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kdog

G10 Ground Loop Noise when driving two devices

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Hey All,

 

Just picked up a G10 to setup my home practice and recording rig and am impressed so far. One issue I have though is driving two devices at once (Audio Interface and an AxeFx 2)... using the XLR for one and 1/4 for the other yielded some serious hum and a pulsing noise.

 

I tried unplugging the XLR out and using a passive A/B switch to select the device (I only need one at a time) but that doesn't work either. It does this even when the AxeFx is powered down, too, if both are plugged in the monitors produce noise. I figure this makes it clear the noise is on a ground loop somewhere since A/B box is going to share a common group line regardless of which unit is selected.

 

I'd like to keep both connected, so I was thinking about maybe picking up a different box. Maybe an active switcher like the Boss LS-2 or the Radial Bigshot I/O which has an isolation transformer on one of its outputs.

 

Anyone have any ideas or tips? Anyone solve the issue a different way?

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Use the same Power Strip (ideally a conditioned one) to connect the AC power for all your devices! Additionally, a USB Battey pack (rechargeable Lithium) may be used to power your G10 Receiver base so it need not be connected to the AC power.

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Hey All,

 

Just picked up a G10 to setup my home practice and recording rig and am impressed so far. One issue I have though is driving two devices at once (Audio Interface and an AxeFx 2)... using the XLR for one and 1/4 for the other yielded some serious hum and a pulsing noise.

 

I tried unplugging the XLR out and using a passive A/B switch to select the device (I only need one at a time) but that doesn't work either. It does this even when the AxeFx is powered down, too, if both are plugged in the monitors produce noise. I figure this makes it clear the noise is on a ground loop somewhere since A/B box is going to share a common group line regardless of which unit is selected.

 

I'd like to keep both connected, so I was thinking about maybe picking up a different box. Maybe an active switcher like the Boss LS-2 or the Radial Bigshot I/O which has an isolation transformer on one of its outputs.

 

Anyone have any ideas or tips? Anyone solve the issue a different way?

So if you only have one device plugged in to either the XLR or 1/4", there is no noise? Below is from the G10 FAQ guide, so it should be fine. MusicLaw may be on to something. I have come circuits in my house that have CFL lighting and some compact LED lighting on them. I can't use any of my audio gear on those circuits because of the noise that is produced from those stupid cheap lighting driver circuits. 

 

"Q: Can I use both the 1/4" output and the XLR output at the same time?

A: Yes, they can both be used simultaneously."

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Thanks for the tips... I tried the XLR and 1/4" simultaneously but no-go. They are both on the same strip... Will try battery power for the G10 base, too, before sinking anything into more hardware. Thanks!

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Does the AxFx have a ground lift switch? Helix does. Not sure if that would open up a ground loop. 

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I have tried using the XLR out direct to my A&H QU-16 desk just to see if there were any noticeable differences in tone between the 1/4" and XLR outputs. The XLR was unusable due to hum, all equipment were plugged into the same power source.

 

I have a mate with the same set up as me and he also tried the XLR out, he suffered the same problems, even swapped cables to make sure that wasn' the fault.

 

Who know's. 

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Make absolutly certain that there is no 48v Phantom Power being supplied by the other devices from their XLR Inputs!

 

If you have ruled out any bad cabling, and you power the G10 via a battery pack (instead of AC line power or your computer's USB jack), and you are still getting any noise from either of the G10's outputs, either you have a faulty G10 kit, or your other conneced piece of gear, is the source of the noise. This also if you have ruled out the possibility that you are in an unusually high RFI (Radio Frequency Interference) area.

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 This also if you have ruled out the possibility that you are in an unusually high RFI (Radio Frequency Interference) area.

If you are running CFL bulbs or LED lighting in the area, turn off the lights to see if your noise goes away. Cheap non-incandescent lighting can be pretty noisy in some audio related equipment. 

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