gain-staging is the way forward and keeping it cool is the rule to ensure the cleanest sound.

As wst3 suggests having adequate headroom on all our tracks from input through gainstaging to final output enables mixes to have the required depth, punch and quality of sound they deserve and guards against the damaging effects of peaks occuring in a scenario with insufficient headroom to accomodate. 

In our DAW we have to monitor and set the pre-faders and trim the levels down to the suggested headroom required so that the final product doesn't accumulate horrible artifacts due to the signal being too hot through the gain-staging we set, am I right? 

Running your recording and mixing at too hot a level in an attempt to increase our loudness actually reduces our dynamic range and trying to negotiate artefacts by filtering/EQing can introduce increased gain, compounding the problems of inadequate headroom (seems counterintuitive that cutting increases peaks, but so it is).

That's why nominally we want to set our headroom adequately, preventing all those destructive peaks in the system.


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## Daniel (Jul 25, 2011)

you can download free plugin like PSP VintageMeter :
http://www.pspaudioware.com/plugins/tools_and_meters/psp_vintagemeter/ (http://www.pspaudioware.com/plugins/too ... tagemeter/)
to control headroom for mixing/mastering purposes. You can calibrate to -6.0 dBFS (for mastering) or -12.0 dBFS for mixing

Best,


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## bryla (Jul 25, 2011)

Why not use your DAW's built-in dBFS meter, since it will show you both peak and RMS.

Isn't such a plug-in only for folks who want to impress clients?


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## EastWest Lurker (Jul 25, 2011)

Logic's meters are small and can be a little hard to see accurately so I frequently use Sonaksis Free G.

http://www.sonalksis.com/freeg.htm


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