I have been reading the article "Keeping Your Headroom"(http://www.soundonsound.com/sos/jun10/articles/pt_0610.htm) in the June 2010 print of SOS and was confused what the author was trying to get at. I went to one of my instructors and he also said that it made no sense. To summarize, the article claims that you could lower the master fader to get rid of its clipping and also the master fader can be used for sub-mixing instead of Aux tracks since Aux tracks clip at lower levels than master faders. In my opinion, why would you mix to reach the point where your master fader is clipping, then to get rid of it by lowering the master fader? Why not just mix so that the master fader isn't clipping in the first place? By doing what the author suggests, aren't you introducing additional calculations to made for the master output? Why not just have one single calculation by keeping the master fader at unity gain Please post your opinion on this subject since I have been taught to keep the master fader at unity gain in order to get a accurate level metering and mix. This article completely contradicts mix procedures that I have been taught.

Quote dragonryu10:

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I have been reading the article "Keeping Your Headroom"(http://www.soundonsound.com/sos/jun10/articles/pt_0610.htm) in the June 2010 print of SOS and was confused what the author was trying to get at. I went to one of my instructors and he also said that it made no sense. To summarize, the article claims that you could lower the master fader to get rid of its clipping and also the master fader can be used for sub-mixing instead of Aux tracks since Aux tracks clip at lower levels than master faders. In my opinion, why would you mix to reach the point where your master fader is clipping, then to get rid of it by lowering the master fader? Why not just mix so that the master fader isn't clipping in the first place? By doing what the author suggests, aren't you introducing additional calculations to made for the master output? Why not just have one single calculation by keeping the master fader at unity gain Please post your opinion on this subject since I have been taught to keep the master fader at unity gain in order to get a accurate level metering and mix. This article completely contradicts mix procedures that I have been taught.

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thats as may be but my experience is that when doing a lot of real life mixs you do just end up sometimes overloading the master channel.
Levels just creep up

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Matt
www.krcollective.org

Yes, in an ideal world you would leave the master fader at unity gain and leave enough headroom on your aux busses that there is no need to add extra master faders. But in the real world it doesn't always work like that. If you have lots of tracks with volume automation and so on, it's easier to lower the level of a single master fader than to trim all of them when you encounter clipping.

Quote dragonryu10:

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I went to one of my instructors and he also said that it made no sense.

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He might want to read it again. Mike Thorton has forgotten more about Pro Tools than most people know, and reading it through myself just now to refresh my memory, his arguments seem clear to me.

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To summarize, the article claims that you could lower the master fader to get rid of its clipping

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Yes. The point is that the output from PT is only 24 bits wide, while the internal mix bus is 48 bits (or 32bit FP in PTLE), and they are configured to provide greater headroom than the output.

So even if the mix gets so hot that it overloads the output the chances are the mix bus itself is still clean. By lowering the master fader you are attenuating the output from the mix bus before routing it to the output. Consequently, it is possible to recover the apparently overloaded mix.

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...and also the master fader can be used for sub-mixing instead of Aux tracks since Aux tracks clip at lower levels than master faders.

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Correct -- although the reason is thte fact that the signals passed from the aux mix to the master mix have to be in 24 bit format -- that's where the headroom is lost, rather than the aux mix bus itself.

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In my opinion, why would you mix to reach the point where your master fader is clipping, then to get rid of it by lowering the master fader?

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In a perfect world you wouldn't. If you leave a sensible headroom margin when tracking then the full mix shouldn't overload the outputs -- just as it doesn't on an analogue mix.

But, lots of people still track very hot in the misguided belief that you have to peak digital recordings close to 0dBFS, and the more tracks you try to mix togethaer the hotter the output will be of course.

All Mike is saying is that if you find yourself in the situation where the mix appears to be getting too hot for the output, pulling the master fader back a bit will cure the problem.

It might not be 'ideal practice' but it is a valid solution to a common problem.

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Why not just mix so that the master fader isn't clipping in the first place?

