CM12se

Common name: Advanced Audio CM12se

Production Status: In production

The CM12se is a large-format condenser tube microphone with a capsule design and tube circuitry based on those of the famous AKG C12. Like the original C12 it is an outstanding choice for vocals and acoustic instruments, including percussion, drums and grand piano, as well as for distant miking. The CM12se features Advanced Audio’s own AK12 capsule, an edge-fed, dual diaphragm capsule skinned with German mylar that has a frequency response matching within ±1.5 dB the response of the AKG CK12 capsule. The capsule in the CM12se is hand tested in our shop. The CM12se’s circuit has been optimised for the 6072a dual triode tube. The unused half of the 6072a is incorporated as a cathode follower, resulting in a much lower output impedance than that of the original circuit. This lower output impedance improves the damping factor and allows the use of a transformer with half the turns-ratio of the original C12. The result is a circuit with at least 6db more headroom than the original circuit with a better low frequency and high frequency response. The CM12se utilises a larger BV18 dual-bobbin transformer with an 8:1 ratio. The larger BV18 transformer can handle 3dB more level then the T14 before distortion and has 3dB less output. When close miking percussive sound sources the CM12se will recover faster from a larger transient signals and drive the microphone preamp with 3dB less level than the CM12 when placed in the same position.
The BV18 transformer is driven through a 2.2-ufd mylar capacitor to take advantage of the ability of both capsule and transformer to respond to frequencies reaching down to 10Hz.  The transformer can deliver +18dBm with less than 1% distortion across the audio spectrum.