This originates from KH, and his Whitney Houston mic. Here's the quote from an interview with him.
You once told me you did a 414-EB for...
For Whitney Houston, but I ELA M'd it.
Really?
It's really a royal pain to modify because there's so little space. But boy, what a pocket rocket. What a killer microphone.
It's using a...
...real CK12, but then a very simple FET design, with not much circuit redundancy, but just a simple FET design, straight out.
What exactly is the ELA M circuit, as found in the Telefunken ELA M 251?
What the ELA M circuit does, in difference to the C12 (which shares the same capsule, tube and transformer as the ELA M-251), is that it has a direct wire connection between the capsule and input of the impedance converter. Whereas the C12 has a coupling capacitor in between, which is already one level of sound degradation. The way the tube is biased is also different in the ELA M and the C12. So you can adapt the better sounding system, even when you have a FET (solid state amplifier). A FET is nothing else but a silicon triode. It's almost the same thing, sonically. Only when it get really loud does the FET show its ugly face. If you stay within moderate sound pressure levels, it's really, really hard to tell the difference between a FET circuit and a tube circuit, if they are otherwise identical in design. Except, there's no noise in a FET circuit. It has always been the sh*tty implementation of FET circuitry that has given FET microphones a bad rap, notably the U87
So you can basically build a u87, ditch the feedback network, capsule/fet coupling cap, and use (or not) lower value of the high value resistors. You need 60v for capsule polarization and of course a true CK12 capsule which is 90% of elam sound. The rest 10% are in order: Capsule grille, high pass created by the capsule and lower value resistors (the biasing of the tube he mentions), 120pF cap plate to ground, and maybe 1% transformer which shouldn't play a big role here.