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Good idea... but not everyone has such a diligent approach, and sometimes things conspire to make that not work out as intended.

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By doing what the author suggests, aren't you introducing additional calculations to made for the master output?

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No. Those calculations have to be done anyway. The output of the mix bus has to be multiplied by a valkue representing the master fader position. It makes no difference whether that position is unity or -12dB -- the sum still has to be done.

You could argue that the multiplication could result in an unnecessary runding error and redithering... but in pracice its going to happen anyway, so it makes no pracical difference.

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I have been taught to keep the master fader at unity gain in order to get a accurate level metering and mix.

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The position of the master fader doesn't affect the accuracy of the metering. The metering tells you what the output signal level is; the master fader controls the output level.

And if you're always going to keep the master fader at unity you might as well not have it there at all. However, the designers put it there for a reason....

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This article completely contradicts mix procedures that I have been taught.

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Not every tutor knows everything and there are usually several ways of working, each with different advantages and diadvantages and each suited to different situations.

Ideally, you should soak up the opinions and advice of everyone, analyse why they advocate a particular way of working, understand the pros and cons of that advice, and then apply it in the appropriate situation.

hugh

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Technical Editor, Sound On Sound

I just wanted to add that I had always been afraid of the whole headroom scenario. I was continually fighting with trying to get that bloody master fader to read without it tipping just into the red at key points in songs.... and can you belive the Bass player in my band... he said "Can you not just bring back that fader so it doesn't do that?"... I looked over in dismay and said "Yes I can... but that is not the point!"

Turns out it was the point, after pushing back the master fader to like -2db the mix didnt clip and I had no red light. The other fact was that I couldn't hear any difference at all...my Bass player was actually right for a change

I think the one thing I learn from this forum everytime I read posts from all the experts is that you just gotta use the two things on the side of your head. I mean obviously you do not want to clip your tracks...but surely if you are listening and have a decent set of headphones/speakers.. you can hear things are either right or wrong. Also Dragonryu10 (I guess a street fighter II fan?) try this technique as I find it very useful.

On your channels insert a gain/trim plugin (on Reaper I use one of the JS plugins Unity Gain). I then keep the fader at 0db but I will adjust the levels via the plugin and knock off like -12db and suddenly I have lots of headroom and can work on mixing. If you find you have to push up the fader miles... then increase the gain on the channel... if you have to bring it too far down then reduce the gain on the plugin even more. I found this technique very useful when I recorded a song which had pretty much everything peaking at -2/-3, I learned from that

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There is nothing Grim about this Reaper
We Fell From The Sky

Happy Birthday Henry-S

Andy

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When the going gets weird, the Weird turn Pro.

I've never understood master fader fear. Pretty sure it comes from the old old ProTools days when PT had bad maths and it was pretty common practice not to touch faders or change volume when necessary, especially on the master fader, for fear of introducing bad mojo, but it seems to persist.

There is no problem adjusting the master fader to keep your mix under control - it does no bad things to your audio, and it's a damn sight quicker than going back and readjusting all your individual levels and all automation.

The master channel has a fader for a reason. Most DAWs these days internally have *tons* of headroom above the conventional "0dBFS" fixed point that will be marked on the meters. You can drive well into channel "clipping" (it isn't clipping) but as long as those levels come down before the main output you'll be fine.

Thank you for all the reply postings. It cleared things up and now I think I understand what the article was trying to point out. I guess not all engineers have the same working habits and some times a different approach can be the answer to a major headache. As a student I'm trying to soak up as much knowledge as I can and I'm really glad that I made this post

One 'hidden' factor with the fixed point PT HD mixer is that when the signal is passed to and from the mixer itself it is going from 24bit to 48bit and back again. Hugh mentioned this but let me give a practical example. Say you have your drums bussed to an auxiliary on bus1-2, and a limiter on that aux. The drums might be quite high in level as they tend to get tracked quite hot and then get compressed and eq'd etc. There's always that tendency to lift the kick and snare even further during the mix. Now the bus is 48bit and it's not going to clip, but what can easily happen is that clipping occurs at the point at which the bus passes the signal back to the aux. At that point the signal needs to squeeze back through the narrower 24bit bottleneck. So we get reds on the aux? Well not always. If the aux is metering post fader and we're limiting it, we may never see that red. So the way to deal with this is to create a master fader set to bus 1-2. That master fader controls the actual level returning from the bus. It also crucially meters it. So you can see whether you're really clipping or not, and you can trim the bus slightly if so. So why not just put the limiter on the master fader? Because master faders are not included in delay compensation. You only need to bother with this on a return where you're summing a lot of high level signals.

