[LAU] [LAD] First release of jkmeter

Fons Adriaensen fons at kokkinizita.net
Sun Aug 3 14:29:13 EDT 2008

On Sun, Aug 03, 2008 at 05:38:17PM +0100, Steven Chamberlain wrote:

> Under the K-20 system, it seems the maximum SPL when monitoring with two 
> speakers would be a scary 106 dB(C)

This would happen if you have a sine wave going up to
the maximum peak level. At that point the meter would
indicate +20dB, and be rather reddish. For anything
else the DPM indication is not a good indication of
the real SPL.

The K-20 scale is designed to be used for music that
has a natural dynamic range, e.g. classical or any truly
'unplugged' genre, and that is not or only very lightly
compressed. 0 dB on the meter should correspond to the
loudest parts of the music, and the average level would
be lower, i.e. well below 83 db(C). The 20 dB headroom
above this is for transient peaks that must be reproduced 
without limiting or clipping.
> 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.

The K-14 (and K-12) scales are for music that is more
agressively compressed and limited. If modulated to
average 0 dB on the K-14, that will be acutally sound
somewhat more loud than the uncompressed version using
the K-20 scale.

You seem to make the mistake that using a K-meter you
are supposed to use it as a DPM, trying to get out the
maximum. That is not the case, the idea is that the
loudest parts of you program should indicate around
0 dB on the RMS scale.


Laboratorio di Acustica ed Elettroacustica
Parma, Italia

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