Gemini tube studio microphone very low output

[Mick Bailey]

Does anyone have a schematic for the SE Gemini studio condenser mic? Voltages to tubes seems ok and there's a strong output hum when the capsule +v connection on the board is touched, indicating that the preamp is working. There's hardly any vocal output though, which leads me to suspect the capsule or it's polarizing voltage may be the culprit.

The polarizing voltage appears to be very low at 450mv - anyone know what this should be? I was expecting some tens of volts. The capsule connections test fine and its capacitance reads 128pf, but scope shows negligible signal output.

[Mick Bailey]

I've not worked on one of these before and taking another look revealed that the voltage across the capsule can't easily be measured because the series resistor is 1G Ohm. Anyone got any experience of testing/fixing this type of mic? No luck with contacting SE directly.

Basically just a tube preamp and phase splitter - I need to know how to test the rest of it.

[Mick Bailey]

Sorry - just realised I've posted this under the wrong section (again!)