Leaving headroom for mastering? Why?

I don't get why one leaves gain headroom for mastering.
I hear it all the time so I know it must be important but..
If I have exported a stereo wave file to master, surely I can simply reduce the gain in one of several ways before adding EQ, Comp. or limiting etc.
What am I missing?

Ah! so the point is not to squash it too much, not that you should keep the master level down a few db before export.

Ive kinda wondered this myself. In the past I have recorded bands and applied nothing on the master fader. At the end, after mixdown, I would normalize it to make it as loud as possible for the client (once again with no extra processing on the master fader). But when I send these files to a mastering engineer they come back and say that they have no room to work and that I need to resend the songs. So I send then the same exact file without the normilazation and everything is ok. If a mastering engineer is just going to chop off the transients with a compressor to bring the overall RMS level up then why can't they work with the pre-normalized file as only the very single top peak of the entire normalized file is hitting the ceiling when I send it to them(and the song will be crushed to the ceiling by the ME anyway. Or why as stated by the OP why can't they just back it down a few DB if they need the room to start crushing? I hope this makes sense.

As a rule I leave -3 to -6 db headroom. However you should consult with the mastering engineer and find out what they want. I had a guy who wanted songs at -.1 (no kidding) so he could master them.

As I understand now, it's more a function of leaving dynamics (minimal compression and limiting)  than levels.
One could over comp and limit on the tracks and do the same damage.
Right?
So it seems we need some guide that indicates acceptable dynamics rather than levels at master.

M_Glenn_M


As I understand now, it's more a function of leaving dynamics (minimal compression and limiting)  than levels.
One could over comp and limit on the tracks and do the same damage.
Right?
So it seems we need some guide that indicates acceptable dynamics rather than levels at master.

Yes.

If you export your mix in 32bit floating point, the mastering engineer can harmlessly adjust the levels by whatever amount is necessary and appropriate before the start of processing and still achieve whatever level is desired at the output.

But if you compress/limit things too much, there's no good way to undo that in mastering. 

Chregg


"*I don't understand why anyone in the modern world would use anything less than a 32bit fp delivered to mastering. " to be fair most people probably do Drew

Really? Well, like I said, I don't understand why. 

But even with 24bit, the only really important difference is you just need to make absolutely sure you aren't clipping when you export...

I think there is much misinformation about mixing an mastering. Don't handicap your mixes by not using your tools. Mixing should be to your ideal conclusion. I use 2bus compression to varying degrees on pretty much everything I do. When I'm done it pretty much sounds like a record that you have to turn up a bit more. The mastered version should sound like what you sent in just a little louder and maybe some more tonal unity across the collection.

I have a few guidelines that I follow that are based on feedback I've gotten from MEs.. No overs, ever but I will go to 0dbfs (but I don't shoot for it). I will manually duck any standout transients that keep the me from pushing the overall program a bit louder with makeup gain on the 2bus comp. All the mastering engineers I use have analog chains so as long as I don't clip their DA then it's not a big deal for them to do whatever they need to do in the analog domain. 

bandso

Lanceindastudio


DON'T normalize before mastering. Give them 3-6db of room to work with. DON'T limit or compress on the master buss. No need to discuss  further. End of discussion. 


Lance

As I asked in my post. Why? Why can't they just turn it down 3-6 db if they need additional headroom.  I only have one peak hitting the -0.1 ceiling and the song is not clipping anywhere but that one small peak. What is the scientific/sonic difference.  (If the master buss is clean)
 

Aesthetics, attention to detail and professionalism - Its like me asking you to put the frosting on a piece of cake before you deliver the cake instead of handing me the tube of frosting to apply myself. It is nicer for me not to have to do an extra step. I like my mastering engineer as happy as possible when I turn in a mix.

Sound wise, if you are not limiting, peaking etc. you are not going to have any sound issues if they just turn down the main for you.
Normalizing - I just dont like to go there JUST IN CASE it might be messing with the mix.

Lance

Normalizing boosts the entire clip/song louder until the single loudest peak reaches the normalize setting. As long as this is below 0 then there should be no clipping.

There is more to mastering than compression and limiting. Many are forgetting here what the first stage usually is and that is EQ. This is one main reason why you should leave 3 to 6 dB of headroom in your mix. 

So supposing we need to boost our mids are whatever by 3 or 4 dB. When this is applied the level of the track goes up. If the track is already sitting close to 0dB FS (And still has dynamics) there is no where for the EQ to boost into (if boosting is required of course) so clipping results. It means the level has to be pulled down before the EQ in order for any boosting to take place. This is OK but if the track has that headroom built in it is just one less thing to do to the signal before any mastering begins.

