High Pitch Interference using Mix Pre-3 Stereo Out

S

SDub

Well-known member
I am currently using the stereo out of my mix-pre3 to feed the mic input on my GH4. My exact config is like this: http://cdn.sounddevices.com/download/guides/MixPreSeries-PanasonicGH45.pdf

I've discovered that when I plug any aux cable from the stereo out of my mix pre 3 to the mic input of my GH4, a high pitched interference occurs. I've tested this with 2 different cables, and it also shows up in the recording. I was curious if I'm doing something wrong, or possible my mix-pre 3's stereo out is faulty. When I bypass the mixpre3 and just plug a mic straight into my GH4, there's no high pitch interference.

Thanks for any help!
 
I'm not that familiar with SD's MixPre series output settings, but common questions would be: Is the MixPre 3 stereo output mic level?. If not and if possible turn down the stereo output to mic level. Basically, you will likely just need to attenuate the stereo output on the MixPre to mic level. You should disengage any mic Plugin Power if the GH4 has it as well.

Addendum: I see in the MixPre 6's manual it has an 'Advanced Mode> Sub Menu> Outputs setting' "Stereo out L/R source select and Stereo out gain". So I would look for that, and select 'mic level' or the lowest output volume to start with, feeding that type of cam.
I would assume MixPre 3 has the same or similar settings.
BTW, what mic are using with the MixPre and does it have an XLR output?
 
Last edited:
Solved the issue. It was a ground loop issue. My camera was mounted on top of the mix pre-3 causing a shared ground. Separating the two made the interference go away.
 
I'm not exactly sure. Electro-magnetic or some kind of RF radiation. It's a shielding issue though with the camera.
 
Now a ground loop would open you up to that. But I agree that it's probably not a ground loop.
All these devices are esentially computers now and computers run at high frequencies. I would be really surprised if the MixPre has a shielding issue but the camera might well have one.
 
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