Confused about how delay compensation works on aux vs. master fader

[jsbach]

I send all of my tracks to an aux called “mix bus”

the “mix bus” aux sends to Out 1-2

I have a few UAD plugins and Pro-L 2 on the “mix bus” aux track. On the aux track the delay compensation is 8839 and the 'dly' indicator has turned red.

The manual says that the maximum delay available is 16,383 samples at 44.1/48 kHz

My session is 48 kHz. If 16,383 is the maximum delay, then why is 8839 making my aux's dly indicator red?

What confuses me even more is that I tried moving all of the plugins off of the aux and onto the master fader. That fixed the problem. After removing the plugins and placing them on the master fader, the "mix bus" aux turned green again. The master fader's dly indicator now reads 8839, but it is orange.

Why is the exact same delay amount showing as orange on the master fader, but red on the aux when using the exact same plugins?

I'd really appreciate if anyone can help me understand the logic here. I reread the delay compensation chapter in the manual and I am still confused. I don't see any mention of aux and master fader's behaving differently in regard to delay compensation.

[Darryl Ramm]

Pro Tools version? Native? HDX? Interface? IO Buffer size?

Delay comp on the master fader/output? Which other outputs have signals going places? If there is one output/Master Fader, delay comp can't do anything to compensate for latency on it, it can't make your signal travel back in time. Orange latency indicators just means the track is the highest latency in the session

A "few UAD plugins"... and some UAD plugins can have horrendous latency. So be careful there. And again what IO buffer size are you running at...

And you are using an Aux without a live input, so AFAIK it's going to operate in the high latency/large fixed IO buffer domain, assuming you are running native (non-HDX). This is likely the root of your problems.

So why do this with an aux? Just send track outputs to a mix bus. KISS. And then play around with a trivial test session and ADC.

[albee1952]

AFAIK, latency on a master track is not compensated for(by design)

[Darryl Ramm]

Just advice for working with ADC, but look at your plugins and what latencies info the vendors document (UAD documents this very well), and see if what is being reported in Pro Tools is what you expect.

I've already mentioned UAD plugins potential high latency (for their upsampling and lookahead based plugins) and the often inherent need to run large IO buffers to support UAD plugins... but you also mention FabFilter Pro-L 2... a limiting plugin with potentially very high latency. And if running at those high latencies not something you are going to compensate for, its intended to run on the output uncompensated.

[jsbach]

Originally Posted by Darryl Ramm

Pro Tools version? Native? HDX? Interface? IO Buffer size?

Delay comp on the master fader/output? Which other outputs have signals going places? If there is one output/Master Fader, delay comp can't do anything to compensate for latency on it, it can't make your signal travel back in time. Orange latency indicators just means the track is the highest latency in the session

A "few UAD plugins"... and some UAD plugins can have horrendous latency. So be careful there. And again what IO buffer size are you running at...

And you are using an Aux without a live input, so AFAIK it's going to operate in the high latency/large fixed IO buffer domain, assuming you are running native (non-HDX). This is likely the root of your problems.

So why do this with an aux? Just send track outputs to a mix bus. KISS. And then play around with a trivial test session and ADC.

Pro Tools Ultimate 2021.12
Apollo Twin
IO buffer size - 1024

Thank you for explaining. I realize that I wasn't using common sense when thinking about the master fader's delay compensation. It didn't initially occur to me that there is no delay compensation on the master fader by design. It makes sense now that I think about.

I was taught to put all of the mix bus processing on an aux instead of the master fader. Mostly because of the master fader being pre-insert. So, I never have any plugins on the master fader. All of my tracks end up at a final mix bus aux.

That makes me wonder. If you only have one master fader in your session, couldn't you just always disable delay compensation on the master fader will no issues when mixing?

If I have no plugins on the master fader, could I safely just disable delay compensation on the aux that I use for mix bus processing? That way high latency plugins would never be an issue?

[Ben Jenssen]

Originally Posted by jsbach

Pro Tools Ultimate 2021.12
Apollo Twin
IO buffer size - 1024

Thank you for explaining. I realize that I wasn't using common sense when thinking about the master fader's delay compensation. It didn't initially occur to me that there is no delay compensation on the master fader by design. It makes sense now that I think about.

I was taught to put all of the mix bus processing on an aux instead of the master fader. Mostly because of the master fader being pre-insert. So, I never have any plugins on the master fader. All of my tracks end up at a final mix bus aux.

That makes me wonder. If you only have one master fader in your session, couldn't you just always disable delay compensation on the master fader will no issues when mixing?

If I have no plugins on the master fader, could I safely just disable delay compensation on the aux that I use for mix bus processing? That way high latency plugins would never be an issue?

I'm not shure what you're talking about. I also use an aux as my master, and have done so forever for many reasons; pre-fader plugins, routing options, and more. The master fader for your output is just a volume control. It doesn't have latency in relation to other tracks. You don't even have to have a master track in your session. The sound will just pass to the output at full speed. Or you could have one for every output in your I/O setup. Don't bother with master tracks, use a volume control. Or use the 'master' aux. Master tracks are useful for some specific situations when you need to manipulate the digital output of the PT mixer, that's another thread.

[JFreak]

Originally Posted by albee1952

AFAIK, latency on a master track is not compensated for(by design)

True. Master Fader is not a normal channel, it just gives you extra control on outputs. Can insert post-fader plugins, can manipulate levels. That is it. No delay compensation. Master Fader means output point of a mixer, whether internal (buss) or external (physical output). Everyone should understand this concept and if not, learn about it.

[jsbach]

Originally Posted by Ben Jenssen

I'm not shure what you're talking about. I also use an aux as my master, and have done so forever for many reasons; pre-fader plugins, routing options, and more. The master fader for your output is just a volume control. It doesn't have latency in relation to other tracks. You don't even have to have a master track in your session. The sound will just pass to the output at full speed. Or you could have one for every output in your I/O setup. Don't bother with master tracks, use a volume control. Or use the 'master' aux. Master tracks are useful for some specific situations when you need to manipulate the digital output of the PT mixer, that's another thread.

I'm probably overthinking and overexplaining. I tend to do that. My question is really that if I use an aux as my master, does it really matter if I exceed delay compensation on that aux? Can I just leave it 'red' or disable delay compensation on it?

[JFreak]

Originally Posted by jsbach

I'm probably overthinking and overexplaining. I tend to do that. My question is really that if I use an aux as my master, does it really matter if I exceed delay compensation on that aux? Can I just leave it 'red' or disable delay compensation on it?

Whatever is your master output (as in you print it or listen to it) does not need compensation.

[jsbach]

Originally Posted by JFreak

Whatever is your master output (as in you print it or listen to it) does not need compensation.

So, if my mix bus aux has a lot of high latency plugins and the dly indicator turns red that is no problem at all?

The red indicator led me to feel like I'm doing something wrong which triggered all of this overthinking.

Thank you for taking the time to help. I appreciate it.