D-EF47 Tribute To Oliver Archut U47 Build Thread.

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Jul 1, 2022
Awesome. Well when I pull ground from 0v it stops all humming. What does pin 3 have to do with anything? It is not connected to anything in the microphone as far as i understand the schematic and the build. I wonder if this is dangerous to have the mic set up with out a path to earth... I wouldn't want to shock myself or any clients... It does sound great with out the hum though ;P

Ill have to get the optional switch at the shop this week.

Ground to 0v has a 50ohm resistance between the two with the unit on and 4 ohms when the unit is off... so I suppose there is a low impedance path to ground there. Kind of strange...

Ideas about safety?
If it’s any help - I recently built this mic and kept the grounding almost exactly the same as the design, to keep it safe. The only modification I did was insulate the mounting pins of the mic board from the mic body - which was creating a ground loop. Once I did that the ground buzz was gone.

The rest of it didn’t need modification and keeps it safe (still shielded correctly and grounded via a separate cable core)

Proctop has some useful notes in the M49 build as well I think.

Good luck, I love this mic!


Well-known member
Jan 31, 2005
Hi, I am trying ti figure out how to connect the VPT230-110 from Triad, to the www.vintagemicrophonepcbkit.com D-47 PSU Pcb. I can't seem to find the voltage need of the AC inlet?
Should it be series or parallel? (Sorry if this has been answered, I have looked.)


  • Screenshot 2022-12-08 at 17-06-45 Power Transformers - VPT230-110.pdf.png
    Screenshot 2022-12-08 at 17-06-45 Power Transformers - VPT230-110.pdf.png
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