HDX Masterbus Latency

[bertanica]

I have been working on an old HD rig and Mac Cheese grater for tracking until recently. The old Mac needed to be serviced so I grabbed an HDX card and a TB2 chassis to run on my 2015 MBP with an I7 and 16GB of RAM. I have mixed fairly heavy sessions on it natively. I set it up to test it for tracking and the difference between the pre-fader headphone mixer and the master out even at the lowest settings is pretty stark. I compared it while playing in the control room and playing to or listening with a click was impossible. I don't recall having this issue in HD TDM, even with many auxes and parallel buses before the master fader. Can anyone speak to a better way of doing this?

Some details: My main converter is Lynx Aurora so it matches the latency of the HDio. I also have an old Apogee AD16x for additional inputs and it also outputs optical to the HP mixers. I believe the master output is running from the AES out on the Apogee into a Dangerous Source monitor and headphone controller. Again the HP mixers have zero or near zero latency. Any help is appreciated.

Also any tips to optimize the laptop to avoid errors during record and playback is appreciated.

[Darryl Ramm]

What are the latencies in #samples... that should help give you a clue what is going on. Pro Tools can measure all that for you.

What plugins are you running and are they native or DSP?

What happens with all plugins removed?

Any internal high latency plugins?

“Even at the lowest settings”... what settings? You mean IO buffer? If you are running a full DSP workflow then IO buffer will not come into it. What other settings?

It’s sure easy to get horrific latency by improper ordering of native and DSP plugins. But native plugins on record enabled tracks get disabled... so hard to guess what exactly you are doing but I expect the root cause is plugins and maybe mixing native and DSP plugins. You might well have excluded all this, if this is all Greek start at the Pro Tools Reference Guide.

You should fully optimize the Mac... if you are getting errors what exact ones, what exact Mac, Pro Tools versions, etc. All the usual stuff, start at “Help Us Help You” up the top of each DUC web page.

[bertanica]

Thanks, I haven't measured the latencies but they seem high. Bad enough that the speakers sound is much later than a picked guitar string in the room, I will try and measure it tomorrow. I understand the ordering of native and DSP plugins which is why this is perplexing.

H/W buffer I tried at the lowest setting, which is 64 samples. Cache was set to normal but I played with it and no change. I have all of the Native plugins set to inactive and I think I even tried removing all of them. I even turned all of the DSP plugins off. Then I routed the guitar straight into the master bus and bypassed the guitar aux group. Still the difference between the master and HP mix remains.

I am running:
MacBook Pro (Retina, 15-inch, Mid 2015)
MacBook Pro (Retina, 15-inch, Mid 2015)
2.2 GHz Quad-Core Intel Core i7
16 GB 1600 MHz DDR3
Intel Iris Pro 1536 MB
Most recent Pro Tools Ultimate

[Darryl Ramm]

The suspect should be plugins in use... could there be plugins you are not seeing? If that is not it then maybe the system or session is totally messed up... Have you trashed prefs? Tried starting with a totally empty session? If there were still plugins in use I would also look at what ADC is showing... but with no plugins ADC should not be an issue.

It will have nothing to do with hardware/interfaces. Cache has no effect on latency. With no plugins or no native plugins IO buffer size should have no effect on latency. If it does then you have a native plugin somewhere.

[bertanica]

Thanks again, Darryl. I did search Avid, other forums, and the web for a solution prior to this thread. I was thinking maybe this was a known issue for HDX that I was ignorant of.

I am using a template, but all of the audio is newly recorded. I will un-hide all the channels to verify but as I understand it, without audio the plugins should not be causing any delay. That is why I suspected it was all of the aux routing. I will probably start from scratch on a template. I did trash all of the preferences a couple of days ago. I will also try the AES output on the Lynx instead of the Apogee and then also try an analog out to compare. Back to troubleshooting.

[Rich Breen]

just unhide all tracks and display delay comp at the bottom of the mix window, then you can easily see where the problem is. Probably some native plug somewhere with a lot of latency.

[Darryl Ramm]

Originally Posted by bertanica

...but as I understand it, without audio the plugins should not be causing any delay.

This statement makes no sense at all. Plugin latency is either largely fixed delay due to algorithms/processing in the plugin, and DSP and native plugins may have delays... you can usually find those in the plugin specs. or you have delays from going through the IO buffer when switching between DSP and native processing.

That is why I suspected it was all of the aux routing. I will probably start from scratch on a template. I did trash all of the preferences a couple of days ago. I will also try the AES output on the Lynx instead of the Apogee and then also try an analog out to compare. Back to troubleshooting.

all the mixer including "aux routing" happens in the HDX DSP mixer. Auxes don't add latency or slow things down, you try to do too much there and you run out of HDX voices. Now stick native plugins on aux tracks, or any plugins with latency and of course you can introduce latency there just like anything else.

You really need to get these concepts into your head so you are not chasing phantoms. Auxes and farting around with digital vs analog outputs is a total waste of time. It's going to be plugins or less likely a corrupt session. Use ADC readouts, measure the latency etc.

[bertanica]

Originally Posted by Darryl Ramm

This statement makes no sense at all. Plugin latency is either largely fixed delay due to algorithms/processing in the plugin, and DSP and native plugins may have delays... you can usually find those in the plugin specs. or you have delays from going through the IO buffer when switching between DSP and native processing.



all the mixer including "aux routing" happens in the HDX DSP mixer. Auxes don't add latency or slow things down, you try to do too much there and you run out of HDX voices. Now stick native plugins on aux tracks, or any plugins with latency and of course you can introduce latency there just like anything else.

You really need to get these concepts into your head so you are not chasing phantoms. Auxes and farting around with digital vs analog outputs is a total waste of time. It's going to be plugins or less likely a corrupt session. Use ADC readouts, measure the latency etc.

Thanks for the clarification on the auxes. I am planning on starting a fresh session today. I have been using HD for 12 years and never had the issue, so I thought maybe something had changed with HDX that I was ignorant of.

On the topic of changing the physical outputs, since converters have different latencies, could it be that the AD16x is introducing the latency? Once audio leaves the card there is a bit more ground to cover. I thought maybe the Lynx might not have the same issue. I ask this because even when I plug a guitar into a DI track and route it direct to the master bus with no plugins on either, the latency remains. I will look at this once I try out a new session and if the problem persists.

[albee1952]

More to consider: latency on the master is not compensated for(and usually does not NEED to be), so any plugins with latency will make the master output later than other paths(like headphone mixes done with AUX sends). If you set(under the VIEW menu) the MIX window to show Delay Compensation, you can see if any master track plugins are causing latency

[bertanica]

Thanks for all the input. I missed a plugin on the master that was bypassed (not disabled) in the template. The delay comp was over 6000 which explains it.