Capsule base question

[Greenie]

Hi. What could be used instead of metal (steel) in the base of the capsule. I am buildin a U67 and I have to make some adjustments in the capsule base to fit the pcb board. Could it be a turretboard, plastic or other material type?

 

[Khron]

As long as you can make sure the body tube and the headbasket form a continuous shielding shell, i doubt the material the capsule base plate is made of, matters.

 

[soliloqueen]

I have seen some mics use the PCB itself as the plate, even. See TLM103

 

[Greenie]

When building tubeamplifiers, the groundloop is a constant problem. Is it ok if the pcb touches the mic rails a problem?

 

[Khron]

Quite the contrary. In whatever mics i've put together, i've strived to have the groundplaneof the pcb make as much contact with the mounting rails as feasible.

In tube amps, on one hand, far greater currents than in mics are involved. And on the other hand, those don't have the option of having a balanced output to connect to other devices downstream (and thus, if necessary, disconnect the XLR output pin 1 from ground / earth).

 

[Greenie]

Good to hear, groundloops are a menace...

 

[Khron]

My CAD Trion 8000 has a ground-lift switch for the output XLR pin 1, but i'm not sure i've seen that on other power supplies so far. And i don't recall needing to use it yet.