Alesis IO dock ground loop issues

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  • Updated 4 months ago
  • Acknowledged
Hi, I'm using an Ipad Air 2 with an IO Dock II. I have an analog mixer with stereo outs connected to line in of the Dock, and my synths are connected to the mixer with audio cables. There is also a Control Room output from the mixer where I've connected a pair of Audio Monitors.
If the iPad is turned off, with the Dock connected to the mixer (input and output) I haven't any hum or digital noise coming out to the Audio Monitors when I play my synths, but when I switch on the iPad, and I play a song from iTunes with it through the Dock, I hear a subtle digital noise coming out also, and if I use the iPad swapping the screen, choosing for an app, this noise changes accordingly with the graphic redraw of the iPad screen.
So, If I try to record with Garage Band, also this noise is being recorded.
I guess the noise is due to a ground loop which is "closed" through the ground line of audio cables connected to the Dock.
Since Dock power supply is a two prong plug without earth prong, I'm wondering if there is a metallic or ground in the Dock chassis to connect to the earth, to avoid forming a ground loop on audio cables.

What about if I don't use the Dock power supply, but I use the USB connector connected to an active USB hub to power it? Does it make sense as a workaround? Or use a battery as a power supply for the Dock/iPad?

Unfortunately if I don't get rid of this issue, I can't do good recordings...
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Posted 4 months ago

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