true but would the choice of the fader being log or linear become part of the equation. So with digital boards do we have log or linear fader and is there a way to determine this by the manufacturer.

I think this was the big question/thought of mine.

If fader 1 is at -20dB and fader 2 is at -10dB and DCA is at 0dB

If a DCA fader controls the FADER (relative to its current position) rather than absolute dB then when moving the DCA -5dB results in fader 1 at -30dB and fader 2 is at -15dB.

I think we've sufficiently debunked/proved that most consoles' DCA/VCA change the dB for each controlled fader by the same difference in the DCA.

-----

I am curious mathematically if there are any differences between lowering summed inputs or lowering a summed output.

Fader A,B,C

D = reduction

DCA} A*D + B*D + C*D =

or

Group} (A+B+C)*D =

Mathematically there isn't a difference?

Are my formulas even correct?

---

I think I'll try this out by adding signals on a sound board and see what the output differences are.