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A little something about gain-staging, for those who don't know

Discussion in 'F.O.H.' started by AudioPhile777, Sep 7, 2010.

  1. drew_drummer

    drew_drummer Dancefap

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    I'd need someone clever like JBroll to pop in and give his thoughts, but the more I think about it... the more I think a 64-bit floating point mix engine makes this all null and void.

    I'm using Reaper for this test. But...

    Put a sine-tone on a track. Say it equates to 0db, give it +24db increase on the tracks gain control.
    Now on the master, give it -24db decrease on the gain control.
    Render this out as a mono wav.
    Add it to a new track. Reset the master volume and reset the first tracks volume. Invert the phase of the 'rendered' sine tone.

    Now what I'm getting here is a peak when the file starts, then complete cancellation. Which seems to indicate that even though the track was at +24db and was clipping awfully... the master track being reduced prevented any clipping in the final output file. NOTE: You don't hear any clipping whilst it plays back either.

    What does this mean in regards to the issue at hand? I'm not so sure. But it's interesting and might be relevant at some point.
     
  2. xFkx

    xFkx gain induction

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    Hey drew

    What you are saying is indeed correct, but I think it's just bad practice, especialy when you want to work with analogue equipment or do live shows on non-digital consoles (maybe on digital mixers too, i don't know how the summing engine tolerates levels on the new generation of digital consoles)
     
  3. gabriel g.

    gabriel g. Member

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    as long as you dont clip your ad converter everything is good.
    the reason behind lowering the volume is to have enough headroom for sound changes.
    I for myself lower every channel post fader to -10dbfs so my master bus never clips...

    if you try to get every channel to -3dbfs for example your master bus will clip and thats a bad thing because you wont want the plugins on it cliped also you will export the session in a much lower quality were clipping IS a problem
     
  4. gabriel g.

    gabriel g. Member

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    it would be wo cool if the daw meters would show dbu or vu instead of dbfs and only the mastering fader shows dbfs.
    so no body would go crazy with the levels
     
  5. drew_drummer

    drew_drummer Dancefap

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    IIRC, Propellerheads' Record has switchable metering. Shame it sucks so much.
     
  6. Ermz

    Ermz ¯\(°_o)/¯

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    We'll get a compromise soon.

    Slate's VCC will have a VU meter you can calibrate yourself to whatever level you'd like, and have it correspond to the overload characteristics of whatever console you've got it emulating. Not the same as having a VU meter at the top of every channel in mixer view, but as close as we'll get for now.
     
  7. AudioGeekZine

    AudioGeekZine arsehole know-it-all

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    REAPER and SONAR have custom metering options.
     
  8. dfer

    dfer Member

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    Can someone clarify that?



    Say you track your DI's at -18dBFS and then send it out to the analog domain to a clean preamp for unity gain/boost levels and then on to the reamp box?


    Basically, Would it be good practice to compensate the volume difference in the analog domain just before the reamp box?
     
  9. Force666

    Force666 Member

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    Drew, it would actually make it the same thing. It's not about the DAW it's about the preamps and converters. They are optimized (in theory) to run at 0dbVU, obviously some sound "better" when driver harder. And a 64bit mix engine would make it even less important to drive it into the DAW hot, becuase you would have more headroom.


    0dbVU = somewhere around -20 to -14dbFS (you have to look up your interface/converter spec sheet to find out which exactly).

    Remember guys it's about average, not about peaking.

    It makes even less sense to track hotter and then pull down all the faders for headroom to mix. I find when even using these cautious tracking levels i'm still pulling down faders for mix headroom once you start stacking up 20-30 tracks.
     
  10. colonel kurtz

    colonel kurtz Member

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    blah blah blah

    i don't really understand why people still debate this shit...to me, it's a pretty damned simple concept, and one that was taught to me before i ever plugged in a mic or touched a knob - and that was to keep the peaks of the material being recorded around 0dbvu on your analog meters when tracking. regardless of what that equates to in the digital world with any specific DAW or converter, you're always going to have better fidelity by not pushing your front end too hard.

    sure, sometimes it's fun to push your preamps into the red when tracking to get a little grit into the source...but 95% of the time, just aim for 0 on the preamp, and the rest sorts itself out later!
     
  11. AudioGeekZine

    AudioGeekZine arsehole know-it-all

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  12. drew_drummer

    drew_drummer Dancefap

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    Why are you being a prick? If you're gonna get involved in the discussion, play nicely.

    Let me be clear. My peaks never approach clipping the preamp. I've gotten into the habit of making sure that I peak around -8db (I made a mistake during an earlier post, which I've just corrected)

    I've tried making sure that I peaked lower in the past. It never seemed to make any difference to the mix. Except for the signal to noise ratio. Running the preamp at a lower gain level, and boost internally made the noise more apparent.

