File Prep for Mastering...getting headroom

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bannerj
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File Prep for Mastering...getting headroom

Post by bannerj » Thu Jun 28, 2012 12:21 pm

Trying to finish a project I've messed with for six years on and mostly off! With 10-12 mixes per song, I've not done a good job of watching my overall levels.

I've tried it by trimming -10db on each track. It gets tricky with subgroups that have a compressor. But then if i just lower the buss of a group the individual trax are hitting the fx sends hard and I have trim all of them.

Seems like a hassle but I can tell a difference for sure. This has changed the mix, but I know the songs so well now that I can easily get them back into the same ballpark without blistering the meters.

It's kind of a good exercise. Helps me loosen my white knuckled grip on the songs.

Anybody else messed with this and have tips/warnings?

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Post by MoreSpaceEcho » Thu Jun 28, 2012 12:49 pm

no real tips, but headroom is definitely a good thing. so long as there's no clipping, any peak level below 0dbfs is fine to send to mastering, but i really do think ITB mixing sounds way better when you keep the levels on the lower side. whenever i have stuff to mix, i start by pulling all the tracks down enough to leave me tons of headroom on the master fader. like 10db. invariably everything creeps back up, but if you start low you won't paint yourself into a corner where you're fighting for headroom.

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Post by bannerj » Thu Jun 28, 2012 1:00 pm

I trim all my mixes now by 10db or so depending on how it was recorded. This project just became a monster over the years. There is a huge thread on GS that is basically about where unity should be ITB. Kind of a headache of a read, but yeah....everything opens up better if I'm not peaking higher that -6.

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Post by vvv » Thu Jun 28, 2012 2:45 pm

I use -3 as my working peak level, just so I can better see the wave form for edits.

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Post by Nick Sevilla » Thu Jun 28, 2012 4:16 pm

Does it sound good where you had it?

PRINT. DONE.

The mastering guy will do his magic on it regardless of where the printed file is at level wise.

Unless he's a pussy.
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Post by bannerj » Fri Jun 29, 2012 7:05 am

^^^ yes...after working on these files off and on for to many yeas, I was tempted to just go ahead and print them as is. But, I was too curious to see what I might gain by bringing the level down by trimming each track. And it's been a great lesson. Plus, I'm splurging with a more expensive ME and it seems silly to not give him more headroom to work with since I'm paying him more than I've spent on the whole project.

Again...hiring the higher end ME for the sake of the learning curve. In truth, I have three MEs doing the same song on spec. Then I'm going to pick one of them to do the whole thing.

Pretty excited!!

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Post by egr » Fri Jun 29, 2012 7:17 am

Does headroom as you're describing it actually exist in digital files? I mean, once you send the files to the ME, if he needed the audio to peak at a lower level he could just turn it down and re-render (or some similar process) right? This is an honest question, not trying to be snarky or anything. :?:
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Post by Nick Sevilla » Fri Jun 29, 2012 7:21 am

bannerj wrote:^^^ yes...after working on these files off and on for to many yeas, I was tempted to just go ahead and print them as is. But, I was too curious to see what I might gain by bringing the level down by trimming each track. And it's been a great lesson. Plus, I'm splurging with a more expensive ME and it seems silly to not give him more headroom to work with since I'm paying him more than I've spent on the whole project.

Again...hiring the higher end ME for the sake of the learning curve. In truth, I have three MEs doing the same song on spec. Then I'm going to pick one of them to do the whole thing.

Pretty excited!!
Good luck!
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Post by bannerj » Fri Jun 29, 2012 7:58 am

egr wrote:Does headroom as you're describing it actually exist in digital files? I mean, once you send the files to the ME, if he needed the audio to peak at a lower level he could just turn it down and re-render (or some similar process) right? This is an honest question, not trying to be snarky or anything. :?:
From what I've read there is less and less debate about this...it can get heated. The question is largely focused on ITB since gain staging through analog is a different beast with different rules of thumb.

The issue ITB is how the summing buss, the math of it, can bring all your tracks and plugs together. It might be a different rule of thumb if you have moved to a DAW in 64 bit....I don't know.

From my experience I can hear a definite, less pinched...squashed (not in a good way) overall mix if I don't push my summing meter to *peak* (not RMS) any higher than -6 ro so. The discipline requires you to turn up your monitor knob after you trim each track.

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Post by bannerj » Fri Jun 29, 2012 8:14 am

Nick Sevilla wrote:
bannerj wrote:
Good luck!
Thanks! My goal was to make a record I would like to listen to and this is it.

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Post by jhharvest » Fri Jun 29, 2012 8:28 am

egr wrote:Does headroom as you're describing it actually exist in digital files? I mean, once you send the files to the ME, if he needed the audio to peak at a lower level he could just turn it down and re-render (or some similar process) right? This is an honest question, not trying to be snarky or anything. :?:
Yes, sort of.

Let's oversimplify this a bit: Let's assume our digital values go from 0-9. You make a file that has peaks at 9, so this gives you 10 discreet values that they can be. If you "turn it down" (i.e. multiply all values with a number under 1), so that your peaks are now at 5, then you have a reduced dynamic range to play around with. But this will also enable you to, for example, boost frequencies without it clipping. So it's all swings and roundabouts.

