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Adding Decibel in Digital Audio
Last post Mon, Sep 04 2006 by Dietz, 5 replies.
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Posted on Sun, Sep 03 2006 13:12
by Angelo Clematide
Joined on Thu, Sep 08 2005, Posts 1139
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.

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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

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Posted on Mon, Sep 04 2006 16:18
by Justus
Joined on Thu, Jun 23 2005, Hamburg, Germany, Posts 41
Angelo Clematide wrote:

a) If they are the same you will get +6dB. If they are different you will get circa +3dB.
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I once learned that an addition of signals with the same level results in a peak of +3dB.

Best regards,
Justus
OPUS 1
Posted on Mon, Sep 04 2006 17:00
by Angelo Clematide
Joined on Thu, Sep 08 2005, Posts 1139
Angelo Clematide wrote:
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.

.
Posted on Mon, Sep 04 2006 18:18
by mathis
Joined on Sat, Feb 07 2004, Munich, Germany, Posts 1137
Angelo Clematide wrote:
Angelo Clematide wrote:
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
Posted on Mon, Sep 04 2006 22:52
by Dietz
Joined on Tue, Aug 06 2002, Vienna / Europe, Posts 7430
/Dietz - Vienna Symphonic Library
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