[ardour-users] Exploring Ardour plugin datapaths

[Mark Knecht]

Hi,
   I'm trying to understand what Ardour is doing with audio datapaths.
Maybe someone has a better understanding than I. I want to start with
a mono track for now and expand to stereo later if required.

I create a mono track. I see a single input and stereo outputs.
Panning is centered and there is only a single panner.

Q1: Why does a mono track show two VUs? Just to address the energy
being delivered to the left and right master outputs due to panning?

Q2: Since the mono track is considerig itself stereo at least in terms
of the VUs then where does it become stereo?

a) Before the pre-fader plugins?
b) After prefader plugins but before the fader?
c) After the fader and before the post fader plugins?
d) After the post fader plugins?

e) (my favorite) It depends on the plugins?

Does anyone know?

So to this mono track I tell ardor to apply a 1 in - 1 out plug, such
as 'Signal Sifter'. I see no change in the way the track looks.

So following the Signal Sifter plugin I insert a 1 in - 2 out plugin
like Plate Reverb. Now I see two panners at the bottom, so presumably
the track has become stereo prefader. Is this correct?

For kicks I now add a 3rd prefader plugin - SC2 - which is registered
as 2 in - 1 out. At this point I would expect to have only a single
panner at the bottom but I still have two.

WHY???

Now comes the confusing one. I now remove the SC2 using the cut item
in the menu. I have Signal Sifter and the Plate reverb. I expect that
since the Plate rever is 2 out I should have 2 panners but the track
has shifter to 1 panner?

WHY??? 

What's going on here? Can some explain the datapath model to me?

Thanks,
Mark