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  • Peter Schwartz
    Posts: 545
    Joined: Sep 15th, 2007, 06:04
    Re: Logic Pro Aggregate Audio Device
    Thanks for reiterating the descriptions of what we're seeing here. It's almost 5 AM and I'm a bit loopy tweaking strings, so, like "I knew that" LOL but I just couldn't quite remember... One of the problems with aggregating devices that crops up is exactly what you're seeing here: a difference -- even a very minute one -- between the two devices being aggregated. It's almost as though (i.e., conjecture on my part) the inputs from the second device tend to lag behind the first device when they're aggregated. In other words, aggregation allows you to consolidate multiple interfaces, but the correlation (or resolution) between them isn't always perfect to the letter. The other possibility (again, conjecture) is that there's a slight difference in the A/D processing times between the first and second units. I'd be curious to see if swapping them around and then repeating the test produced the same 1-sample-off result. But whatever the case may be, and all my conjecture aside, my main point in having you test these things out was to see IF there was indeed any timing differences between the units. I think the key here wouldn't be to worry so much about the 1-sample difference between the units as it would be to just make sure that anything that needs to be phase coherent to the letter gets recorded on one unit. For example, if you were to record a rhythm section ---- 8 drum mics, 2 guitars, bass, 2 for piano, 3 on the organ player's Leslie, that's 16 inputs all on one unit for which you know that all the inputs will be phase coherent to-the-sample. If your scratch vocal is coming in on input #1 of the 8-input unit, well, he/she's going to be one sample off from everyone else. Probably not enough to worry about. Now... if worse comes to worse, you can always shift the 8 tracks from the 8-input unit back one sample in the arrange page once you're done tracking. But I have the feeling that as long as you know what the discrepancy is, you'll be able to select inputs accordingly so that you won't end up with phase anomalies when tracking all 24 at once.
    Reply
  • msandm
    Posts: 72
    Joined: May 26th, 2011, 12:31
    Re: Logic Pro Aggregate Audio Device
    Awesome, well thanks a bunch for your help. It's really opened me up to the pros and cons of this setup and how to deal with them all and manage it all more efficiently. Hopefully it all goes smoothly from here on. Thanks again, Damian
    Reply
  • msandm
    Posts: 72
    Joined: May 26th, 2011, 12:31
    Re: Logic Pro Aggregate Audio Device
    Hey, Thought you might be interested in this, regarding the whole syncing of the Aurora 16 and 8, latency issues etc. I had posted a similar topic on the Lynx website and posted screen shots of the delayed audio files etc and this is what they said: "That is normal when one signal path is through an A/D conversion and another is AES transmission." Pretty weird, so it's just something I have to accept I guess. Cheers, Damian
    Reply
  • Peter Schwartz
    Posts: 545
    Joined: Sep 15th, 2007, 06:04
    Re: Logic Pro Aggregate Audio Device
    Hmmm! Curious info from the Lynx website. All signal from all inputs (both units) has to be A/D'd (naturally) so I'm not sure why there would be a 1 sample lag with the second unit. They're both probably connected to your system in single wire mode, yes? Anyway, curiosity aside, my feeling is that if you can plan your inputs along with the notion that phase coherent source can't be split across both units, the one sample difference won't really matter very much between the units themselves.
    Reply
  • msandm
    Posts: 72
    Joined: May 26th, 2011, 12:31
    Re: Logic Pro Aggregate Audio Device
    True, I'll just have to keep it in mind and plan appropriately... And yes, I'm in single wire mode. Cheers, Damian
    Reply
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