Telefunken M251 (c. 1958)
A rebadged AKG that outgrew its own parent. Collectors still chase it, and still argue about it.
Overview
The Telefunken M251 is not really a Telefunken design. It is an AKG microphone, rebranded for Telefunken's distribution network. The same arrangement put the microphone out under the Siemens banner as the SM 204. Mix (October 2001, p.184) ranks the multipattern Telefunken ELA M251E/250E among the three most sought-after tube condensers ever built, alongside the Neumann U47 and the AKG C-12.
The lineage runs back to the C12. AKG's C12, developed by engineer Konrad Wolf, was the first true multipattern microphone with remote polar control - an external box selecting any of nine patterns - and it was the C12 that Telefunken rebadged as the M251. The capsule in the family is the CK-12, a dual-backplate design invented by two Siemens engineers. It holds consistent on-axis sensitivity as the pattern changes. It paired that backplate with two 10-micron diaphragms, later upgraded to 6-micron Mylar. According to the period documentation, the M251 carries the AC701 tube and covers 40 to 13,000 Hz (±3 dB), with an actual range extending to 15,000 Hz. Sensitivity is quoted at approximately 0.9 millivolts per dyne per square centimeter in omnidirectional mode.
The patterns are where collectors get argumentative. The microphone is documented as offering omni, cardioid, and figure-eight. Period notes flag that the pattern arrangement is not the same as the C12's nine-position remote system, so anyone expecting C12-style remote pattern control should look closely before buying. EQ (June 1997, p.30) dates the release to circa 1958 and puts current market value at $7,500 to $10,000 depending on condition.
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