Reopening sessions have ring-modulated distortion

[SomeOtherGuy]

When open about half of my sessions, upon playback the session plays but it's distorted with a ring-modulated type of sound. The fix is to go into Playback Engine and reselect anything, such as buffer size, and then after it resets, everything is fine for the rest of the time I'm working in that session, until I close and reopen it. This has been happening since I got my system about 9 months ago and I've just learned to live with it, but is there anything I can do to fix this?

Hardware is an Apogee Symphony with Symphony 64 Thunderbridge and a 2014 Mac Pro.

[DetroitT]

newest drivers?
Try a different TB port/bus
tekrevue

[syMPh]

i don't know what the issue is but i know my symphony / PCIe 64 card creates the same issue sometimes which is fixed by changing buffer ... it always takes something to trigger it like instantiating a new plugin or changing an output while playing back but once it's there it won't fix and changing buffer (or resetting ) makes the anomaly go away...

i don't know what causes it or a fix sadly because i thought i was the only one... it does seem to happen less often now on 10.9.4 and 11.2.1 though...

have you had any luck diagnosing?

[amazingrugs318]

Do you have Autotune on any of your tracks? I get a similar sound to you described when opening certain sessions that have Autotune. Haven't found a way around it other then closing and reopening. Yet another one of the strange occurrences in the wild word of Pro Tools.

[SomeOtherGuy]

I've been applying Autotune via audio suite, so no active instances in any of the sessions.

[midnightrambler]

You can get this type of ring-modulation if you try to run different sample rate, e.g. if you shove a 44.1kHz digital signal into a digital input that's expecting a 48kHz. What I suspect is that at some point the wrong sample rate is initially booting up, like maybe your clock settings are defaulting to the wrong setting or something along those lines, which then gets corrected when you open the playback settings and all parameters are reset. Is there an Apogee software app that you can open to set that its default is the same as your sessions? Anything else you can open in standalone mode to check that the sampling rates are the same? Obviously all this stuff should just default to the right setting but you never know with 3rd party stuff.

Apologies if this is barking up the wrong tree!

[SomeOtherGuy]

That sounds like a good possibility. But before I open any the problem sessions, I can see the Symphony I/O stays at 48K from before and after opening the file. Still sounds like it could be related to this though...