Adding Decibel in Digital Audio

[Angelo Clematide]

Adding two digital audio signals, the resulting level will depend on whether the signals are the same or different.

a) If they are the same you will get +6dB. If they are different you will get circa +3dB.

b) If one signal is a modified version of the other, in this case they are neither the same nor completely different.

c) Another case would be were the second signal is simply the first one out of phase. In this case the sum is zero and you get: 0dB + 0dB = minus infinit dB.

.

For example adding a single channel pink noise 0dBFS Peak, -13.0dB RMS avg, the resulting level increase is:

2 channels
[-6.02dB] + [-6.02dB] = 0 dBFS

3 channels
[-9.54dB] + [-9.54dB] + [-9.54dB] = 0 dBFS

4 channels
[-12.04dB] + [-12.04dB] + [-12.04dB] + [-12.04dB] = 0 dBFS

5 channels
[-13.98dB] + [-13.98dB] + [-13.98dB] + [-13.98dB] + [-13.98dB] = 0dBFS

.

[Justus]

@Angelo Clematide said:

a) If they are the same you will get +6dB. If they are different you will get circa +3dB.
.

I once learned that an addition of signals with the same level results in a peak of +3dB.

Best regards,
Justus

[Angelo Clematide]

@Angelo Clematide said:

a) If they are the same you will get +6dB. If they are different you will get circa +3dB.

Erratum:

a) If the two signals are identical, the increase in level when mixed together will be +6dB at any point in amplitude.

.

[mathis]

@Angelo Clematide said:

a) If they are the same you will get +6dB. If they are different you will get circa +3dB.

Erratum:

a) If the two signals are identical, the increase in level when mixed together will be +6dB at any point in amplitude.

.

In electronics: 6 dB in Voltage
In acoustics: 3 dB in Power

[Dietz]

Famous prorec.com primer articles here ->

[URL=http://www.prorec.com/prorec/articles.nsf/b97f38ca2751fda58625680900056bad/ea68a9018c905afb8625675400514576?OpenDocument]Part 1[/URL]

[URL=http://www.prorec.com/prorec/articles.nsf/b97f38ca2751fda58625680900056bad/ea68a9018c905afb8625675400514576?OpenDocument]Part 2[/URL]