J

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www.jackruston.com

Excellent example and description Jack -- thanks.

hugh

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Technical Editor, Sound On Sound

Thanks for the example Jack. It goes to show that, if you are using Protools, you still need to know about its inner workings if you want to get the best out of it. Quite a bit of mythology about digital audio has been created because people didn't understand Protools' inner workings properly and they assume that the issues with Protools apply to all digital audio.

To someone brought up with analogue technology Protools' internal resolutions make some kind of sense, but people brought up with 64 bit floating point and delay compensation everywhere will find it harder to get to grips with.

James.

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JRP Music - Audio Mastering and Restoration.
http://www.jrpmusic.net

Hi folks,

I am glad this article has caused all this discussion and thanks to Hugh and Jack for explaining it more clearly.

I wrote this article because it seemed counter intuitive and a hidden issue. I agree best practice is to not hit the red light on the master fader but remember some folk don't even have a master fader in their session so they have no way of telling except the devices bolted to the sides of their heads!

If you get to the point where the mix is hitting the red light on the master then you have two choices, pull each of the channel faders down a bit and risk upsetting the mix or pull the master fader down a bit. I wanted to show that pulling the master fader wasn't a cheat. It was absolutely fine to do it this way.

Also I sometimes have hit the problem where my sub groups have hit headroom and so to find a way to help that problem by using a master fader on the sub group aux was a very useful solution.

Thanks again for the conversations.

Mike.

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Mike Thornton
www.osd-uk.com

Thanks Mike

hugh

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Technical Editor, Sound On Sound

Quote Mike Thornton:

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If you get to the point where the mix is hitting the red light on the master then you have two choices, pull each of the channel faders down a bit and risk upsetting the mix or pull the master fader down a bit. I wanted to show that pulling the master fader wasn't a cheat. It was absolutely fine to do it this way.

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And equally, is it okay if you find too much headroom left in your mix just to pull up the master fader at the end? (My DAW is Harrison Mixbus)

Can't remember where I read this -- either in an SOS article or on the infamous digital vs analogue 'headroom' thread on Gearslutz -- but is it true that if you leave lots of headroom on each track when recording, then plugins such as compressors will respond better (in a more 'analogue' way) to the signal? Especially those plugins that model analogue circuitry?

So following that idea, would it be best err on the side of caution when mixing (as well as recording) and then at the last minute bring up the master fader?

Yes -- better to err on the side of caution and remove the unwanted headroom at the end by pulling the master fader.

hugh

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Technical Editor, Sound On Sound

Quote Hugh Robjohns:

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Yes -- better to err on the side of caution and remove the unwanted headroom at the end by pulling the master fader.

hugh

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Were you trained on old BBC consoles? I've been PUSHING faders to increase level for quite a few years now :-)

BTW - while we're mostly talking about PT here, anyone working an older version of Logic should go looking for a good metering plug-in. For now, I'm running an old G5 with Logic 7, and very often the meters won't show clips, when tracks are actually clipping. Running a meter plug like Inspector (or whatever Roger Nichols calls it now) will show 'overs' occurring, sometimes of up to 20 samples worth, while Logic's metering still shows amber, but no reds. Not good !

Hopefully later versions of Logic are more accurate, but sometimes the bits on the sides of our head won't pick up clips, and if you're pushing the levels and your meters don't show them either, then it can cause trouble- especially if you're 'mastering' (on the cheap, like a lot of us, at home) for commercial use of any kind.

