Is anyone experiencing audio dropouts?

The Apollo is a Thunderbolt 2 connection. The FFACE 800 is a Firewire 800 connection (IEEE 1394B). The only USB connection on the AUDIO side is the AXE FX III.

My other MIDI stuff (external to the box) is a Kurzweil PC3K7 (USB), Roland 3080 (MIDI via a 4-port USB interface [actually the only one I have that still seems to work with Mac OSX] - so still actually USB), an Akai MPK 261 controller (USB), and the Mackie Control (connected to the 4-port MIDI/USB interface).

After hours of troubleshooting, I _may_ have gotten it working. The big changes were primarily:

1. Changed FW800 port on my OWC TB2 dock to use just a TB dongle/firewire converter.
2. Also - I ran a SPDIF line from my FFACE800 to the AXE FX III's SPDIF input.

This way, theoretically the FF800 is the master, sends sync via ADAT light pipe to the Apollo, and also sends sync to the AXE FX 3 via SPDIF (RCA).

Keep your fingers crossed - I know I am. So far I have about 3-4 hours of testing with no glitches.

First, I believe you're on the track here. I have a Lucid GENx6-96 as a master clock, but something is wrong there. I have tried multiple BNC cables and am still getting questionable clock signal from it (shows as lock/sync popping in and out in my interface). As a result, I am using my RME Fireface 800 as a clock master. I also send an ADAT signal to my Apollo Twin for sync, and all seems to be well (the Apollo never loses sync).

This is what is starting to make me think it's not a clocking problem, but random audio dropouts in Logic. Admittedly, it still could be either. I have also tried changing my recordings to 48K (used to use 44.1) because one of my external pieces (Axe FX III) is fixed at 48K.

The Mac mini I use is fairly beefy (3.0Ghz/16G RAM/1TB SSD with an external USB3 SSD), so that and the fact that I never had dropouts before leads me to believe the system is probably okay.

I have pretty much run out of things to try/change. I even tried setting Logic sync to EXTERNAL/FREEWHEELING and no luck.

In the case of rolling back to 10.4.4, where would I go to grab that? I don't think it's still on my system. I would love to give that a try.

Any other ideas are super welcome - I have been pulling my hair out for days now.

Thanks!

Well - I'm nearly hairless.

I decided to simplify. I removed all interfaces from the composite device except my Apollo, and then listened to drum loops through it. Nearly perfect, although I did believe I heard one glitch.

I added another interface to the composite device (FFACE 800). So far so good. Then I added my USB-connected Axe FX III to the aggregate interface. Seemly good, so I recorded some junk tracks. With a MIDI drum track, and 3 audio tracks all seemed to be going well until about the 8th play-through. At that point, I got a lot of fuzz and noise near the end of the tracks. Played it again and it was fine.

I also got the dreaded MIDI/Audio sync error, and according to it a sample rate of 41,430 was detected. ?!?

So - whatever it is is highly intermittent. As I said, it happens in random places at random times.