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Speaker calibration tutorial for students
Old 1st December 2018
  #61
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I'd appreciate some help, I'm clearly missing something here about this speaker calibration process.

I've placed a -20dB pink noise file on a mono track set to unity gain and panned it hard left. On playing it, I was expecting my loudness meter plug-in on the master output to read -20 LUFS. But in fact, the Dolby pink noise file reads -21.0 LUFS, and the Blue Sky file reads -22.2 LUFS. (Don't worry, I'm not playing them at the same time!) It is strange/wrong that not only are they somewhat different from each other, but more importantly, that they don't read -20 LUFS?

Thanks for any input!
Old 2nd December 2018
  #62
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LUFS is not the same as RMS
The files are -20dBFS RMS

On top of that, pink noise files with the same RMS will often have different crest factors which will influence the LUFS measurement.
Old 6th December 2018
  #63
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Thanks!
Old 7th August 2019
  #64
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Pantone's Avatar
 

Browsing the Genelec site they note when level aligning:

Quote:
If the standard recorded level of filtered (500Hz - 2kHz) pink noises is -18 dBFSrms for SMPTE RP200's (-20 dBFSrms for SMPTE) and then the absolute level calibration can be made so that the sound level meter reads a level 2 dB lower than specified for broadband pink noise. This is because there is less energy due to band limiting of the band-pass noise.
I'm interpreting this as, if aligning a small room to 83dBSPL (for example) one should aim to hit 81dBSPL(C) on a slow averaging SPL meter? First time I've seen this adjustment mentioned. In other people's experience is this good advice?
Old 7th August 2019
  #65
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Quote:
Originally Posted by Pantone View Post
Browsing the Genelec site they note when level aligning:



I'm interpreting this as, if aligning a small room to 83dBSPL (for example) one should aim to hit 81dBSPL(C) on a slow averaging SPL meter? First time I've seen this adjustment mentioned. In other people's experience is this good advice?
This means if doing a sub/sat alignment where you use band-limited pink noise for the sat component, measure for 2 dB down because the added effect when you include the sub component (also done with band-limited pink noise but LPF now for the range covered by the sub), there will be an increase to the overall level by +2dB when using non-band-limited (full range) pink noise to check the whole system (sub+sat per channel.)

If you are using full range speakers with full range pink noise, this wouldn't apply to you. You go to the regular level. This only applies when using band-limited pink noise.
Old 7th August 2019
  #66
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Pantone's Avatar
 

Quote:
Originally Posted by pentagon View Post
This means if doing a sub/sat alignment where you use band-limited pink noise for the sat component, measure for 2 dB down because the added effect when you include the sub component (also done with band-limited pink noise but LPF now for the range covered by the sub), there will be an increase to the overall level by +2dB when using non-band-limited (full range) pink noise to check the whole system (sub+sat per channel.)

If you are using full range speakers with full range pink noise, this wouldn't apply to you. You go to the regular level. This only applies when using band-limited pink noise.
That's much clearer now and makes sense, thanks!
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