    After I record all the material and before I bother to add any effects. I turn all my channel faders down to -11db. This brings my -8db peaks down to -19db. Then when I start adding effects... the peaks will slowly creep up to about -17db.

    What I find in this situation is after the mix is done... each track has increased by a minor amount of decibels and the mix is pretty much an even spread - all I need to do at this point is make minor adjustments. And I end up with a decent amount of headroom on the master channel.

    Now... that may be the *wrong* way to work in you guys' eyes. But it's the result of years of trial and error. I'm happy to learn and improve my mixes further.

    But it's not as simple as you make out.

    My assertion is.... as long as you don't clip your preamps, once it is in the digital realm... it is just numbers, and can be made to work. I do not agree that you should hit each plugin with -18db/0dbVU in order to get the best gain structure.

    At first I was agreeing. But I was tired, and was being a spastic. But the bit-depth of modern day DAW's is so large that you really don't need to worry about hitting each plugin with the same level. Just worry that your final output doesn't clip.
     
  13. drew_drummer

    drew_drummer Dancefap

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    http://www.massivemastering.com/blog/index_files/Proper_Audio_Recording_Levels.php

    This is a good article on the subject. He sums it up as:

    I think essentially what I've been doing is peaking at -8db, and using the mixers gain fader to add in the extra mix headroom. Whether this is right or wrong I guess is a matter of preference. But I learnt the lesson of not peaking at -1db .. maybe I just need to be a lot more hardcore with my peaks. It's possible and I'm completely open to the notion.
     
  14. AHChris

    AHChris Member

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    That was indeed very interesting... This post sums it up very good i think:

     
  15. colonel kurtz

    colonel kurtz Member

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    didn't mean to be a dick

    it's just that this is a topic i've seen beaten to death multiple times, all over the internet, and i dunno why so many people don't understand that they need to just pay no mind to digital meters when tracking...keep the analog end outta the red, and then on mixdown, keep the tracks in your DAW from clipping. such a simple concept(at least to me), but with so many countless hours spent debating it...
     
  16. Klosure

    Klosure Member

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    I think I agree..


    The amount of absolute bollox thats discussed on forums about crap that makes fuck all difference is absurd.

    Ok yes keep out the red on the output and input and quite frankly your fine, I mean on poor convertors there might be a tiny insignificant change but it wont effect the end result.

    Sound on Sound (UK mag I am sure you all read) did a review of convertors and found that the only thing would be a slight change in the sound they impart due to characteristics (ie slightly warmer Apogee convertors) but they all handle things in a similar way - we can hear a difference but this is not to do with the convertors. I wonder if pushing the input is just picking up more of these characteristics.
    Ultimatly it does not effect you enough to care.

    But I digress, we spend a lot of out time talking about this stuff and the Noobies out there begin to believe (as I used to) that this is the shit that makes a difference.

    Give a pro a dictaphone and he could make a better recording than a noobie with 10 grands worth of kit and all the fucking headroom he will ever need.


    My view with digital is stay out of danger (red)and push it a much as you fucking want. If you record everything in brickwalled at 0db thats your mess and probably you need better hearing!

    These are confusing discussions at the best of times because it appears like there might be some truth to it but I am becoming more convinced that noone around here designs convertors!

    I only bring stuff in now around -10db cause it makes life easier.
     
  17. FloridaRolf

    FloridaRolf W.A.T.

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    I think I (sort of) get it now.
     
  18. Mjespo125

    Mjespo125 Member

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    good read, and sorry to bump and old thread but quick question: would this mean that I should be adjusting the gain for "quieter" say vocal parts to get them to peak at -18, then when a louder vocal part needs to be recorded, readjusting the levels in order to get the peaks to stay at -18 by turning down my preamp?
     
  19. TheWinterSnow

    TheWinterSnow Den Mørke Natt

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    The way I would look at it is this: you have a lot of headroom and with vocals they usually get slammed by a compressor which will reduce a lot of volume. So track to where the average volume peaks around -18 to -12 or so just as long as your loudest peak doesn't clip. As long as you don't clip everything is ok, and since the compressor will hit things harder, the end result if you did track a bit hot would be the fact that you wouldn't be using so much makeup gain on the compressor.
     
  20. jimwilbourne

    jimwilbourne I try.

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    yeah. I'm gonna go ahead and ask if I'm missing anything in summery of this one.
    I felt like I understood gain staging until this thread popped back up.
    so basically:

    step 1: track relatively hot at the preamp, but make sure meters don't clip at the preamp.
    step 2: don't push faders too hot. leave lots of headroom. no peaking.
    step 3: make sure each fader's gain does not exceed their buss's gain.
    step 4: make sure each buss doesn't clip.
    step 5: make sure each buss doesn't exceed the master buss
    step 6: make sure master buss doesn't clip
    step 7: leave a generous amount of headroom for the master buss

    without getting into any specific numbers, is this correct?
     

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