sensitivity control for a microphone

Anyone know what was the first use of the capsule voltage being used as a sensitivity control?

IIRC the TLM150 has a switch for two voltages the early groove tubes microphones might have a control from reading the specs. I have not used a early groove tube microphone or the tlm150 just read the specs

In the groove tubes book I have there are pictures of SP. Did SP have anything to do with the Groove tube microphones?

Was there a control on some of the early german microphones?

I want to get the correct history on this.

> what was the first use of the capsule voltage being used as a sensitivity control?

Probably the first time someone tried to get a condenser mike working.

The voltage really should be as high as possible without fall-in. If you made a mike too hot, adding dummy capacitance is generally the best way to reduce output.

IIRC??? I wish folks would not use texting jargon.
Stephen

Gus,

For some years ago I repair a Grove Tube MD-3 (issue 1996) and I remember this have a "capsule polarization gain control"

From my notes:

Adjustable polarization voltage between +20 to +110 volt.
The gain potentiometer have a strange control behavior, all gain change happen in the minimum end.

--Bo

Stephen,

IIRC - If I Recall Correctly. It's a valuable abbreviation, really.. :grin:

Changing sensitivity by altering polarisation voltage is not a really great idea, as membrane tension also changes with voltage, meaning that your tension won't be optimized most of the time..

Jakob E.

Thanks Bo

Thats a start. Anyone know if SPA microphones had something like this?