Pre/Post Masking, its effect on a Limiter in a master chain

Discussion in 'Mastering' started by headchem, Dec 18, 2005.

  1. headchem

    headchem Guest

    I've been learning about pre-masking and post-masking lately, and I can't figure out how these pyschoacoustic phenominon affect limiting in the mastering chain.

    This is from the Wave Arts Final Plug manual:
    After researching pre and post masking, I understand the concept just fine. What confuses me is why you'd want 1.5 ms of loud distortion to mask the quieter material preceding it. Or is this "rapid gain ducking" a cause of distortion itself? Is that different from the 1.5 ms of distortion caused by a loud peak?
     
  2. Michael Fossenkemper

    Michael Fossenkemper Distinguished past mastering moderator Well-Known Member

    I personaly think this number is greater. but yes, masking and the way the ear hears things is related to the attack and the release. Adjusting these to a certain amount can reduce the apparent effect of limiting.
     
  3. headchem

    headchem Guest

    Yeah, according to some of the websites I've read, the pre-masking effect can last up to 20 ms, while the post-masking effect can last up to 200 ms. Based on all this, what kind of basic settings should a Limiter be set to?
     
  4. Michael Fossenkemper

    Michael Fossenkemper Distinguished past mastering moderator Well-Known Member

    completely dependent on the material. You have to tune your ears to this. At first it's not apparent but you'll begin to notice it and then effectively adjust for it. Once you hear it, you'll be able to disquise it better but it'll still be there.
     
  5. RemyRAD

    RemyRAD Guest

    The first thing you want to do is understand why you would want a "look ahead limiter"? Certainly a handy thing to have if you absolutely want to prevent peaks from getting by your maximum 0dbfs, 100% level. Generally, I have never really liked the sound of look ahead limiters as they certainly take most of the snap out of the mix. They're more applicable to broadcast purposes and transmitter over modulation, which is against FCC laws and perhaps terrible sounding digital clipping which comes from bad engineering and you have complete control over that. I would not even imagine that Michael uses such a limiter in his mastering? Perhaps? If you want your mix so that it reaches 100%, use your normalization feature in your software, after you're done mixing. Then you take it to Michael who will further enhance the "apparent loudness" level in his mastering procedures. If you want something to "apparently" sound louder, you use faster release times in your compression/limiting, after your mix. Sometimes referred to as "mastering", or at least part of that process. Too fast a release time with your limiter and it will sound like crap because the limiting is then modulating with the sound source. That's not pretty. That's only loud. It's all a trade-off. You have heard radio stations that you can only listen to for a few minutes, even if you like the music? There you go. Can you say " listener fatigue"?

    The whole reason for look at limiting is so that the limiting occurs simultaneously with the peak and not afterwords when the peak has already occurred (even the FCC allows peaks of certain duration and frequency above specified maximums). Can you say " totally squashed, lifeless sound"? At least compromise is not a four letter word.

    Your original mix sounds great! Now go pay Michael some $ and sit in with Michael.

    emy nn avid
    Now without looking at limiting
    Remy Ann David
     
  6. Michael Fossenkemper

    Michael Fossenkemper Distinguished past mastering moderator Well-Known Member

    Remy, I think you win first prize for having "Michael" the most in a single post.

    but in general, you are right. Limiters are probably the smallest equation for me. I use them mostly to shape peaks, in all digital mixes that is. I still get a lot of mixes on tape, as well as the same mixes in a digital format without tape. The nice thing about analog is that it significantly reduces those super peaks, digital mixes don't have that benifit and the use of a limiter to shape some of those super peaks is necessary, if you feel it's needed. But if you address some of these things early in the process, this makes life easier down the road. For instance, using ribbon mics to record spikey things. Tube mics, tube or transformer mic pre's etc... Dynamic mics also work great for warming something up. A lot of recording techniques were designed and refined for the mediums that were used. Now that mediums have changed over the years, the techniques have been slower to adjust. Since tape is not an option for a lot of people, choosing variable non linear devices to capture something is the next best thing to give things a warmer more analog sound which in turn allows you to turn up the volume more without relying on the funky sound of limiters.
     

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