However this example of ours has approximately 10 decibels of dynamics at maximum, i.e. not very much. Now in the real world if you have a 24 bit file, the values go from 0 to 16,777,215 rather that 0 to 9. This is a dynamic range of 144 decibels. This means effectively if you turn down a 24 bit file by 20 decibels, you still have more dynamic range to play with than humans can generally hear.

Some people say that lowering the level of a digital audio file reduces the quality. Personally I think it doesn't matter with 24 bit files, unless you repeat the operation many, many times. Try it for yourself. See if you can hear a difference. Try it then again with a 16 bit file, 12 bit file, 8 bit file and a 4 bit file. At some point it will start to make a difference but who records at 4 bits? (As an extra point of interest, try adding weighted dither noise to your 4 bit test files - you might be surprised of the results...)

I did a test recently where I first lowered the amplitude of a 16 bit file by 20 decibels and then amplified it again by 20 decibels, bringing it back to normal. The result was more or less as expected: I ended up with 24 decibels of noise compared to the original file.

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Post by dfuruta » Fri Jun 29, 2012 10:18 am

If you record and mix at lower digital levels, your ADC and DAC certainly might respond better. This is a potential reason that it could sound better to mix with a lower peak value: it might be less taxing on the analog section of the DAC. If you're working with outboard processing, this is something to think about.

But, since most DAWs operate at 32 bit floating point or higher internally, practically speaking there's boundless headroom for processing. There's no reason to mix with a high peak level, and it's easier to paint oneself into a corner doing so, but it's hard to see how it would damage the sound if one stays entirely in the computer.

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Post by Dakota » Fri Jun 29, 2012 10:18 am

Chipping in: yes indeed, 24 bits is lots of headroom and it's not a good habit to be running up in the tip top of that at the track, buss, or master level - overs can be happening that you don't notice directly, and that can add up as a spackly buzz that's just not pleasant to the ears. If you are really wanting to use "all the bits" for resolution: if your highest transient peaks are just reaching -6, you are using all the bits. When mixing to send off to other mastering engineers, I tend to have the highest peaks not more than -6, and when getting in other's mixes to master, I appreciate the same.

A practical thing that comes up: when I get songs to mix that are tracked elsewhere and the individual tracks are recorded really loud, it's trickier to patch insert hardware directly onto that track, as the levels may already be too hot to have room to find the sweet spot for the outboard gear - plus, when the D/A and A/D are way up in their top headroom, the analog stages can't slew fast enough and sound constricted. It's not a big deal, but it's slower to route to auxes with hardware inserts, or to patch in some trim before the hardware, and then you can't A/B as fast. Not a biggie, but it's better if the individual tracks are hanging -12 ish or even -18 ish rather than having peaks going up near zero.

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Post by Jeff White » Fri Jun 29, 2012 12:06 pm

Everyone should be mixing at around -18dB fs to -14dB fs RMS at 24-bits. This way, you have the headroom to work with most peaks that come your way in 24-bit land. You don't need to slam mixes. I have been offering my services as a professional mastering engineer for the past 3 years, and let me tell you, the best-sounding mixes that I receive are the ones where the mixing engineer understands gain staging. I find that without buss compression (I always ask for files without compression on the 2-bus, and at least 3dB of headroom above the highest peaks), the folks who mix without worrying about how loud their tracks will be, who balance the drums and the vocals and and then bring in the rest of the instruments around them, and who get that "shooting for the middle" on the meters is perfect, these mixes end up being the best masters. Why? because with a little mastering compression, EQ, and Peak Limiting, I can get them to a nice level that competes on an iPod but isn't crazy oppressive loud (RMS overdrive).

In 24-bit, you don't have to worry about slamming your shit. Turn up your monitors, dammit!

http://www.digido.com/mixing-tips-and-tricks.html

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Post by fossiltooth » Fri Jun 29, 2012 1:07 pm

When I'm ITB, I tend to have my gain-staging so that my mixes sum around 0VU RMS. (-18dbfs on my system.) This because most plugins are calibrated to receive that kind of level, and it also leaves plenty of headroom to avoid digital overs on very dynamic material.

I tend to mix through a bus comp, which might boost RMS by a dB or two from there, and once the mix is really starting to come together, I'll usually initiate a limiter across the Master Fader set to reduce by a maximum of 1-2 dB and bring the peak output up to -.4 dB.

I guess the old school advice would have been not to do that, but honestly, this is some very light 2 bus processing. I find there are fewer surprises in mastering this way, it makes it even easier to reference against rough mixes and favorite albums, and no mastering engineer has yet to complain about getting a pretty dynamic and great-sounding file that peaks at -.4 dbfs. Of course it's a 24 bit and they can always gain it down entirely transparently before processing further.

No offense meant Jeff, but if an ME asked me to turn off my light bus compressor against my better judgement, I'd probably find another ME. That said, I understand that some people are unduly pummeling their mixes without even realizing it, but that's an entirely different scenario.

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