First thing to say: If you are unsure about how the mic works and what the wires are
doing, DON'T RE-WIRE IT. There is a risk that you will damage or destroy the microphone --
or whatever you connect it to! Seek professional help instead -- someone who can dismantle
the mic, understand how it works, and wire it accordingly.
And secondly, DO
NOT APPLY NORMAL PHANTOM POWER TO THIS MIC UNDER ANY CIRCUMSTANCES!
bit of googling suggests that this mic is something of an odity -- it is a high output
DC-biased Capacitor mic, but without an impedance converter in the mic itself!
I've seen posts elsewhere to suggest that it has an unbalanced output (no surprise
there!), and requires a 100V DC bias voltage to activate the capsule -- which would
normally be supplied by the (valve-based) tape recorder.
unbalanced DIN connection has the ground on pin 2 and the signal input to the recorder on
pin 3. That being the case, I'd assume pin 1 would be the DC bias voltage... but you'd
have to check that before any attempt at re-wiring.
Since valve recorders of
the day operate with very high input impedances anyway, I presume the mic relies on that
to avoid leakage currents from the capsule... and the very high bias voltage would also
help bestow the alleged high output.
Either way, this mic won't be at all
happy being connected to a modern (relatively low impedance) preamp input -- or via a
balancing transformer for that matter, and it won't work at all without the appropriate DC
bias voltage correctly applied. Essentially, it will require a bespoke high-impedance
input buffer amp stage and a suitable high voltage, high impednace biasing power supply --
the precise facilities provided by the partnering Grundig valve tape recorder, in
It would, theoretically, be possible to power the mic using a phantom
supply in a vaguely similar way to how many electret mics are powered via phantom, and to
build a high-impednace buffer with a cascode FET stage or similar... but this is not
something I'd like to advise about with a sight-unseen vintage mic on a forum like
I've also read reports that the very largre diaphragm is prone to
cracking... so to be honest it's really probably not woirth your while trying to get this
thing going. Stick it on a shelf as a pretty antique instead!
Technical Editor, Sound On Sound