Audio Summation: Part 3 In An Ongoing Series On Essential FundamentalsCombine two equal level sources: Do we get +3 dB or +6 dB? The correct answer is yes. And there are even more possible outcomes as well.By Bob McCarthy • Posted in Reading Room on August 7, 2018Welcome to the third part of a series of articles exploring the principles and properties of audio systems and related fields. This time we focus on the properties of audio summation. Perhaps you know everything on this subject already, but just maybe there are a few holes that can be filled in and make the reading effort worthwhile.
Question: Combine two equal level sources: Do we get +3 dB or +6 dB?The correct answer is yes. And there are even more possible outcomes as well. There’s a lot of confusion on this subject in the pro audio community so let’s set the record straight.
Summation results depend on two critical ingredients: relative amplitude and relative phase. If the two signals are matched in level and phase then we get a doubling (2x, i.e., + 6 dB). This seems pretty straightforward, and yet there are readers out there that are thinking “I heard it was +3 dB.” So if these are both right, then what is the differentiator?
Correlation. In order for the summation result to be consistent over time (which we call a “steady state” value), the signals must be correlated. They must be the same song with a constant relative amplitude and phase relationship. This could be steady state addition (up to +6 dB) or cancellation (down to – 60 dB or so).
Continue reading on PSW:
https://www.prosoundweb.com/channels/live-sound/audio-summation-part-3-in-an-ongoing-series-on-essential-fundamentals/
Author
Topic: Audio Summation: Part 3 In An Ongoing Series On Essential Fundamentals (Read 1333 times)