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http://anotherfineday.bandcamp.com/ http://anotherfineday.co.uk http://apollomusic.co.uk

Yes you can to a point, but I was talking specifically about the way the Pro Tools mixer is configured and works under the hood. On a general point, dynamic range (the difference between the headroom {maximum signal} and the noise floor {minimum signal}) is a two way street. The further away you go from the headroom (to leave plenty of 'breathing space') the closer you get to the noise floor. As to plug-ins responding in a more analog way, that sounds very suspect to me. But getting back to your point the answer is yes err on the side of safety but not too far.

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Mike Thornton
www.osd-uk.com

Quote tomafd:

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BTW - while we're mostly talking about PT here, anyone working an older version of Logic should go looking for a good metering plug-in. For now, I'm running an old G5 with Logic 7, and very often the meters won't show clips, when tracks are actually clipping. Running a meter plug like Inspector (or whatever Roger Nichols calls it now) will show 'overs' occurring, sometimes of up to 20 samples worth, while Logic's metering still shows amber, but no reds. Not good !

Hopefully later versions of Logic are more accurate, but sometimes the bits on the sides of our head won't pick up clips, and if you're pushing the levels and your meters don't show them either, then it can cause trouble- especially if you're 'mastering' (on the cheap, like a lot of us, at home) for commercial use of any kind.

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I also recently found this free plugin, which looks even simpler than Inspector:

http://www.solid-state-logic.com/music/X-ISM/index.asp

Quote Myles Eastwood:

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And equally, is it okay if you find too much headroom left in your mix just to pull up the master fader at the end? (My DAW is Harrison Mixbus)

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MixBus is basically Ardour (with some custom plugs and skinning) which is floating point right the way through, so yea, push it up if needed, no issue.

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So following that idea, would it be best err on the side of caution when mixing (as well as recording) and then at the last minute bring up the master fader?

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Whatever works really, the DAW won't care, but staying within the range of the meters is usually convenient, and if there are plugins with inherent clipping limits (as anything trying to accurately model analogue must have) then they are likely to be better behaved.

Regards, Dan.

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Audiophiles use phono leads because they are unbalanced people!

Quote Mike Thornton:

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On a general point, dynamic range (the difference between the headroom {maximum signal} and the noise floor {minimum signal}) is a two way street. The further away you go from the headroom (to leave plenty of 'breathing space') the closer you get to the noise floor.

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Most software keeps the noise floor well away from any signal. Even with Protools' 24 bit bottlenecks, 20dB of headroom isn't going to be a problem at all. Is this fear of headroom another hangover from the old days of Protools?

James.

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JRP Music - Audio Mastering and Restoration.
http://www.jrpmusic.net

No its a hangover from the old old days of analog and since then also having to spend time bringing the level up of poorly recorded 16 bit recordings and then having to de-noise them! I agree that there is so much more dynamic range in our 24 bit systems with either 32 bit or 48 bit mixers but I would still argue that we shouldn't be complacent about level architecture and we should manage signal levels throughout the audio chain whether it be in the analog or digital domain.

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Mike Thornton
www.osd-uk.com

Yup. We've got a load more range than we used to have, and it's no longer a juggling act between overload and falling into the noise. But there still IS a noise floor, and we need to be aware of it.

Levels in DAWs seem to somewhat obscured.
In analog mixers its the first priority.
Logic studio and its infant sibling Garage Band don't prioritise levels or leveling.
The computer presents a idealised channel strip and signal process for say a'female voice'.
This all turns up to enhance a unknown mike and possible indifferent acoustic.
The mike can be processed to sound like other microphones (a U47!!!)
Samples and loops are offered to copy to tracks.
Guitars can be emulated and revoiced.
IMHO this is the wrong way round.
The live project should open as simply as possible, allowing level and audio monitoring and then processing can be applied to remedy or enhance.
Computer software is obsessed with solutions to all your problems in one programme, too many useless applications which hinder the overview of the recording process.
Back to basics of modulation,levels , dynamics, editing and THEN enhancement ,remodeling, looping, and sampleing please.
It is fab that the computer can organise, process and emulate but it it should not bloat and present a false work flow.

