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Apogee Interface, Logic Pro X, Axe-Fx II XL+ Trouble shooting clock sources, "out of sync", and USB

Luth2000

Inspired
I'm porting this discussion here from another location, to get more interaction and knowledge. As the title suggests, there is a large collection of Fractal users that run into the same problems when using an additional audio interface (in this case Apogee Element 24). Many searches and threads have been read, but I don't feel there has been a true explanation/solution for what is faced.

I’ve had the Fractal FX 2 XL+ for over a year now, and tried various signal chain setups with and without a 2nd audio interface. I’m now running an Apogee Element 24 via thunderbolt, and using the Axe FX as input through USB. Speakers are running out of Apogee. The audio detail with this setup is amazing and my preferred way to run. (BTW iMac 3.5 GHz Intel Core i7 with 32 gb ram, latest OS, Logic Pro X, Ares firmware for FX XL+)

It seems to be a very common problem that when playing guitar through this chain eventually (after 3-5 minutes) the sound (only guitar input) all of sudden goes into extreme latency (2-3 seconds). The quick fix is to restart the track in Logic Pro and all is synced tight again.

Is it a buffering problem? Can the system only handle so much data before lagging behind? Is it a sync clock problem, that is reset when I restart the play track? Or???

I have all hardware set to 48, and have tried varying buffering settings on all of the units.

I’m not that well versed on clock issues, but I'm reading that the Fractal wants to be the clock source, but the only two options are "Auto, AES, and SPDIF" which claims "no clock source!" when selected. Auto is the one selection that seems to work.

I followed one thread where an owner runs his analog out 1 into the front of the Apogee, while at the same time utilizing the USB connection for other features. I'll try that today, but I'll be surprised it that's the problem/solution. It's curious that when running the system without the Apogee and using the USB of the Fractal only, there is no problem. So somewhere in computer and audio interface path, there is something not jiving.

Back to clock source, should that setting on the Apogee be set to Internal, word clock, or Optical? Internal is the only setting that seems to work.

Of course the 3rd entity is the Logic Pro X program, and I'm wondering if there are some key settings there that I'm missing a subtlety on. I've gone through all the Audio preferences many times, tried different buffering, etc. Buffering numbers are: Logic Pro - 128, Fractal 1024. (I tried doubling those recently with inconclusive results).

The obvious question is: "why does it go out of sync when playing guitar, and why does hitting stop and play agin bring it back into sync"?

Any help here appreciated!
Thanks, Luther
 

GlennO

Fractal Fanatic
It's unlikely to be related to buffer sizes. It sounds like it might be a clock problem, but it's hard to say. Logic does some reset operations when you stop and restart playback, more than other DAWs. The first thing I would try, as an experiment, is: take the Element out of the equation. Plug the AxeFX directly into your computer and see if that works better. Run analog outs from the AxeFX to the Element if you need that for monitoring. If necessary, use headphone out on your computer, again just as an experiment to try to take the Element out of the picture. Assuming that works, plug the Element back in, but only use it for output, and see what happens.
 

vaultnaemsae

Inspired
Are the 2 devices aggregated? If so have you tried drift correction settings and adjusting the master clock device?

If I understand correctly, the clock source setting you mentioned in the Axe-Fx II's I/O is only for SDPIF/AES connections to the Axe itself. i.e if you cabled the Axe up with your interface via SPDIF/AES IN/OUT.
 

Luth2000

Inspired
ok - I just tried running 1/4" instrument cables from AxeFX out 1 (pair) to the Apogee IN 1&2. Dropped the AXE as input device in Logic, and input straight from Apogee (coming in analog). Absolutely no problems, and I must say, sounds killer. I left USB connected to AxeFX to control AxeEdit.

The Pros of this method:
1) It seemed to me the levels of presets lived in their sweet spots.
2) I set the out 1&2 at noon, and it meshed really well with the Apogee and Logic.
3) I can finally fine-tune input level slightly in Logic on the control strips.
4) no annoying 2-3 sec out of sync delay in over an hour of playing.
5) Effects seem more pronounced in sounds.

