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Zero

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luis Markson:
On Master L/R output meters, is 0 always +4dBu?

Elsewhere is the signal path, DSP for example, 0 is 0dBu (.775 Volts).

Why are these Zeros indicating different voltages?

Ivan Beaver:

--- Quote from: luis Markson on April 13, 2011, 07:02:50 am ---On Master L/R output meters, is 0 always +4dBu?

Elsewhere is the signal path, DSP for example, 0 is 0dBu (.775 Volts).

Why are these Zeros indicating different voltages?

--- End quote ---
Actually there are more differences than that.  0dBu, 0dBV and a number of DSP's have their outputs "calibrated" so that they are reading how much level the output is before you reach the threshold of the limiter.

 So it doesn't give any real indication of actual output level-unless you know the threshold of the limiter-and even then-it might be before the output gain-which could change the level even more.

You really need to know what the particular gear you are working with is calibrated to.

It is not that one is wrong-but there are different ways of looking at the same thing.

Such as with weightings on an SPL meter.  Your ears say it is a certain loudness-but the meter can read very different depending on whether is on A or C weighting-fast or slow response etc.

None of those change how loud it is, but do give you a different way of analizing the actual incoming signal.

RYAN LOUDMUSIC JENKINS:

--- Quote from: luis Markson on April 13, 2011, 07:02:50 am ---On Master L/R output meters, is 0 always +4dBu?

Elsewhere is the signal path, DSP for example, 0 is 0dBu (.775 Volts).

Why are these Zeros indicating different voltages?

--- End quote ---

On Mackie mixers 0 = 0dBu not +4dBU.

John Roberts {JR}:
0VU=+4dBu is a carryover from old school 600 ohm termination standard of 0VU=+4dBm  (dBu is same voltage as dBm was when terminated by 600 ohms).

As others have mentioned there are even more 0VU standards popular in other industries or market segments.

Rather than confuse the issue by listing even more 0VU standards, just figure out what your gear is doing and adjust accordingly. Most line level in/ line level out gear, will not mind a couple dB one way or the other.
=====

Now for something that could be confusing, the most different metering approach is found on some modern digital gear that displays level as XdB below full scale or clipping. So for that gear, nominal 0VU or typical operating level will measure something like -18dB or -20dB FS (below full scale).

JR

Brian Ehlers:
Even after you figure out what your console's 0 dB is voltage-wise, there's still the question of its time-based behavior (something Ivan mentioned).  With a musical signal, peaks which meter as 0 dB might actually be hitting much higher.  Tom Young recently posted an excellent article discussing this issue and suggesting a nifty method to determine the true time-based behavior of your meters.

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