The Advanced Audio CM-12 is an edge fed, dual diaphragm, tube condenser microphone based on the famous AKG C12 and ELAM 251 capsule design and tube circuitry. The CM-12 circuit is optimized for a 6072a dual triode tube. The CM-12 features a 6 micron, edge fed, dual diaphragm capsule that is within + and – 2db of an original AKG C12 capsule response.
The Advanced Audio CM-12SE features a very accurate edge fed, Peluso CEK-12, 1.07” capsule with 6 micron German mylar diaphragms. This capsule has a frequency response within + and - 1 db of the original AKG C12 mylar capsules used in the C12 and Elam 251 tube microphones.
The 6072a circuit in the CM-12 has been optimized by us to yield a much lower output impedance than the original circuit by utilizing the second half of the 6072a as a cathode follower. This produces about 2db more headroom than the original AKG circuit as a plate resistor is not required with the cathode follower circuit. The lower output impedance of the cathode follower stage improves the damping factor producing a faster transient response. This lower output impedance can easily drive the smaller turns-ratio of the BV11 output transformer yielding 3db more output level than the original transformers used in the AKG C12 and ELAM 251.
The BV11 output transformer will deliver +18dbm with less than 1% distortion. The BV11 transformer is coupled with a 1.5ufd mylar capacitor to take advantage of the transformers and capsules response down to 10 hz. The BV11 transformer is a dual bobbin transformer wound to original Telefunken blueprints and was used in the Neumann M49 and M50 circuits.
