Ask Different is a question and answer site for power users of Apple hardware and software. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have a Mackie Onyx 820i mixer with a FireWire interface that I connected to my iMac. I can plug my guitar in and play through it just fine (using Logic Pro). I can play youtube videos in browsers, etc. The problem I have is when I try to do both at the same time, the audio through FireWire (my guitar), is distorted. For example, I can watch a quicktime movie, then start playing guitar, and the audio is just all messed up.

Is there anything I can do to fix this? I updated the firmware on my Onyx. I just upgraded to Lion, and while this issue only sometimes happened before, it happens all of the time now since the Lion upgrade.

share|improve this question
What are the specifications on your iMac? Which model, what CPU and speed? How much RAM do you have? Are you recording to an external hard drive, and if so, what are its specifications (interface, rotational speed, does it have a separate power supply and fan)? Are you monitoring through external speakers through the Onyx' output, or listening on the internal iMac speakers? – user9290 Sep 30 '11 at 17:51
Second, why do you need to play or record your guitar through the iMac while playing a YouTube video? – user9290 Sep 30 '11 at 17:53
When you export the audio file (as mp3) do you still get distortion? The answer to this will probably help, as we can figure out whether it's the software or hardware. – SoFLy Oct 1 '11 at 2:45
Post a .wav recording of the distortion? There are many different effects that are described as "distortion" – endolith Oct 11 '11 at 19:31
I've got the same problem! I use the Onyx 820i with Logic Pro. Worked fine until today! The output through firewire will sound distorted (like a metallic ring sound is added) when I use Logic Pro. When I play something through the Mackie from iTunes or Garageband it sounds fine, but when I play something from iTunes and Logic is also opened, the distortion is back. When I record something, and bounce it, the audio is fine so it's not recording this distortion. Basically, everything works fine, unless Logic is opened, then the output is distorted. Were you able to solve this problem? I'm thinki – user41402 Feb 8 '13 at 3:23

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.