When I bought some studio gear a year or so ago, my son was delighted to find a vintage Gefell M70 capsule on an otherwise useless HH715 wireless microphone. Curious as we were how this famous capsule with nickle diaphragm would sound, I then wanted to complement the M70 with a MV692 preamp. I was lucky to get one for a reasonable price and we could start recording. On acoustical guitar, we appreciated the sound of this microphone so much that we decided to keep it. And I decided to aquire another two of them for modifications and direct comparison with an unmodified MV692/M70. My plan is to replace the rather crappy PCBA with old-fashioned, noisy electronics by something completely new. And at the same time, make them P48 compatible. I intend to try three different circuits: transformerless, with the stock transformer and with a modern high quality transformer. No clue yet which transformer to choose, though.