[LAU] -3.0 dB

[Jörn Nettingsmeier]

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
>>
> OK, and thanks for quick reply Carmen...
> 
> In Ardour specifically, I have a stereo master bus with L and R meters each hitting about -3 dB.
> The single numeric display above the meters also reads about -3 dB,  rather than 0 dB.
> Is this what I should be aiming for?

in theory, it's ok to go all the way to full scale (-0dB).
in practice, there are a few problems:

* cheap D/A converters can start to sound nasty even when not overloading.
* it's hard to check for overload at 0dB - you can't ever get louder
than full scale in fixed-point notation, so an overload can only be
deduced by a number of consecutive samples at full scale
* you can have a valid signal with two samples at 0dB, but that implies
that there is an inter-sample peak between those two that is larger than
that. depending on the rest of the signal chain, this can cause problems
(think over-sampling).

for pop productions, -3db is on the conservative side - most people seem
to go for less than -1. for classical, many tonmeisters will not
normalize at all, so that the natural absolute loudnoess is retained (to
some extent) - i.e. you set your volume so that you can just about
endure that wagner orchestra cd, and then you put that lute music on,
and it will peak at -12dB or so... so you don't have to readjust the
volume so much.