[LAU] -3.0 dB

[Fons Adriaensen]

On Mon, Sep 21, 2009 at 06:19:51PM -0700, carmen wrote:

> On Mon Sep 21, 2009 at 06:17:04PM -0700, Norval Watson wrote:
>
> > I have read that it is good practice to aim for a maximum
> > level of -3.0 dB when mixing, mastering, normalizing etc.
> > in the digital domain.
> 
> two mono chans at -3 should sum to 0db, afaik

They could sum to anything between -inf and +3dB,
depending on how related they are.

And even for decorrelated signals, where RMS
of the sum will 3dB higher than each channel
separately, the peak level will increase by
more than 3dB, up to 6dB.

What is the 'correct' level for any recording depends
on the type of music, the context, where and how the
recording is going to be used, etc. 

If you are participating in the loudness war (see
http://en.wikipedia.org/wiki/Loudness_war) you will
try to squueze out the last fraction of a dB. 
Usually with disastrous effect on the quality of
the sound or music, even if it does not clip or
distort.

If you go for a more musically enjoyable result it
depends very much on the type of music. For anything
'heavy' you'd want to maximise the loudness without
clipping. In that case a fast peak limiter at -1dB
or so will do wonders without affecting the sound
too much. 

For anything classical or when you want to preserve
the natural dynamics of real instruments and performers.
peak levels are less of an issue, and your decisions on
level should be based on what your ears tell you, and be
guided by a meter that does indicate both RMS and peak.
Ardour's meters are near to useless for this, jkmeter
will do a good job if you learn to use it.

Ciao,
 
-- 
FA

Io lo dico sempre: l'Italia è troppo stretta e lunga.