Dual Valve Condenser Microphone The SE Electronics Gemini MKII dual valve microphone is SE Electronics' ultimate design. A no holds barred piece of microphone history. It really doesn't get any better than this. The dual valve design of the SE Electronics Gemini MK2 means pure valve warmth from the 12AX7 input valve coupled with a 12AU7 valve on the output stage in place of the traditional transformer. The result is that the Gemini produces an incredibly large detailed and intimate sound reminiscent of the classic valve microphones from decades ago, but with all the top end you'd normally associate with the best solid state mics on the market.