Telefunken ELA-M251

Telefunken ELA-M251

Classic Tube Microphone Daily Rate: $100

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The most famous "Elam"  microphones, must be the M250/251 series. Their design was based around the famous "Original" CK12 capsule, but wired differently to that in the C12. As mentioned above, these units were manufactured by AKG and distributed, and therefore badged, by Telefunken. The type number could be suffixed by the letter "E". This means that model was designed for "Export" and uses a different type of valve. The "Standard" M250/251's were designed around the Telefunken AC701k valve, which were only readily available at that time, in central Europe. To take sales of this microphone into other areas of the globe, it was required to design a pre-amp / impedance converter, that was based around a valve that was more readily available in other parts of the world. Therefore, the "E" models used a plug in valve, namely the American 6072, rather then the "Continental" or "European" hard wired Telefunken AC701k. Of course, their performance is quite different.


The electronics of the Ela M250/251 series, are "Standardized" to the valve type used and housed in a large diameter perspex cylinder. This was all part of an idea by AKG's design team, which enables the microphone to be easily dismantled into "Changeable" sections. The idea being that you could dismantle the microphone down to the basic level of "Sections", and replace them without the use of any tools. Quite a novel idea, however, it must have been quite expensive to keep a selection of spare parts (sections) in stock, rather then just single components. This perspex cylinder, encasing the electronics, proved to be very fragile. The screws and there captive nuts, that hold the two halves of the cylinder together, only act as "Crushers" if over tightened. Therefore when changing a valve etc, on these delicate units, take great care not to over tighten the fixing screws. When considering the 250E and 251E, using the 6072 valve, with all the space available, it seems a shame, that a larger audio transformer was not used, such as that used in the early AKG C12, type V2148. This would have given the microphone such a wonderful increase in LF "Dynamics". However, the smaller T14/1 transformer and together with a 0.5uF, coupling capacitor, were used instead. A modification is available, this enables an "Increase" the LF performance of the microphone, which it well deserves.


AKG, which stands for Akustische und Kino-Gerate (Acoustic and Film Equipment) was formed in 1947 in Vienna, Austria. AKG developed the C-12 condenser microphone in 1953 based on a dual backplate/dual-membrane idea patented by Kalusche and Spardock in 1951. The modified version of this idea became the basis for the CK-12 capsule.


AKG was the first to manufacture a split electrode microphone. The original capsule membrane was 10-micron-thick PVC, which was later changed to 9-micron-thin Mylar. The amplifier design was based on the 6072 tube, and the C-24 stereo edition of the mic with two CK-12 capsules utilized this dual triode to its full extent.


The C-12, like the M49, had a remotely controlled pattern selection from omni to bi-directional via the selector switch located in a box between the microphone and the power supply. The C-12 remained in production until 1963. In 1964, the C-12A appeared with a 7586 Nuvistor tube amplifier and a physical shape foreshadowing the design of the 414 Series. In 1959, after the U47 had been withdrawn from Telefunken distribution, Telefunken commissioned AKG to develop a large-diaphragm condenser microphone. This became the ELAM 250.

This design incorporated the CK-12 capsule in a wider body with a thicker wire mesh grille. A two-pattern selector switch (cardioid to omnidirectional) was placed on the microphone. The ELAM 251 added a third bi-directional pattern to the switching arrangement. The "E" designation after the 251 indicates export, incorporating a 6072 tube amplifier. Non-E designations indicate the standard German AC701K tube amplifier.


The immense popularity of the C-12 and ELAM 250/251 microphones has made them the most expensive and highly desirable vintage tube mics on the market today.


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