[LAU] [LAD] First release of jkmeter

Steven Chamberlain steven at pyro.eu.org
Sun Aug 3 12:38:17 EDT 2008

Fons Adriaensen wrote:
> Jkmeter is a horizontal or vertical bargraph level
> meter based on the ideas of mastering guru Bob Katz.
> See <http://www.digido.com/bob-katz/index.php> and
> follow the links on 'level practices'.


I was a little sceptical at first, but having read the article I think 
it's a great idea.  My main concern was the magic number '83 dB(C)', 
which has somewhat vague, historic origin, but also I thought I would go 
deaf at that reference level.

With two speakers, I guess that would be 86 dB(C).  Quite interestingly, 
extrapolating the OSHA noise exposure limits down to that level, a 
person could endure that for up to 16 hours a day without hearing loss. 
  That would make it, effectively, the loudest safe level for someone 
who mixes music all day, and so making the fullest use of the ear's 
comfortable dynamic range.
   (OSHA limits are detailed on http://www.elvex.com/facts07.htm )

As an experiment, I tried calibrating both of my monitor speakers with 
-20 dBFS pink noise to 83 dB(C).  Sound at that volume doesn't feel 
comfortable to me.  Perhaps I misunderstood something?  Maybe I'm just 
over-sensitive to that volume, perhaps because I have neighbours here, 
don't have a house to myself, etc.

Under the K-20 system, it seems the maximum SPL when monitoring with two 
speakers would be a scary 106 dB(C).  Those monitoring levels would 
force engineers to keep loudness down, or risk going deaf otherwise. 
Presumably that would serve the intended purpose of the system, of 
avoiding excessive loudness of recordings, but I think it carries some risk.

I think the K-14 system might be more to my own taste.  I believe it 
keeps the 83 dB(C) reference level, but with peaks up to 100 dB(C) in a 
two-speaker setup.  Sustained exposure for 2 hours even at the maximum 
level should still be safe as per the OSHA limits, but of course that 
level should rarely be reached anyway.

I'd very much like to hear how a K-20, K-14, or K-12 recording compares 
to mainstream pop/rock/metal recordings.  Perhaps the high reference 
level would feel more comfortable with program material that isn't so 
heavily compressed.

I'm also curious to know what sort of monitoring levels other people 
have been using.  I'd estimate that in the past I've been down to 
something like 60 dB as a reference level, and resorting to headphones 
when I felt more scrutiny was needed.  This unfortunately seems 
necessary here because I have other people living around me.

I'm looking forward to trying out the jkmeter implementation.  And I 
imagine a K-14 and even K-12 version would be very useful someday.

Steven Chamberlain
steven at pyro.eu.org

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