Master bus true peaks and LUF values

Getting Stuff Done How do I .... ?
#1

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I’ve been producing a track in the mighty Ardour and been banging my head on a few quirks:

  1. While having the Wavelab loudness meter after the master bus fader, the integrated LUFS value differ from the Ardours internal analyzer by quite a bit. Which one should I trust? Is this about the analyzers picking up signal at different points in the chain?

  2. My limiter is set to -2dB (true peak). Still the true peak is at +1.2dB instead the set -2dB. What am I doing wrong here?

Any tips, comments and especially critique is appreciated :slight_smile: Thank you!

#2

Is your master bus fader set to 0?

#3

Yes, the master bus fader is at 0.

#4

Hi,

that is a strange difference in the two reports. Not only is the exported file louder but the difference in loudness range doesn’t fit at all.

First thing to double check afaics would be to make sure that really only the output of the master bus gets exported to the file system.

#5

Possibly, the integrated analyzer is calculated off the exported file, so I would instead of using a VST on the end of the chain to compare it with, analyze the exported file instead.

Good question, is there a difference if you use a different limiter?

Seablade
#6

Try an external analyzer on the exported file to compare it to the post export report.

A quick test for digital-peak would be sndfile-info path-to-your-exported-file.wav. In your case it would show 0dBFS (since 24bit wav cannot exceed full-scale).

Are you perhaps resampling 48kHz → 44.1kHz when exporting, that can change peaks, although a 3dB increase over the entire production would be highly unlikely. Summing to mono may do it. Are you using a stereo panner with < 100% width?

Looking at the waveform in the report, the signal is clipping.

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EDIT: Could it be that you have enabled Ardour Preferences > Signal Flow > Enable master-bus output gain control In that case there may be an additional gain factor after all plugins:

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#7

First of all, sorry for my late reply. And second, thank you all of you who have tried to help.

  1. After all the problem was the “Enable master-bus output gain control” and the fact that I had +3.2dB gain set to that control. This was not set on purpose. Now that Robin pointed this out, everything is pretty obvious. I set the gain to 0dB and disabled the control. After this the signal values did match the true peak ones set in the limiter.

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  1. After resetting the master-bus gain control the LUFs started to match.

Case closed! Thanks for the help!

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