Possible cons:
1) I still don't know what the problem is with syncing in other configuration
2) Am I sending Logic tempo to AxeFX for delay syncing etc.
3) Interesting that when I went analog in to Apogee, Apogee control and Audio MIDI setup only let me select 44.1 Hz.
4) I'm assuming I can't "re-amp", but I have yet to do that anyway.
5) Others?

I'm interested in your collective additions to pros/cons, as well as still trouble shooting the sync issues. Those that are sending helpful suggestions, are you running Logic Pro and an additional interface?

thanks again for the help,
Luther
 

Luth2000

Inspired
Are the 2 devices aggregated? If so have you tried drift correction settings and adjusting the master clock device?

If I understand correctly, the clock source setting you mentioned in the Axe-Fx II's I/O is only for SDPIF/AES connections to the Axe itself. i.e if you cabled the Axe up with your interface via SPDIF/AES IN/OUT.
Good point on aggregate. I had not set that up. Now I have, but still utilizing analog in from the fractal. Interesting that even when setting details for the aggregate, 44.1 is the only option for the Element now. I guess thats because I'm sending it analog - correct?

I don't have sdpif/aes cables - will that be worth it? I guess I assumed that the same info was being transmitted via USB.
 

vaultnaemsae

Inspired
There's a bit to unpack here. Firstly, I'm not a regular Logic Pro X user but occasionally use it when required. Updating it as we speak!

I'm not sure why you even need the Element 24. I mean, use whatever gear you want by all means!! But it doesn't seem to give you any benefit over using the Axe-Fx USB 'raw' -- other than if you want to use it via the analog ins (as you mentioned) at a sample rate other than 48kHz. Maybe it outperforms the Axe-Fx in terms of roundtrip latency over Thunderbolt? Maybe it's simply for your monitoring setup? I really don't know about that one.

Anyway, if the Element 24 is integral to your workflow and you're happy with using it the way you are now, your problem is solved. But, as far as the Element 24 is concerned, you almost certainly should have other sample rates available to you via the Apogee configuration software. The sample rate bears no relation to the analog input source -- it's just the frequency the device is instructed to perform at. I don't use Apogee equipment but had a quick look at the Element 24 specs online where I read, "AD/DA conversion for recording up to 192kHz/24-bit". Please take a look at the Apogee software again.

FWIW, I don't use SPIDF/AES connections (the only devices that I would like to use in this way have been locked at incompatible sample rates and realtime software conversion does not produce satisfactory results) but if you intend to use S/PDIF or AES, you'll need to find some way to convert from the Element 24's TOSLINK connectors to the Axe-Fx's S/PDIF or AES. There's plenty of info on the forum about these type of connections but I think using them may be overkill. I would stick to the USB connection for the sake of simplicity.

If you choose to use the analog outs of the Axe-Fx into another digital device, you still can do analog reamping with some crafty routing -- but it's a PITA compared to the simplicity of doing it over USB. Besides, I don't think you'll have enough I/O on the Element to achieve that goal without more external hardware! But probably the digital I/O would handle that...see the previous paragraph.

Finally, coming back to my last reply, assuming the Element 24 is critical to your workflow and you are ok with it at 48kHz, you should be able to aggregate it with the Axe-Fx II in the Audio MIDI Setup on MacOS. You could then record both devices simultaneously and have more I/O options.
 
Good point on aggregate. I had not set that up. Now I have, but still utilizing analog in from the fractal. Interesting that even when setting details for the aggregate, 44.1 is the only option for the Element now. I guess thats because I'm sending it analog - correct?

I don't have sdpif/aes cables - will that be worth it? I guess I assumed that the same info was being transmitted via USB.

The sample rate is determined in Logic Pro X.
 

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