Hi all
This is something I'm just a little curious about.

I use an Apogee Mini-Me for everything. When I use any of my newer mics I never hear any hum. However, with a twenty-five year old AKG C-34, or an eleven year old U87 there is an audible hum unless the Mini-Me is earthed (using an AT4060 pwer supply).

The other mics I use are RODE NT5s, AT4047, AT4060, Oktava valve mic (I think it's called the MKL 5000) and a couple of others that I can't bring ot mind at the moment. The Mini-Me doesn't need to be earthed with these, although the 4060 and Oktava are of course grounded through mains.

Any enlightenment would be very much appreciated.

Thanks
John Stafford