Positive ground Phantom Power adapter/psu for schoeps cmc3 pd - help please

Hello,

I bought a schoeps cmc3-pd microphone preamp body, and I need to make an adapter, or a battery pack to provide 12v phantom power with positive ground (negative phantom power).

I found a schematic for a 15v phantom supply (normal polarity, not positive ground), which I have attached to this post below (the schematic is from http://www.new-line.nl/?i=61).

If I wanted to make a power supply for the cmc3pd, would it work simply to use this circuit, reversing the polarity of the batteries and the capacitors? or is it more complicated that?

Many thanks for any help.

Josh

Are you sure it is Phantom, not Simplex?

jwk1 said:

Hello,

I bought a schoeps cmc3-pd microphone preamp body, and I need to make an adapter, or a battery pack to provide 12v phantom power with positive ground (negative phantom power).

I found a schematic for a 15v phantom supply (normal polarity, not positive ground), which I have attached to this post below (the schematic is from http://www.new-line.nl/?i=61).

If I wanted to make a power supply for the cmc3pd, would it work simply to use this circuit, reversing the polarity of the batteries and the capacitors? or is it more complicated that?

Many thanks for any help.

Josh

Click to expand...

Indeed, the PD suffix indicates reverse-polarity 12V phantom with Tuchel connectors.
Basically, you can use the schematic you've found, reverse the polarity of the batteries and the electrolytic capacitors, and you're good to go. You may, however, change the style of batteries. The current draw of the CMC3 is not insignificant, so you may want to get closer to the basic specs, so using 8x1.5V cells is a better option. You may want to use rechargeable cells, in that case you would need to increase their number up to 10.
You may have to fine-tune the value of the phantom-injection resistors. IIRC, the recommended value for 12V is 1.2k. If running on 18V, 2.2k is good. But if you use 12V, you may hace to use lower value resistors.