Hi Ethan,
I have built the DEF47s a few times:
The pinouts for the 7 pin XLR and 3 pin are different so yes you are correct shield is pin1 for audio (as standard) and pin3 for tube cable (7pin)
You can simply wire the connectors on the PSU as the pinout says - the board has the 7pin connections and 3 pin and routes shield and ground correctly (as well as the rest, audio etc) I have not needed to route the pins 1 & 2 of tube mic directly to XLR 2&3 - leaving these run on the board.
(you can link the ground shield lift permanently on the board as this does not need to be disconnected ever)
The XLR tab is to connect the shield to the connector assembly - you can link this to pin 3 on the 7pin XLRs (which is for shield on the pinout)
Note: Ground and shield are separate lines on the tube mic cable and should be wired as such, you can link them in the connector if you like though.
For the tube mic cable you should have two heavier gauge cables and a copper shield (as well as the other five cables) - these heavier gauge will be for the heater (pin 4) and ground (pin 7 - centre pin on XLR) and the copper shield for the pin 3 shield connection.
I hope this helps,
Silas
Another note: if you have issues with ground noise my experience was to not ground the mic PCB on the rails but at one single point at the connector, this avoids a loop and maintains good safety shield. My ground and shield lines are linked at the mic end - they are also linked at the PCB by default.
Hey Silas,
I very much appreciate you getting back to me . I am pretty new to building these so hopefully you don’t pull your hair out with my questions , as I may ask you to explain this like I’m a kindergartner! Haha
Also to clarify , the connector I attached the picture of is the one that goes in the bottom of the mic body and goes to the mic pcb . So the tab on the connector in the picture is what they call the the cable shield ? Or is the cable shield something different ? So If I understand correctly I would run the cables as follows :
Pin 1 of the connector goes to the A- pad on the mic body pcb
Pin 2 goes to the A+ pad on the mic body pcb
Pin 3 i would run a wire from it to pin 1 and the. Another wire from pin 3 to the tab i circled in red in the pic , this I assume is the cable shield
Pin 4 goes to the H+ Pad on the mic body pcb.
Pin 5 goes to the B+ pad on the mic body pcb.
Pin 6 goes to the Ptrn pad on the mic body pcb .
Pin 7 goes to ground pad on the mic body pcb.
Am I correct on the routing of the pin 3 to that tab on the xlr and also to pin 1? Or is something else the cable shield that I’m not familiar with ?
Also I will attach. A photo of the wire I bought based on what a member in here recommend , hopefully I got the right stuff . I got two colors ( black and red ) in 22 gauge and the rest in 28 gauge. So pin 4 and pin 7 get the thicker gauge wire ? If I understand correctly the wire from pin 3 to that xlr tab should be the thicker wire too? Does the wire from pin3 to pin 1 need to be thicker wire too? Do you think the 22 gauge wire is thick enough?
Thank you for your help and time. I apologize for my noobness/dumbness . I just want to not screw this up! Haha
Thanks again !
Best,
Ethan
