"mackerr"
"Phil Allison"
> > if you look close you can see 4 wires comming from the part which
picks
> > up
> > sound.
>
> ** There is ONE capsule, shown as number 3 from the back AND front views
&
> given in the parts list as a " Capsule CK12 ".
>
> The capsule design is virtually the same as the C12 and C12 A tube
models
> from the 1950s and 60s.
>
> Only one signal is derived and that comes from the perforated metal disk
> sup****ting the back and front diaphragms.
>
> The diaphragms move as one.
>
Except in the picture it is clear there are 4 wires coming off the
capsule,
** Irrelevant.
The C12A schematic shows that two connections are made to the metal
structure - one for a fixed 60V DC bias and the other for audio signal
extraction.
The other two wires are for the diaphragms, one is grounded and the other
goes to an adjustable 120V DC supply for pattern control.
by changing the electronic relation****p between the two diaphragms via
polarity and level, that they change the mic's pattern.
Whether you call it 1 capsule, or 2 diaphragms, it is 2 balanced signals
that are
manipulated electronically.
** Not correct.
Pattern control is achieved simply by varying the DC bias voltage on one
of
the diaphragms, for the C12A this is:
0V = twin, in phase cardioid operation = omni
60V = one diaphragm inactive* = cardioid
120V = twin, out of phase cardioid operation = figure 8
* since the DC voltage on the structure and the diaphragm are the same.
....... Phil
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