Peak Levels when using K-System

Robert Katz Leave a Comment

From: Richard

Bob,

How’s it going? Hey, I have a quick question for you regarding PEAK levels at K14 or K12. I’m getting pretty good at shooting right between the two, almost like a K13 (I’m using Klanghelms VU meter aligned to -13 mostly). This seems to me like a good compromise between a musical sound and the fact that one way or the other I will have to limit or hard-clip a client reference to about -9 on the VU meter to sound in the ballpark (until it goes to mastering of course).

One thing that I’m noticing though is that the highest peaks on kicks and snares sooner or later do hit over 0dbFS. I tried to go a little lower (arriving at K14) and it still is there. The only remedy is to put a limiter on the drumbus and take off a db or two.

What gives? Shouldn’t I be able to run K14 and not run into overs? Do you see that issue? Do I have excessive transients that I should be more careful about?

Hi Richard,

Depends on your goals. Of course if you are working in 32 bit floating point, then for the time being the question is academic. If you are trying to make a nice mix, then it’s not too much of a problem because you can give the floating point file to the mastering engineer and he should be smart enough to know what to do with them. However, you may not like what he does with those peaks! It will change the sound of what you are hearing. Remember that your DAC is clipping if your file is going over, even though the file is 32 bit float, so you are hearing the “bad” results of those transient peaks clipping. If it’s strictly occasional percussion peaks the clipping may sound benign. It is only when you have to meet the real world, specifically, conversion to AAC, that the overs have serious meaning in this narrow case of occasional “innocent” percussion peaks going over.

However, if you are trying to make a finished master, then good fixed point behavior is your goal. And with very clean material that has not been peak limited sometimes percussion peaks can occur that are higher than 14 dB above the 0 point. And if you decide to peak limit it to get a higher RMS you may or may not like the sound of the result!

Inspect the true peak with a true peak meter. If it goes over zero, really if it goes over -1 dBFS, then you should be worried about AAC conversion or bad behavior by DACs, SRCs and other systems. At that point you have to make a wise decision as to whether you should reduce your overall level (which would be the nicest thing) or add a peak limiter to soften the true peaks (which can easily degrade your sonic quality, by losing transients and somewhat reducing the soundstage depth and imaging). That’s your tradeoff if you are making a master at this level with very little peak processing.
Hope this helps,

Bob

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