Loudness and the available dynamic range
Every composition has a maximum peak. Most often this peak is a tutti chord. A smaller ensemble, for example a chamber orchestra, reaches the maximum loudness with less instruments then a large orchestra. A quartor has a complete other loudness structure then a chamber ensemble or a large philharmonic orchestra. But, no matter how large or small the ensemble is, one thing have all incommon, respectively stays the same, this is the total available dynamic range on the final media.
Calibrating the maximum peak with a "ff tutti chord"
The idea of the ff tutti chord calibration is based on the fact, that you the composer, knows most often in advance where the loudest point is in a composition, and therefor you can set the needed headroom in advance.
The maximum peak in a recording session in a concert hall, is only in so far different, that the recording engineer can check the required headroom during rehearsal, and adjust the recording level and having enough headroom, so it doesn't clip when he records a final master.
A "ff tutti calibration chord" for a classical period composition could be as follow:
1 Piccolo note
2 Flute notes
1 Oboe note
1 Englishhorn note
1 Clarinet in Bb note
1 Bass Clarinet note
1 Bassoon note
1 Contrabassoon note
1 Trumpet note
1 Horn note
1 Pianoforte chord
1 Timpani note
1 Gran Cassa note
1 Piatti note
1 Vln I note
1 Vln II note
1 Vlc note
1 Vlc note
1 CB note
Now play back the full chord with ff samples with as many notes per instrument you think it will have at the end, and all at velocity 127, this will produce the signal with the maximum peak level. This signal you use to calibrate your VI or Kontakt track fadersto an uniform level, for example the suggested -6 dB, or more if the stereo master still clips.
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