Each stage can add a few dB here and there. EQ might increase the overall rms level of a track by say 3 dB. If the compressor following is averaging about 3 dB of gain reduction then a further 3 dB can be added there in the make up gain. Now our track is already 4 or 5 dB louder before the limiter even kicks in and then that can do the final raising of rms level.

If 3 to 6 dB of headroom is allowed for right at the start then all these processes flow rather well and all work nicely. So if you are going to send out any tracks to a ME then take the advice and do not apply any processing on your mix and allow for 3 to 6 dB headroom as suggested here is good advice. Stop trying to make the track loud. That is NOT your job. Turn your mix up loud in the room if you want to hear it loud. That is your job.

This looks overly complicated guys.
 
Making good sounding music should be simpler than this.
 
Cheers,
 
Jhon

filtersweep


I think a problem with normalization is that in raising levels uniformly across the entire freq spectrum it can, depending on how much freq range there is in the material, alter the listeners perception of the music. The mid range loudness is most affected because the ear is much more sensitive to dB changes in the mid range.

That is not how normalization works. It is not uniform but proportional. All the levels are raised proportionally to the highest that has been set to a higher level. The dynamics do not change.  Also it has nothing to do with frequency but level only. 

bandso


Thank you Jeff, yes eqing and other processes do affect DB's being raised and lowered.
ok my question has been sort of side stepped so I'm most likely going to bail on this one, as I can't seem to convey what I intended. I hope the OP gets the answers he is looking for. All I've heard is don't do it, with no sonic/scientific reason on why I can't give a louder (normalized to 0.1) non damaged/compressed audio file to my clients and then just have the ME bump it down a few DB's before he/she starts their magic.
Peace!

I really don't think there is a holistically scientific reason for it in existence, but that's ok. Music and Mixing/Mastering is art, right? Ask a Mixing or Mastering engineer whose done lots of work for a major label and they'll nearly all tell you that the label gets what they want, regardless if you feel right about it or not. Science doesn't enter into their minds at all, and they pay the big paychecks. Sure, the music sucks on many levels, but the reality is this: If you want your music to sound "good" take these recommendations above and give it a go. If you want your mixes smashed like a major label would ask for, then do that. I think your judgment will kick in, and you'll know when something isn't right, or you wouldn't be interested in doing this sort of thing. That's the fun part. 

The only wrong answer is not doing what the customer asks for. I think a clipping limiter on the Main buss is fine, if it means that a single kick drum hit if, when normalizing, the rest of your mix becomes a whisper (NOTE: I don't Normalize, myself, either). In that case, I recommend putting that clip limiter on a separate buss for your kick or automate that single transient by hand like the old days. -0.1 is perfectly fine if there's a few transients that get there and no audible side-effects (Know your DAW). You just don't want your guitars, bass, keys, or vocals to be hitting -0.1, even on occasion. I have some mixes that come out in the red, mainly because if I turn down all the faders even by 1db, the mix isn't right for my ears. Luckily, the floating-point 32-bit (or 64-bit) will work for me because I keep it 32-bit when I go to my Mastering Engineer. He uses Wavelab, which takes it in and works the magic I want and there's no audible clipping. He recommends not going into the red, but never has he told me to give him more headroom, although I'm sure he would love it.

There's rules of thumb, but nearly every situation is different. Use some good recommendations to start, then, after you've had some successful Masters generated, use your experience. It's a tweak-able rulebook, but everyone works a little differently, even Mastering Engineers.  

Hope this helps!  

John is correct and you are incorrect filtersweep. Think of it as this. If the highest peak is say 5db from 0dB FS then every sample point over the entire waveform is raised by 5dB during normalisation. Simple as that. There will be no change in the sound of the wave at the end of the day, only the fact that it is now 5dB louder than it was before.

Normalisation does not just effect peaks as you may be thinking. It effects every single sample in the waveform. 

Maybe in the past though if you had a very quiet recording (in 16 bit) and normalisation was applied then the digital noise is going to be boosted up as well. But these days with 24 bit being the norm and converters being much better then it is not much of an issue.

And to bandso who asks why cannot a waveform be knocked down a few db before the EQ so the ME can do his magic. Well some experts say that  adding and subtracting gain to a waveform could be seen as altering the quality but only to a slight extent. If this is happening in the 64 bit world then a lot of precision can be maintained during this process so it is Ok to do it. But if you were calculating gain changes in a much lower bit depth eg 16 bit then errors could creep in. But I agree this is not a biggie as even on a 32 bit system you are still 8 bits ahead of a 24 bit waveform anyway. And if you were using say the LP64 EQ and used the input trim control to do this then it would be OK even on a 32 bit system as it can be put into double precision mode on mode DAW's anyway. 

This may be something that has hung on from a previous era where it was better to leave well alone. Similar to recording as close to 0dB FS as you can but these days things are much better in terms of the resolutions that are going on behind the scenes so it is not such an issue any more.