[Ardour-Users] Peak levels on master bus vs single track

[Robin Gareus]

On 03/01/2017 09:47 PM, Alf Haakon Pietruszka Lund wrote:
> I just finished a project in Ardour 4.7.0 on Ubuntu Studio 14.04
> 
> There are several regions in many tracks, some of them overlapping in
> time, most of them not.
> 
> On most of the tracks I used a compressor and a limiter (both from calf)
> to avoid peaks and potential clipping. I set the limiter's output gain
> to minus 2.2 dB.
> 
> As expected, when focused on one of the tracks, the meter doesn't pass
> -2.2 dB.
> 
> However, when focused on the master bus, the meter 'clips' and peaks at
> +0.9 dB.

The signal level of a sum of 2 signals may be higher (up to 6dB in case
of 2 signals) or it may be lower in case some parts cancel each other out.

If you sum two tracks both having the same sine-wave at -6dBFS, the
result (on master) is 0dBFS [1].

You really want a limiter on the master-bus (not on individual tracks)
As far as free software goes, I'd use swh's fast-lookahead-limiter.

ciao,
robin

[1] well, in Ardour's case using mono tracks, the panner will distribute
L/R equal power, the sum will be -3dBFS due to pan-law, bypass the
panner and you'll get +6dB

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