Advanced Audio Microphones CM-12

• Manufacturer: Advanced Audio Microphones
• Model: CM-12
• Category: Large diaphragm condenser tube microphones
• Added in our database on: 12/15/2011

Advanced Audio CM12 

The Advanced Audio CM12 is a large-format condenser tube microphone with a capsule design and tube circuitry based on those of the famous AKG C12/ELA M251. Like the original C12/ELA M251 it is an outstanding choice for vocals and acoustic instruments, including percussion, drums and grand piano, as well as for distant miking.

Capsule

The CM12 features Advanced Audio’s own AK12 capsule, an edge-fed, dual diaphragm capsule skinned with German mylar that has a frequency response matching within ±2dB the response of the AKG CK12 capsule.

Circuit

The CM12’s circuit has been optimized 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.

Output

The CM12 utilizes a BV11 dual-bobbin transformer output modeled on those found in Neumann’s M49 and M50 microphones. Wound to the original specs, the smaller-turns-ratio BV11 is easily driven by the optimized low-impedance 6027a circuit, yielding 6db more output level than the original transformers used in the AKG C12 and ELAM 251.  This allows the head amp gain to be further reduced, increasing the total headroom (output level before distortion) by 6dbB.

The BV11 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.

 Specifications:

    Dual diaphragm, dual back-plate, 35mm edge fed AKG type capsule with 6-micron mylar.

    9 selectable pick-up patterns switch from the power supply.

    Class A 6072a tube circuit

    BV11 output transformer

    Frequency response: 15Hz to 20kHz

    Noise: -17dB (A-weighted)

    Impedance: <200 ohms 

    Distortion: 0.5% @ 125dB

    Output: +18dBm @<1% distortion into 1.2K ohms.

    Robust shock mount

    Aluminum road case