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PostPosted: 05 Nov 2014, 06:16 
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Joined: 05 Nov 2014, 06:09
Posts: 1
Hi all,

I'm placing into a rack enclosure two old microphone preamps pulled from an odd vintage console. These beasts sound really good, and I would like to add a 48V phantom supply circuit, so I found and already built this little phantom powering project:

Image

My problem is that these Mic Preamps are positive grounded, so they carry the supply voltage (24V DC) to the microphone XLR GND. I need some help here in order to make this circuit work in this odd scenario. Can someone please give me any hint?

Thank you so much.

Image


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PostPosted: 14 Nov 2014, 18:52 
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Joined: 26 Oct 2012, 21:00
Posts: 203
Location: ontario canada
ground is democratic but i believe you already know that.
i'd still like to know what console this came from it would make determining if what your outlining is indeed an issue


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PostPosted: 15 Nov 2014, 11:21 
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Joined: 26 Oct 2012, 21:00
Posts: 203
Location: ontario canada
" so they carry the supply voltage (24V DC) to the microphone XLR GND."
this statement shows me where your thinking is flawed - the preamp has a (-) NEGATIVE supply with a positive gnd, sorry i'm not a teacher perhaps there is a better way to explain it.

by your way of thinking +/- (bipolar supplies shouldn't work because your linking grounds that are opposite polarities) i guess positive and negative voltages can't share a ground....


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