A few corrections:
1) The phantom power is usually supplied through a pair of 6.8k resistors in the preamp. Those, in conjunction with the pair of 1-2.2k "summing" resistors in the mic, and the first filter cap after those, form a preeeeeeeeetty "hefty" low-pass filter already.
Using 4.4k (3.4k from the two 6.8k in parallel, in series with a ballpark 2x 2k in parallel) and 10uF over here [ http://sim.okawa-denshi.jp/en/CRtool.php ], gives a low-pass cut-off frequency (-3dB corner) of 3.6Hz, and going down by 6dB/octave from there on. I'm gonna hazard a guess and say that not a lot of ripple's gonna make it to the input
of this oscillator. And that's with VERY conservative values, i think you'll agree. Not that the oscillator would / will care all that much, anyway ;D
And that's even before
the other voltage-dropping resistor (in this case, that 10-50k trimmer) plus the 220uF or however large it is, capacitor
Oh, but isn't the input to the oscillator taken from after
the zener regulator on the mic pcb, anyway? :
That's some extra ripple-"cleaning" right there...
<end of edit>
2) Not quite buying the "wiggle on the oscillator, which will then put out an inconsistent voltage", partially due to the above-mentioned reasons, and partially due to the filter capacitance on the output, coupled with the tiny tiny current it needs to supply.
3) "Carry-over from the Schoeps circuit"? I'm afraid you might've mis-read it - that's assuming we're talking about the original one. The only 1G resistor i see there, is the one from the JFET gate to the wiper of the bias trimpot. The "lone" series resistor that's on the output of the oscillator is a 1M one.
Fair enough. I might go in and jumper the 1G to see if there's a noticeable change in noise.
I should add here that the multiple filters aren't pointless. If there's some ripple in the phantom power, that will appear as a wiggle on the oscillator, which will then put out an inconsistent voltage. Multiple stages can ensure that this is never a problem. I guess a compromise would just be another 1M in place of the 1G or something. The 1G was also a carry-over from the Schoeps circuit itself. Phantom power was probably a lot dirtier in those days.
I don't have a good way to measure noise, but I would expect most of us have clean phantom power.