just checked the file and it shows them as FET based...actualy there were 3 different configurations of fet boards..the orig, then one w/ RF decoupling caps and a drop down R (orig must have been too sensitive), then a third to correct the phase difference from when they switched from electret membrane to back electret technique.
another bit of useless knowledge
peace
jah
The "User Instructions" that came with my CK1X capsules read: "Permanently charged condenser capsule design in well-proven CMS technology." It also has the polar response grids and the technical data for the capsules. If you don't have one already, it may be good info for your file.
I don't see any reference to FET in the booklet, but then again, I don't understand that stuff very well.
Permanetly charged??? No Idea what that means or what cms is as long as you like 'em that's what counts
Permanantly charged is referring to the style of electret condensor.. ie. Permanantly Charged Back Electret. Instead of getting an electrical charge to the microphone capsule with phantom, these electret mics diaphragm's are made from a material that has a permanent electrical charge. You still need a body to act as a preamp and alot of these were run off battery (an example would be the NAK CM300's or the Senn ME). So with the AKG's the active head is permantly charged and the 48v is really only operating the body. I got this info straight from AKG. My understanding from the email that is the way they had to be. Something about the bodies not originally being made to support an active head. I sent along a bunch of questions to them once (My main question was if they still serviced any of the active components, which unfortunately they no longer do). But all P.C. Back electrets arent like the NAK and Senn (mid level mics). They have some very quality ones as well, I found a website which enlightend me to the fact that a bunch of B&K mics were back electret, the Shure KSM32 is also back electret, The Crown CM700, also mics like the AKGC-1000 (which is more at the level of the NAK 300 and the Senn's).