Re: Question re: levels in digital audio


Subject: Re: Question re: levels in digital audio
From: Jan L. (jan@mostek.se)
Date: Thu Oct 20 2005 - 15:19:41 EDT


If you are working with 24-bit then keeping levels below -12dBFS is
often recommended (and even more, I usually keep everything below
-16dBFS). It sounds better and makes your life easier - what more can
you ask for!

The reason for this is a) You wont lose anything, 24-bit is more than
enough b) You give plugins and mix-bus more headroom.

The talk of distortion if your mix peaks above -6dBFS is based on how
a typical oversampling D/A-converter operates. It will usually
upsample the original signal to a much higher sampling frequency and
interpolate to "fill in the blanks" and in certain instances those
blanks will be up to 6dB above the absolut digital values of the
original signal. This will happen *very* often your signal is
compressed and the normalized to 0dBFS. And this will cause analog
distortion in the majority of D/A-designs as they are not designed to
handle such high levels,

So never normalize to 0dB or even close. To maximize levels you can
use an oversampling meter as is included in the new Sony Oxford
Limiter plugin for Protools. This meter does the interpolation to
give you an exact level indication.

Without such a meter it is best to keep peaks below -6dBFS. If they
say -12dBFS then it may be the common level in the video industry, I
dont know.

Sorry for the broken english - I can explain this much easier in
swedish ;=))

The distortion caused in upsampling D/A:s is described in more detail
at the tllabs.com website (Downloads and then White Papers).

/Jan Larsson

20 okt 2005 kl. 04.26 skrev Phil Thomson:

> Hi all,
>
> I should probably know this, but I have a question about levels in
> digital audio. In my own work, I've always normalized my digital audio
> stuff to 0 dB or similar levels, and have never had any problem with
> distortion or clipping while running my levels at close to 0 dB, but
> lately I've been hearing that -12 dB is the maximum level that you
> should shoot for, because clipping is introduced at even -6 or -8 dB.
> Is this only true of DAT or DV, or is it the case for digital audio
> across the board? I've *never* heard any clipping in my own work (on
> the computer), but the video folks I'm hanging with now claim that -12
> dB is the new 0 dB. What's up?
>
> PT
>
> --
> Phil Thomson, BFA, MFA
> 0101000001101000011010010110110000100000010101000110100001101111011011
> 01011100110110111101101110
> hellomynameisphil@gmail.com
> http://www.sfu.ca/~pthomson/
>



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