Polarization Voltage - What is it?

[k brown]

Ooo, Ooo - I know, I know!

"Polarization Voltage": The energy released by a lengthy, pointless disagreement on Gearspace or Group DIY (present thread excepted).

 

[Philbo King]

i found this. i couldnt understand if my life depended on it. i can replace the capsule, i can solder in new leads. if there is a voltage discrepancy, and it could be solved with a 1 or 2 components i can do that to. the math behind it though, no clue.View attachment 88006

Increasing R5 should do it. R5 = 3M3 (AKA 3.3 Meg Ohm) should give you about 62.5 V at the capsule. R4 and R5 form a voltage divider, so:
Vcapsule = Vsource (R5 / (R4 + R5))
where V source is -125V.

Note that this part of the circuit is extremely high impedance. So be very careful to thoroughly clean the board after removing the old part AND after installing the new one, with toulene or isopropyl alcohol. Best to wipe it up before drying rather than just letting it evaporate.

 

[MusoGreg70]

Good to know the NTK to K2 is successful. As for the original post…
I did see another, that suggested just swapping a resistor to lower voltage affects the tube voltage too.

 

[Somkereki]

f I may comment: The polarization voltage is the optimal voltage determined by the manufacturer. An average compromise is noise, linearity, sensitivity (and who knows?) based on what aspects. Since I have been repairing and modifying studio condenser microphones for decades, I sometimes deviated from the value recommended by the manufacturer. A very important piece of advice: We filter the polarization voltage with the best possible quality capacitor and the high-value (several 100 MOhm) resistors should also be low-noise! For example, I improved the signal-to-noise ratio of a Neumann UM 57 microphone by 20 dB. An old story: Also UM 57. The microphone was very "crunchy" noisy. Someone replaced the broken polystyrene insulator in the head connector with a turned piece of PVC material and also made the wire from the membrane to the connector with PVC insulation. I turned a new one from polystyrene and replaced the wire with PTFE insulation. Very the result was good. After I replaced the high-value resistors (made by myself - Japanese (metal layer) 0806 size 47 Mohm resistors, the noise decreased even more. This is an operation that requires a lot of patience. I wish everyone a lot of patience and good health to it!