U47 Wiring Question

[Phrazemaster]

Hi, I'm building a U47 clone, and I have a question about basic interpretation of the schematic - how to translate into real-world.

Attached is the U47 schematic. Circled (or ovaled) in red is the ground connections.

Would one interpret this literally - ie, take the lead off C1, attach it to the lead off R2, then to the lead off the can shield,  then the lead off R8, etc, on down to the ground at the binder/tuchel connector...or would one literally have some kind of bus bar to which all the connections are made up/down the mic?

Or, would one actually take a wire from each to a star ground point at the bottom of the mic, meaning literally have 7 wires coming down to a star ground internally at the mic. Lead off C1 to star ground, lead off R2 to star ground, lead off can shield to star ground...

- forgive me I've not had the luxury of a real '47 to open, although I've tried to figure this out from many pix.

I know this newbie eye-rollingly simple for you guys, so sorry for that. But I just don't know how to interpret this correctly.

Thank-you,

Mike

 

[Pip]

Hi, I'm building a U47 clone, and I have a question about basic interpretation of the schematic - how to translate into real-world.

Attached is the U47 schematic. Circled (or ovaled) in red is the ground connections.

Would one interpret this literally - ie, take the lead off C1, attach it to the lead off R2, then to the lead off the can shield,  then the lead off R8, etc, on down to the ground at the binder/tuchel connector...or would one literally have some kind of bus bar to which all the connections are made up/down the mic?

Or, would one actually take a wire from each to a star ground point at the bottom of the mic, meaning literally have 7 wires coming down to a star ground internally at the mic. Lead off C1 to star ground, lead off R2 to star ground, lead off can shield to star ground...

- forgive me I've not had the luxury of a real '47 to open, although I've tried to figure this out from many pix.

I know this newbie eye-rollingly simple for you guys, so sorry for that. But I just don't know how to interpret this correctly.

Thank-you,

Mike

They all need to just reference ground just get them tied to the body of the mic and then make sure the body of the mic is tied to the chassis of the PSU through the cable.

 

[Phrazemaster]

I appreciate that Pip...I'm not clear on your meaning.

I already have a good grounding scheme regarding the shielding/mic body/actual ground, per Andreas Grosser.

What I'm not clear about is this: should I take a separate wire from each grounding point down to the ground lug, creating a star ground for all grounded points? Or can I connect them in series one after the other, the final component touching the ground lug? I don't want to create ground loops within the mic itself - but I have a suspicion this second strategy is what is used. Is that right?

Not having the luxury of taking a real U47 apart, I'm not clear.

Thanks for any clarification,

Mike

 

[MagnetoSound]

If you have a spare pin on the tube socket you can use that to tie the capsule side grounds together, and then take a wire from that to the mic connector. The filter caps and transformer ground can be done similarly at a convenient tag or turret.

 

[Phrazemaster]

Hi Dan, thanks for the insights.

It sounds a bit like a loose star-ground scheme then. Looking at all the pix of the guts of a U47 it's impossible to tell without actually having one to check the connections.

Thanks for your thoughts and expertise. Is this how it was done, then, in the original U47?

Thanks,

Mike the mic...er...gonna mic the Mike

 

[MagnetoSound]

There is only one ground wire running up to the capsule end. It connects from the tag board at the bottom of the mic and goes to the ground pin on the headbasket connector. The ground sides of C1, R2 are tied together on this pin. The VF14M, being a steel tube, has a shield connection on pin 3 of the tube socket and this pin is also connected to the ground pin on the headbasket connector. R3 is connected there.

The transformer is connected to the tag board ground which goes back to the Tuchel connector, together with the wire for the filter cap.

It's pretty much like you see it on the schematic.

 

[Phrazemaster]

Dan, I can't tell you how much I appreciate your perfectly detailed reply! That's absolutely invaluable to me!

Thanks so much, that was a godsend!

I'll post back here again after I've looked more deeply at the innards of my FleA clone body tonight or tomorrow.

Thanks again,

Mike