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On a paper from AUDIO ENGINEERING SOCIETY (italian section)(paper GTC010),I read about the setting of loudspeaker to mix for theatrical, to align a -32dbfs to make corrspond to 85 db SPL, but everywhere here on internet in many threads i read -20 dbfs to 85 db spl, can anyone clarify this point? what is the right setting of my loudspeaker to start any mix

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The most common standards are -20 and -18, there are some people who use -22 though. It's an issue of how much head room you want while you're mixing. You can mix to whatever reference you like, just know that it will affect your mix decisions. For example, if you mix to a -22 reference your mix will likely be quieter than if you mixed it at a -18 reference.

Setting your digital/electrical reference level to match a specific SPL is also partially dictated by the volume (meaning size...you know, length X width x height) of the room you're mixing in:

Greater than 20,000 cubic feet (566 cubic meters) - 85dB-SPL
10,000 to 19,000 cubic feet (283 to 565 cubic meters) - 82dB-SPL
5,000 to 9,999 cubic feet (142 to 282 cubic meters) - 80dB-SPL
1,500 to 4,999 cubic feet (42 to 141 cubic meters) - 78dB-SPL
Less than 1,499 cubic feet (41 or less cubic meters) - 76dB-SPL
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  • Sorry to be a pedant here but calibratin topics can often lead people astray with ambiguities. Shaun, you mention peak at -20 or -18 being standards but don't you mean the level of rms pink should meter there, as opposed to peak metered pink noise? – Brent_in_Sydney Jan 30 '13 at 22:11
  • @Brent_in_Sydney - no. anytime you're talking about calibrating to a standard (either monitors to dB-SPL, or electronic trims to voltage), you're talking about peak levels...not RMS. – Shaun Farley Jan 30 '13 at 22:16
  • But as I understand it, pink noise doesn't have a peak value, it flexes over time hence all the discussion of correlated vs decorrelated, so convention is to always discuss pink in rms values: meyersound.com/pdf/cinema_technical_papers/… – Brent_in_Sydney Jan 30 '13 at 23:15
  • @Brent_in_Sydney - Doh! You're correct on the pink noise point. Thanks for the fact checking! – Shaun Farley Jan 31 '13 at 0:03
  • No stress, I don't mean to be an ass - it's just that room calibration is a topic near and dear to my heart :)) – Brent_in_Sydney Jan 31 '13 at 3:40
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In a normal theatrical environment/stage it should be either -18dBFS = 85dBSPL or -20dBFS = 85dBSPL (I believe -20 is the commonly-accepted standard now). For TV its the same but to 79dBSPL. I'm curious where the 32 comes from. That's a very oddball number unless There's something I'm missing entirely.

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-20 dB Full Scale is the commonly accepted standard.

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  • that's ITU reference level, yes? – georgi Jan 30 '13 at 18:48
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I believe I located the paper you were referring to (in Italian):

http://www.atic-ntc.org/Notizie/Gestione%20del%20Suono%20nella%20Produzione%20Audio%20per%20la%20Cinematografia.pdf

Section in question:

Osservazione: Dopo aver studiato il problema e misurato rumori reali in ambienti dal vero, e quindi indicativi delle esigenze di dinamica di un film, si è rilevato che è consigliabile fissare una corrispondenza tra un rumore rosa a 85 dB SPL (pesato C) nel punto di ripresa, limitato in banda (20 Hz, 20 KHz), e un livello RMS digitale equivalente a quello fatto segnare da una sinusoide a -32 dB FS di picco. I parametri di allineamento qui riportati sono da considerarsi validi non solo per la presa diretta ma anche per la registrazione di musica, effetti e doppiaggio. Sarà poi in fase di mixage che tale dinamica, realistica, sarà adeguata agli standard di consegna del prodotto. Tale indicazione di massima può ritenersi un utile punto di riferimento, che favorirà ampia dinamica e lavorazioni di postproduzione omogenee e agevoli dal montaggio al mix. L'audio cinematografico non e’ neppure in grado di riprodurre realisticamente picchi quali quelli prodotti da un semplice battimano, che presenta appunto picchi di 30 dB superiori a quelli del dialogo, richiedendo almeno 20 dB di headroom in piu’.

I was able to get a rough online translation:

...it was noted that it was advisable to attach a correspondence between a pink noise at 85 dB SPL (weighed (C) at the point of resumption, limited in bandwidth (20 Hz, 20 KHz), and a RMS level digital equivalent to that reported by a sinusoid to -32dB FS peak...

I also have never heard of -32 dBFS as a reference level - in the US we almost exclusively use -20 and EU almost exclusively -18. I woud be interested to understand more from this paper and see what the author's basis is. If someone could translate that would be great. Thanks.

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  • it mention an equivalent rms of 32 dbfs peak to peak so it is not a 32 but 32/1,41 = 22 dbfs i think – alidav Jan 30 '13 at 16:05
  • -32 / 1.41 = -22, and with the fact that your average VU meter is off by 4db, you get -18dBFS at 85 dB SPL? And then you look at the size of your room and lower to 79 or even 73? – georgi Jan 30 '13 at 18:45
  • oh, and the sinusoid, not all rms meters read the same if you change that to a more complex wave... – georgi Jan 30 '13 at 18:46
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thats the document, it mention 32 dbfs peak to peak not rms.

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