VCA masters

Is there any documentation on these? What exactly are they used for?

VCA give another way to controls groups of tracks see:

Thanks for the link, that does help. The main reason for asking is that they don’t change the volume of tracks with fader automation, I was expecting that they would scale the volume accordingly but apparently not. Am I misunderstanding something fundamental?

You can also look at

VCA [not] controlling tracks with automation was a bug in 5.5.0. It’s meanwhile fixed in ardour-git ( and will be available in the upcoming 5.6 release

@x42, I just built ardour from git and it seems broken to me. Track has fader automation, connected to a VCA with VCA level all the way down. It causes track volume to go to all the way down but there is audio still playing somehow.

The automation track’s fader in that screenshot shows “-nandB”; there’s clearly still some kind of bug in calculating the overall gain of an automated track that’s also controlled by a VCA at -inf.

will investigate and fix …

from a little experimenting, this issue seems to only occur at session startup. if i change fader automation from “Play” back to “Manual” then back to “Play”, it works OK.

Could you confirm that this reset of the automation state works for you?

The problem here arises from restoring a session with a VCA at -inf dB. In fact, the problem is deeper than this: saving and reloading a session with the VCA(s) at any position other than the one they had when they were first assigned will result in different settings than they had before reloading. A solution is required, but doesn’t seem trivial.

@paul, resetting the automation state doesn’t seem to affect anything for me although I did find that resetting the VCA does mute all sound - sometimes. In the same session as the image above, if I move the VCA to 0db and then put it all the way down again and play sometimes there is no sound at all but it is inconsistent and sometimes it goes back to the way it was and has no effect. I don’t believe it is anything to do with restoring the session with the VCA at -inf dB, the above image was taken with no save/restore event since the VCA was created.

I have a fix already in git; last night’s nightly build should show this problem as resolved.