Delay Compensation erratic behavior

[wyman]

Hi all!

In the past couple of months, I have been having some really odd behavior involving delay compensation. Start a mix from scratch, finish, everything great. Close it. Start next mix, finish, everything is great. Go back to first mix, and there's some serious flamming happening in the drums. Delay Comp light is green, but it is clearly flamming.

My system:

Mac Pro Mid 2010 3.33 6 Core
OS 10.10.5
32 Gigs ram
PT HD Native
Pro Tools HD 12.5.2

I also have a UAD Octo PCI card.

The details:

-I do some pretty elaborate bussing, and the tracks upon which this is occurring are the furthest from the actual mix bus (maybe 4 or 5 busses deep). There's also some parallel send and return stuff going on, some of which involves the UAD card, so there's some serious delay compensation going on, north of 15000 samples.

-I notice it very clearly between a recorded drum and a layered sample

-Sometimes simply closing the session and opening it again fixes it, but upon further troubleshooting, I can fix it by deactivating plugins (control command click), and reactivating them, but not always, and sometimes, it takes a few tries of deactivating and activating for it to right itself.

-In some instances, I can definitely see the numbers in the delay compensation display change, and the culprit tracks definitely have different values when they sound "right" and when they don't, so it would appear that something is erratically reporting delay compensation.

-Deactivating and activating the plugin while the Pro Tools is rolling seems to increase my odds of getting it to sound right.

-It's usually off by about 2000 samples in this session, which is 88.2 32 bit

-That said, it has also occurred in sessions at 48/24

-At first, I thought it may have something to do with Drum Leveler, as we recently installed it, and it brings a fair bit of latency to the party, but I just had it happen on a session with no instances of it.

-Here's a super nerdy detail: In these instances, I have two microphones each on kick and snare, feeding a bus, then a sample. The sample and the "mic" bus then feed another bus (the reason for this is to be able to easily eq the sample or the mics separately. When I take these sources out and feed the main output, they're fine, and the mics and the sample show the same delay compensation. And I can gradually put them further back in their busses, and they show identical delay compensation, until they get to where I initially had them in the mix, at which point the mics show no delay compensation and the sample reports about 2000 samples - about the same amount of time as the offset causing the flamming. This really puzzles me - when I have these tracks - one aux fed by the kick miss, one audio track with the sample - feeding the stereo outputs, they report the same delay, but five busses deep, the audio track with the sample has an additional 2000 samples of delay compensation, even when I load the session with no plugins and deactivate the sends.

So clearly, there's some erratic stuff going on with delay compensation reporting and busses. Is there a limit with how deep busses can go? - in this case, I've got five busses between the source audio and the final output. I've been using this routing for a decade, but never with this much delay compensation. Anyone else experience anything like this?

Apologies for the long post. Wanted to provide as much info as I could.

Cheers,

wyman

[albee1952]

Personally, I would simplify. But, having said that, look for a bus assignment that doesn't have a complete path(as in, a send or output set to a bus, but no track set to RECEIVE that same bus. Or vice versa). Sometimes I get almost 2000 samples of compensation, and deleting a bus as described above will make that erroneous compensation go away

[Eric Klinger]

Hi Guys.

I too am having the same issue - popped up with PT 12.8 and use a less, but still involved bus routing.

For example, 2 or 3 kick mics route to a single bus for processing at the single drum level (same with snare miss, all toms etc). After that, all bussed drums go to a final stereo bus for overall drum processing (parallel comp etc).

There is some crazy PDC issue with plugins that obviously report a latency (i.e. UAD-2).

And much like @wyman the behaviour does not happen every time... seems more like it is doing it on PT 12.8 sessions, where previous sessions open fine.

Doe this make any sense??

I have check for stragglers or unassigned busses and they do not exist in my sessions... we're talking modest 24+ track sessions after bussing.

[wyman]

I went through some pretty thorough troubleshooting with Avid. They were able to reproduce it and logged it as a bug, but were unable to offer any ETA on a fix.

The BUG number is : PT-226186.

I've had to adapt to simplified routing so that the problem doesn't rear its head.

[Eric Klinger]

awesome... thanks wyman!!

[martthie_08]

same problem here, PT12.8 on HDX with UAD Octo and UAD Quad cards.

in my case, it even shows up during playback, happens about 4 times a day when mixing, quite annoying!

my "solution" is to toggle the H/W Buffer Size (going back and forth between 256 and 512), then it goes back to normal.

I believe it is an issue with UAD integration.

[mrkatok]

seeing exactly the same problem with Pt 12.6.1 and UAD apollo 16 and/or satellite ..I record uk broadcast and have quite involved bussing ..any record busses post my main output (which includes UAD mastering ) introduce delays as posted here. Have done extensive test with drives/bussing etc. Interestingly if i bounce to disk rather than record to a track then the delay is slightly reduced but 33ms seems to be record delay 1567 samples when i record to a track. Doing drop in mends for me is a pain as I am working with picture sync so have to nudge not only my full mix back in sync but subsequently all drop ins. I regularly use the UAD in live tv mixing (AES and analogue rather than thunderbolt obviously) and there are no similar issue there ...interesting to see if this gets UAD or Avid interested?hoping so as it would really help my workflow ...

[Dan IceWood]

12.7 updated the bussing and ADC so that mentioned issues no longer exist. Just do the update.