ELA M 251
Effective June 1, 2017 TELEFUNKEN Elektroakustik has suspended standard production of the AC701 based ELA M 251 microphone. Please note that we will continue to produce our most popular flag ship microphone, the ELA M 251E, which features the more common GE JAN 6072a vacuum tube.
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 ELA M 251 has achieved legendary stature in the modern recording industry.
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.
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. TELEFUNKEN Elektroakustik’s historic recreations of the ELA M 251 exemplify the best qualities of the finest specimens of these legendary beasts, and while more expensive than most modern microphones, they are true to the heritage of their 50+ year old brethren.
History Of The ELA M 251 Circuit Design
Arguably the most beautiful microphones ever produced, the TELEFUNKEN ELA M 250 / 251 was originally sold in two variations: the "ELA M 250E / 251E" version utilized a 6072a tube, while the "ELA M 250 / 251" version contained a TELEFUNKEN AC701 tube. The "no-suffix" microphones were built to satisfy the standardized requirements of the German and Austrian national broadcast systems. While both versions of these microphones have achieved legendary stature in the modern recording industry, the road to achieving this legendary status was far from instantaneous.
In 1947 Neumann GmbH first built the U47 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 "U47 like" model for TELEFUNKEN to plug into their global distribution network.
This U47-esque microphone was to be known as the ELA M 250. Like the U47 this new microphone featured the polar pattern selection (cardioid and omnidirectional) switch on the head of the microphone. Around 1958 Neumann GmbH also released their U48 microphone, which featured cardioid and bidirectional pattern selection. The TELEFUNKEN ELA M 251 was an amalgam of these two microphones as it was capable of switching between all three patterns (cardioid, omnidirectional, and bidirectional).
The switch housing at the base of the capsule assembly is where the similarity between the Neumann GmbH U47/48 and the ELA M 250 / 251 microphone series ends.
While the C12 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 C12 and U47/48 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.
In order to perform a "field repair" of the ELA M 251E, one simply needed to unscrew the base ring from the bottom of the mic 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 during an expensive broadcast or orchestral recording session.
The amplifier in the ELA M 250 / 251 series is housed in a molded plastic enclosure. The capsule and head grill assembly 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 the faulty system element could be sent to the technical shop for in-depth 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. TELEFUNKEN Elektroakustik’s historic recreations of the ELA M 251E exemplify the best qualities of the finest specimens of these legendary beasts, and while more expensive than most modern microphones, they are true to the heritage of their 50+ year old brethren.