Phantom power mic problem

[salty]

I have a 12 year old focusrite saffire audio interface which successfully supplies power to my condenser mic. I have just bought a new mic which doesn't seem to work, although it has now been replaced for the third time, so I don't reckon the mic is the problem. It is an aston stealth which is a dynamic mic which uses 48v phantom power for its built in preamp. An unusual feature, which is what I bought it for. Except it doesn't work at all with the phantom power switched on. I have read somewhere that the input on the power supply should be reading 46 - 52v across pins 1/3 and 2/3. Mine is reading a bit less, about 30v according to my rather old analogue meter, and only between pins 1/3 - not 2/3. But, as I said, it powers the condenser mic ok. Have phantom power standards changed, so that my old interface is out of date? I've tested my XLR cables and tried both channels in the audio interface.

 

[AnalogKid]

It is possible that the interface is supplying DC on one wire only, because that is all a condenser mic needs and its output is not balanced. If you do not have balanced DC on both wires, a dynamic mic element will saturate - the diaphragm will be either pushed all the say out or pulled all the way in.

Some XLR connectors do not explicitly tie pin 1 to the shell. Please post a small table of the connector pin voltages with not mic connected. Show all possible pin combinations.

Try to get at least a partial schematic of the interface showing the circuitry around the input connector. Also, post a datasheet of both mics.

ak