The TELEFUNKEN ELA M 251 amplifier circuit was originally built to satisfy the standardized requirements of the German and Austrian national broadcast systems after World War II. Utilizing a TELEFUNKEN AC701 vacuum tube, a CK12 capsule provided by AKG Acoustics GmbH, and a Haufe made T14:1 ratio output transformer, the TELEFUNKEN Elektroakustik ELA M 251 has achieved legendary stature in the modern recording industry. It is sold here in a matched stereo pairing.
Developed specifically for microphone applications, the AC701 is a sub-miniature triode vacuum tube that produces a very rich and opulent tone. Built from a glass enclosure, its characteristics include a very low self-noise floor, a low degree of microphonics, and a propensity for an exceptionally long life (so long as the voltages provided by the power supply were correct and stable) which meant far less maintenance and consistent results.
The new TELEFUNKEN ELA M 251 includes an edge terminated, dual backplate CK12 capsule capable of cardioid, omnidirectional, and biirectional polar patterns and a European made Haufe 14:1 ratio output transformer (the same design found in the AKG Acoustics GmbH C-12). Each reissue is 100% true in every detail to the original [the parts are interchangeable with the 50+ year old originals], and will deliver the same sonically opulent response that made the ELA M 251 one of the world's most sought after recording tools.
Each ELA M 251 microphone system comes complete with M950 power supply, M850 25' quad-shielded Accusound ACX-7 tube microphone cable, M750 elastic shock mount, FC50 locking flight case and WB50 wooden microphone box.
In 1947 Neumann GmbH first built the U-47 microphone. From 1947 to 1958 TELEFUNKEN GmbH used their established global distribution network for the products produced by Neumann GmbH, which were sold under the TELEFUNKEN name with a TELEFUNKEN logo badge.
In 1958 when Neumann GmbH notified TELEFUNKEN GmbH that they had decided to not renew their distribution contract, TELEFUNKEN reached out to AKG Acoustics about the possibility of AKG creating a "U-47 like" model for TELEFUNKEN to plug into their global distribution network.
This U-47-esque microphone was to be known as the ELA M 250. Like the U-47 this new microphone featured the pattern selection (cardioid and omni-directional) switch on the head of the microphone. Around 1958 Neumann GmbH also released their U-48 microphone which featured cardioid and "figure 8" pattern selection. The TELEFUNKEN ELA M 251 was an amalgam of the two as it featured 3 pattern (cardioid, figure 8 and omni-directional) selection capability.
The switch housing at the base of the capsule assembly is where the similarity between the Neumann GmbH U-47 / U-48 and the ELA M 250 / 251 microphone series ends.The TELEFUNKEN ELA M 250 / 251 features an edge terminated, dual backplate CK-12 capsule (as found in the AKG Acoustics GmbH C-12). The amplifier was the same circuit found in the C-12 that featured a GE 6072 tube and a Haufe 14:1 ratio output transformer. As previously mentioned, a system that featured a TELEFUNKEN AC-701 tube was also designed to meet the technical specifications of German and Austrian broadcast during the period when these microphones were originally constructed.
While the C-12 accomplished pattern selection with an outboard switching device that was connected to the power supply, the ELA M 250 / 251 eliminated that addition to the system and minimized both the quantity of wires that had to run to the microphone as well as the expense of the external pattern selection box.The design engineers at AKG Acoustics also came up with another very handy feature, which was the capability to minimize the time necessary to accomplish "field repairs" of the microphone. Both the C-12 and U-47 / 48 microphones require a fair bit of knowledge, a steady hand, as well as a couple of screwdrivers to get to the internal workings of the mic.
All that was required to "field repair" the ELA M 251E was the removal of the ring on the bottom of the body and the metal body tube would slide right off (no tools necessary!!). Once the body tube was removed either the capsule or the amplifier could be replaced in under a minute saving precious time when under the gun in a broadcast or orchestral recording environment.
The amplifier in the ELA M 250 / 251 series is housed in a molded plastic enclosure. The capsule is held in place by two metal struts that run up the exterior of the amplifier housing. By implementing this system, either of these critical components could be replaced in seconds and the session could continue while either system element could be sent to the technical shop for "component level repair". This convenience was something the broadcasters of the time found to be a major plus as they had thousands of dollars of musicians sitting around for the live music broadcasts of the day. Any time saved cut down on the expense of the session, and added to the quality of the broadcast.
Unfortunately for TELEFUNKEN GmbH, these field replacement provisions also proved to be a sales impediment outside of the orchestral recording world as the plastic bits employed in these microphones added significant cost to the construction of the microphones.
The added cost made them markedly more expensive at the time than the Neumann GmbH and AKG Acoustics GmbH products, thus the non Government owned facilities of the time did not adopt these systems as readily as TELEFUNKEN GmbH would have liked. It is thought that fewer than 3700 total original ELA M systems were built from 1960 to 1965 when TELEFUNKEN GmbH discontinued sales of the microphone.
Today, prime examples of vintage ELA M 250 / 251 [both "E" and "non E"] microphones have become rare and highly sought after jewels, commanding tens of thousands of dollars on the vintage market. You will find that the TELEFUNKEN Elektroakustik recreations exemplify the best qualities of the best examples of these legendary beasts, and while more expensive than most modern microphones, they are true to the heritage of their 40+ year old brethren.
Today TELEFUNKEN Elektroakustik has brought advancement to this classic system through the development of the CK-13™ capsule. While the CK-13 can be fit to any existing ELA M 250 / 251 system it can also be found in the ELA M 251 T which is available through your favorite reseller via the "custom shop".