VCA Masters and Latency

[wyman]

Hi Folks,

I've been having trouble with VCA masters and sessions with high (>4000 samples) latency. When I'm writing automation using a VCA fader, as I'm moving the fader / hitting the mutes, the channels assigned to that VCA group behave in sync. When playing back, though, the individual channels move noticeably slower. I hesitate to call this an ADC thing, because even if I turn off ADC, the behavior is consistent.

I reproduced the behavior in a new session by creating two new audio tracks, assigning them to a VCA group, then putting some heavy-latency plugins making for a few thousand samples of delay on one of the tracks. Same thing: the individual tracks move noticeably later than the VCA does.

I'm using A C24. I see the discrepancy both in the mix window and on the C24, though it seems a little more obvious on the C24.

Maybe this is exactly how VCA's are supposed to work and I'm just a dummy, but it's making for some clumsy automation passes.

Anyone have any insight?

Thanks!

HD Native
Mac Pro Trashcan 3.5 GHz 6-Core Intel Xeon E5
Pro Tools 12.8.3
OSX 10.12.4

[its2loud]

You need to be running PT 12.8.2 or later. The initial 12.8 version broke the VCA function. This may, or may not be your issue.

[wyman]

Sorry, I'm on 12.8.3. Will edit OP for clarity. Thank you for the insight.

[wyman]

Talked to Avid CS this AM, they told me to upgrade to 2018.4 to see if the problem persisted. It did, and in troubleshooting, I found some odd behavior.

2 aux tracks assigned to a VCA Master, 4 instances of Maxim on one track to incur some latency.

With delay compensation off, assigned aux tracks move in sync with VCA fader

Turn on delay compensation, the assigned tracks are noticeably behind.

Turn off delay compensation again, the assigned tracks continue to be behind.

Here's where it gets real weird:

Remove all the plugins, assigned tracks are still behind VCA master.

I made a little video to send them, and I'll share it here, too, in case anyone has any insight:

https://www.dropbox.com/s/ohp7k7jxjk..._5188.MOV?dl=0

[Sounds]

I want to scream with you!!!!

I don't have a great desk like you but ADC is causing me to lose my hair!!! the minute I turn on ADC everything is behind! if I turn off ADC everything is ok! but with the regular (no adc)!!!

I think its a bug! FR!!!

[wyman]

This has now been logged as a bug: ARST-1304. We’ll see how long it takes to fix.

[TOM@METRO]

Originally Posted by wyman

This has now been logged as a bug: ARST-1304. We’ll see how long it takes to fix.

Thanks for pushing this. I'ts very helpful.