Topic: Matrix Source Percentages?

[skotdee]

Quick matrix question: I notice a lot of folks have them labeled with the percentage of each source, ie: 40%Aud/60%SBD

My question is how do people calculate exact percentages? I'm using either Vegas, Audition, or wavelab to synch the two sources, but all I can find are controls to adjust the volume of each source, but nothing on exact percentages. Am I missing something?

Are these just estimates?

[SmokinJoe]

In my case, they are estimates.  For instance... you pull them both up in an editor, and one source is running a little hotter than the other... so you guess it's 60-40.

If you really wanted to figure it out Source A%/Source B%....
60/40 = 1.5
20xlog(1.5) = 3.52dB, so a 60/40 source would have one source 3.52 dB louder than the other.

I remain skeptical that most people do this math.

[skotdee]

whoa, lost me on that math. 20xlog?  Looks like I'll stick to estimating...

[Roving Sign]

whoa, lost me on that math. 20xlog?  Looks like I'll stick to estimating...

Pretty sure that was sarcasm...

Use your ears - mix to taste...no magic formulas here.

[JasonSobel]

whoa, lost me on that math. 20xlog?  Looks like I'll stick to estimating...

Pretty sure that was sarcasm...

Use your ears - mix to taste...no magic formulas here.

no sarcasm here, Joe was just doing the math, based on the definition of the dB scale.
(though perhaps there was some confusion with the "x"  "20xlog(1.5)" just means "20 times the log of 1.5".
 
L_dB = 20 x log(A₁/A₀)

in this case, A₁ and A₀ represent the amplitude of the two wav files.  the Amplitude is a measure of how loud the sound is.  So if you want a ratio of 60%/40%, the source that makes up 60% of the end result needs to be 1.5 times louder than the other source.  that's just simple division.  But to convert that to the decibal scale, you use the equation referenced above, and, as Joe calculated, the result is that source 1 needs to be 3.52dB louder than source 2 for a 60/40 mix.  And, as a check, this makes logical sense in relation to what we'd expect, because a 6dB increase in volume means that the sound is twice as loud (and that's actually 6.02dB, if you do the math ).  that's fairly common knowledge (or should be around here).  And now we know that a 3.52dB increase in volume represents a factor of 1.5x increase in volume.

edit to add:
I agree with Joe, I remain skeptical that most people do the math.  as Roving Sign says, just mix it until it sounds good to you

[Brian Skalinder]

FWIW, I don't do percentages.  I mix til it sounds good to my ears, but I do still capture notes on the mix.  Each of the master source tracks - unedited - represents a baseline.  For my mix notes, I simply note the dB level of each track in the mix relative to its baseline:  track 1 = -6 dB, track 2 = -4, etc.

[tgakidis]

If i put down a % mix, it is pure estimate.  When Joe starts talkin' numbers I get a glazed look on my face and think about donuts....

Seriously though, for me it is just a estimate based on the recorded db's of each source and the mixed db's of the final product.  It is mostly for my own info if i ever want to go back and remaster.