Zoom L20 Noise Issues When Connected to DAW

Bogg

New member
Hi there, I'm after some advice and solution to a problem I'm having. I have the Zoom L20 mixer/interface/recorder and I have just purchased an Apple iMac to use GarageBand on. When I activate the L20 as a USB interface in GarageBand I get a high pitched sound coming from the monitors. Could it be a ground loop noise and if so would a USB Isolator fix the problem or not?
I have all the equipment plugged into a double power point in my studio and this noise only happens when GarageBand asks me if I want to use the L20 as a usb interface and I click yes.
Any suggestions/fix would be much appreciated. Thank you.
 

keith.rogers

Bobby'); DROP TABLE USER
The monitors are connected to line outs from the L20, and they don't make any noise when used for playback there, correct?

All the faders down on the L20? I.e., is the noise constant regardless of level control on the L20? How about the GB master level?

Can you run a long extension cord from the iMac or L20 to some other outlet, ideally on a different circuit in the house?
 

Bogg

New member
The monitors are connected to line outs from the L20, and they don't make any noise when used for playback there, correct?

All the faders down on the L20? I.e., is the noise constant regardless of level control on the L20? How about the GB master level?

Can you run a long extension cord from the iMac or L20 to some other outlet, ideally on a different circuit in the house?

Hi, yes the monitors are directly connected to the L20's line outs and they are quiet as in no noise when playing back. I only get the noise when I activated the L20 as the usb interface in GB.
Yes the noise is constant regardless of the L20's fader position. Havent yet tried the GB master volume but I think the noise will still be there. Will test that out.
I can try plugging into another outlet and see what happens. I'll let you know.
Cheers, thank you.
 

keith.rogers

Bobby'); DROP TABLE USER
If the noise is constant when the L20 faders move, it must be when the device is selected as the *output* for the DAW, but then I'd expect that behavior whether using GB or setting it globally in the OS X Settings/Sound, i.e., take the DAW out of the equation. It does suggest an electrical leak/noise/interference getting between/to/from the computer to the monitor speaker via USB cable, so trying even just a different USB cable, moving the power cables, turning off other devices/lighting on the circuit (in case something else is actually introducing the noise), etc. All the usual suspects.
 

Bogg

New member
If the noise is constant when the L20 faders move, it must be when the device is selected as the *output* for the DAW, but then I'd expect that behavior whether using GB or setting it globally in the OS X Settings/Sound, i.e., take the DAW out of the equation. It does suggest an electrical leak/noise/interference getting between/to/from the computer to the monitor speaker via USB cable, so trying even just a different USB cable, moving the power cables, turning off other devices/lighting on the circuit (in case something else is actually introducing the noise), etc. All the usual suspects.

Thanks, I'll try those suggestions and see if I can isolate what the cause is. Appreciate your help.
 
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