DeWayne Dixon wrote:Digital audio levels are much lower than analog levels for headroom purposes.
+4 dBu = 0VU = −20 dBFS
The professional analog audio standard of +4dBu will measure 0VU on an analog audio console.
The digital audio standard of -20dBFS will measure around -20VU one the same console.
I know this is a way old post, however, this comment is in error. As I found it when I was searching for what the ATEM audio output was referenced to, I want to correct it for anyone else who might come across it in a forum search:
+4dBU and-20dBFS are exactly the same, there is no difference in level or distance to clipping (headroom).
This statement is correct:
"+4 dBu = 0VU = −20 dBFS"
However, these statements are not, and directly contradict the above true statement:
"Digital audio levels are much lower than analog levels for headroom purposes."
"The digital audio standard of -20dBFS will measure around -20VU one the same console"
Lemme 'splain...no, there is too much, lemme sum up (points for reference <g>).
An analog meter reading of 0VU references +4dBu, or 1.228 volts.
A digital meter reading of -20dBFS also references +4dBu, or 1.228 volts.
Max audio level on an analog meter reads +20VU and references +24dBu, or 12.28 volts.
Max audio level on a digital meter reads 0dBFS and also reference +24dBu, or 12.28 volts.
Both of these meters give 20dB of headroom to the point where clipping would occur.
Both of these meters read in dB increments...one is just dB above or below 0VU and the other is dB below full scale, but both result in the exact same voltage output levels from the mixer.
So, feeding a 0VU analog signal into an analog console will read 0VU.
Similarly, feeding a -20dBFS digital signal into an analog console will also read 0VU, not -20VU.
Feeding a 0VU analog signal into a digital console will read -20dBFS.
Similarly, feeding a -20dBFS digital signal into a digital console will also read -20dBFS.
Hope this helps,
Jeff