Now as to making a "general" box, I don't see the point. All three actives above are priced right. The only advantage I see is for AKG, since we can get a great hyper capsule for a cheap price.
And the bodies you are replacing are the priciest piece in the AKG setup. Neumann, Beyer, etc have bodies that are cheaper then the caps, and as such, there isn't nearly the gain that you get vs AKG.
It may be worthwhile to just get the mics + collettes from Beyerdynamic, etc and run a small battery box + polarization circuit. Perhaps Jon could build one of those? Even if it sold for the same price as the bodies, it would be smaller and lower power.
That's a cost/size ratio that I've looked at a lot. The beyer bodies for the ck9xx series are barely 3.5" or 4". I looked at his tinybox, and it's about the same length as the bodies, but not quite as think, so effectively you are cutting out 1 tinybox worth of space for a custom design.
At this point I'm sitting on the fence. If someone, Jon or otherwise, built a custom 3-wire battery box with an extra +60V polarization voltage in it, and price it at say $200, I would probably hardwire (FET + other parts behind) my CK63 caps and use it.
I have a similar position as well, if someone could build a battery box for the beyers at a low cost (sub $200), I'd pick up one, but I don't gain enough to justify it over keeping the bodies and using a tinybox or some other phantom (12v or 48v) box.
