Not sure if this is the right place so please let me know if not. I'm attempting to record two USB mics into garage band on a macbook pro.

I've created an aggregated device with the two mics in it and then in garageband I set one mic to one channel and the other to the second channel, the trouble I've found is the minute I start recording I can see that one mic is delayed by a fraction of a second. If once I'm done recording I drag them into alignment at the start I then find further through the track that it seems to have gone out of alignment again and the 'slow' track is again lagging behind.

Has anyone experienced this before and do you have any suggestions how to get around this? The tracks themselves are pretty standard voice tracks, no big effects or anything that I'm aware, the mics are in different USB ports and are different makes, could that make a difference?


  • 2
    It ought to enable automatically, but check you have Drift Correction on for all except your master clock device in AudioMIDI Setup.
    – Tetsujin
    Commented Nov 15, 2018 at 12:14
  • Is it possible to separately set the sample rate for two different USB mics? I’ve never used a USB mic so I don’t know, but two different sample rates would definitely have this effect. Commented Nov 15, 2018 at 16:09
  • @ToddWilcox - if you set up an aggregate device, one becomes clock master, the other slave to that - the OS/audio app then sees 'one device' [in theory].
    – Tetsujin
    Commented Nov 15, 2018 at 16:23
  • I don't think I have drift correction on I'll try that next time! I'm mega confused by how they are out of alignment but when I drag one track into alignment it then later manages to slow down again :/ Could having both go through the same USB port via a hub help? Would having two of the same mic help? Thanks for your responses so far!
    – MorkPork
    Commented Nov 16, 2018 at 8:58
  • I set drift correction on and still things were out of alignment, however I then experimented with two identical brand microphones and it seemed to work much better so I'm going to buy a second razr mic and hopefully that will resolve my issues
    – MorkPork
    Commented Nov 26, 2018 at 15:35

1 Answer 1


I don't think the difference in model should effect how your mic signals are tracking. My first thought was the input source, but since you're getting signal on both channels then that feels like it's working also. You might want to try going into your audio preferences and finding your buffer size. For just two signals, it probably shouldn't be 1024, but maybe 512. Someone definitely correct me if I'm wrong, but this seems odd.

If that doesn't help, check your channel strip settings. Out of curiosity, what is your interface set up like/what is the aggregated device that you set up looking like?

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