Roger.

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I am the Walrus.

Quote tomafd:

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BTW - while we're mostly talking about PT here, anyone working an older version of Logic should go looking for a good metering plug-in. For now, I'm running an old G5 with Logic 7, and very often the meters won't show clips, when tracks are actually clipping. Running a meter plug like Inspector (or whatever Roger Nichols calls it now) will show 'overs' occurring, sometimes of up to 20 samples worth, while Logic's metering still shows amber, but no reds. Not good !

Hopefully later versions of Logic are more accurate, but sometimes the bits on the sides of our head won't pick up clips, and if you're pushing the levels and your meters don't show them either, then it can cause trouble- especially if you're 'mastering' (on the cheap, like a lot of us, at home) for commercial use of any kind.

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it's worth knowing that it is possible to re-colour the metering in logic.... it;s a bit of a fiddle, and not "supported" but it is do-able .... find the graphics files for the meters, and edit them.......


i did this some time back to give a lower red line.... and greater range of colours up the rest of the meter , so i could see levels more clearly from further away.... (during a period of solo performing & recording)

Quote ROLO46:

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Logic studio and its infant sibling Garage Band don't prioritise levels or leveling.
The computer presents a idealised channel strip and signal process for say a'female voice'.

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Are you saying that when you open Logic, eq (and other effects?) are pre-applied to audio channels?

I think the meter colouring is the key to making setting senible levels as intuitive as possible.

Analogue meters didn't show the headroom margin, digital ones do, and we're stuck with that. So we need a colour scheme that reintroduces the idea of headroom margins and 'nominal operating levels'.

I strongly recomend that the metering used for trackingnad mixing should show green up to -20dBFS, yellow from -20 to -10dBFS and red for the rest.

This approach encourages the user to keep the bulk of the signal in the transition region between the green and yellow sections, with only occasional incursions up into the red bit. The end result is a well modulated signal with a sensible headroom margin.

Hugh

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Technical Editor, Sound On Sound

Not pre applied but offered.

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I am the Walrus.

Quote Hugh Robjohns:

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I think the meter colouring is the key to making setting senible levels as intuitive as possible.

Analogue meters didn't show the headroom margin, digital ones do, and we're stuck with that. So we need a colour scheme that reintroduces the idea of headroom margins and 'nominal operating levels'.

I strongly recomend that the metering used for trackingnad mixing should show green up to -20dBFS, yellow from -20 to -10dBFS and red for the rest.

This approach encourages the user to keep the bulk of the signal in the transition region between the green and yellow sections, with only occasional incursions up into the red bit. The end result is a well modulated signal with a sensible headroom margin.

Hugh

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I wish that were true Hugh.

I have changed all my students' metering, both in terms of colours and behaviour, and I still have to reign them in as they go for the red irrespective of what I set. So, now I start the red a long way down.......

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Samplecraze
Stretch That Note

Quote ROLO46:

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Not pre applied but offered.

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Well, that's all right then! Would you rather they WEREN'T offered?

I think the point that needs to be constantly hammered in is that you can't do anything about levels in the input strip of a DAW. Once the data gets that far, it's too late. Level must be optimised at the front end of the ADC.

For those of us who know what we're trying to achieve, Hugh's suggestion would be a useful visual cue, but I have a feeling it would be the visual equivalent of the ‘ASBO’ for many, where getting meters into the red would be a badge of honour.

It is almost a tradition of working with young bands where I have to explain why I’m ‘under-recording’ everything – at least some red and amber would mean I don’t have to have that conversation every time!

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An Eagle for an Emperor, A Kestrel for a Knave.

Quote The Elf:

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For those of us who know what we're trying to achieve...

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Yes. Silly me. I keep forgetting that sound engineers aren't engineers any more, and most have no interest in the engineering behind what theya re trying to do!

hugh

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Technical Editor, Sound On Sound