What Is the History of the ELA M 251?

How Did the ELA M 251 Begin

The history of the ELA M 251 is closely connected to the AKG C 12. AKG had already established itself as a leading microphone manufacturer in Vienna, and its C 12 had become known for its multi-pattern operation, extended frequency response, and open European sound.

In the late 1950s, Telefunken wanted a new high-end studio microphone to succeed the U47 in its catalogue. The company turned to AKG, which adapted the C 12 design into a new microphone for Telefunken distribution.

The result was the ELA M 251, along with the closely related ELA M 250. The ELA M 251 and ELA M 251E were introduced around 1959, although historical sources differ slightly on the exact production dates of the earliest models.

What Does “ELA M 251” Mean?

The model name reflects the microphone’s place in Telefunken’s professional product range. “ELA” referred to electroacoustic equipment, while “M” identified the microphone family.

The ELA M 251 was designed for professional studio recording and used a distinctive metal body, a large head basket, and an external power supply. The microphone became recognisable not only for its sound, but also for its elegant appearance and unusual swivel-mount arrangement.

What Made the ELA M 251 Sound Special?

The ELA M 251’s character came from the interaction of three major components:

• The AKG CK12 capsule
• The tube amplifier circuit
• The Haufe T14 transformer

Together, these elements produced the microphone’s familiar combination of warmth, openness, presence, and high-frequency detail.

The AKG CK12 Capsule

At the centre of the ELA M 251 was the AKG CK12 capsule. The original CK12 was a dual-diaphragm, edge-terminated capsule with a complex multi-chamber construction. It could produce omnidirectional, cardioid, and figure-eight patterns when combined with the appropriate circuit.

The capsule became strongly associated with a particular type of European condenser sound: spacious, airy, detailed, and smooth rather than aggressively bright. It was used in several important microphones, including the AKG C 12, Telefunken ELA M 250, and ELA M 251.

Original brass CK12 capsules were difficult and expensive to manufacture. Later versions and modern reproductions have therefore used different materials and construction methods while attempting to preserve the acoustic behaviour of the original design.

The 6072 Tube

The ELA M 251E used a 6072A vacuum tube. This tube was also associated with the export version of the AKG C 12 and helped provide the microphone’s valve-based amplification and harmonic character.

The tube circuit contributed to the ELA M 251’s gentle compression, smooth transients, and flattering response on vocals and acoustic instruments. As with all tube microphones, the exact sound also depends on the condition and individual characteristics of the tube, capsule, transformer, and supporting circuitry.

The T14 Transformer

The microphone used a Haufe T14 transformer for impedance conversion and signal output. The transformer formed an important part of the complete circuit rather than acting as an interchangeable tonal accessory.

The transformer helped connect the high-impedance tube circuit to a conventional microphone input while contributing to the microphone’s overall headroom, frequency response, and harmonic behaviour.

What Polar Patterns Did the ELA M 251 Offer?

The ELA M 251 was a multi-pattern microphone offering:

• Omnidirectional
• Cardioid
• Figure-eight

This made it useful for a wide range of recording applications, including vocals, acoustic instruments, room recording, and stereo techniques.

The ability to change polar pattern was particularly valuable in professional studios because the same microphone could be adapted to different sources and recording arrangements without changing the entire signal chain.

What Is the Difference Between the ELA M 250 and ELA M 251?

The ELA M 250 and ELA M 251 belong to the same family and share much of the same design heritage. Both are associated with the AKG CK12 capsule, tube circuitry, and T14 transformer family.

The main practical distinction is their pattern switching.  The ELA M 251 has three polar patterns whereas the ELA M250 only has two polar patterns.

Because vintage microphones can vary according to production period, component substitutions, condition, and servicing history, the model name alone does not guarantee that two original examples will sound identical.

Why Did the ELA M 251 Become So Rare?

The original ELA M 251 was produced for only a relatively short period.  The limited production run, the age of surviving microphones, and the difficulty of maintaining original components all contributed to the microphone’s rarity. Original CK12 capsules, transformers, tubes, switches, and connectors can be difficult and expensive to replace.

The polar-pattern selector became a particularly well-known failure point in original examples.

Why Does the ELA M 251 Still Matter in Modern Studios

The ELA M 251 remains important because it represents a successful balance between technical complexity and musical usefulness. Its three polar patterns make it versatile, while its tube circuit and CK12 capsule give it a distinctive sound that many engineers associate with polished vocals, acoustic instruments, strings, and room recording.

Its sound is often described using words such as:

• Open
• Airy
• Smooth
• Present
• Detailed
• Warm
• Spacious

These descriptions are useful generalisations, but they should not be treated as guarantees. The result depends on the individual microphone, the source, the room, the placement, and the rest of the recording chain.

Common Misunderstandings About the ELA M 251

The ELA M 251 Was Designed Entirely by Telefunken: The ELA M 251 was a Telefunken-branded microphone, but it was developed and manufactured by AKG for Telefunken. This makes its history a collaboration between two important European audio companies rather than the work of Telefunken alone.

Every Vintage ELA M 251 Sounds Identical: Vintage microphones can differ because of capsule ageing, tube condition, transformer variation, component replacement, calibration, and servicing history. Two original microphones with the same model designation may not perform identically.

The ELA M 251 Is Just an AKG C 12: The ELA M 251 grew from the C 12 design and shares major components and concepts, including the CK12 capsule and T14 transformer family. However, the ELA M 251 has its own circuit, body, control system, and production history.

Summary: Why Is the ELA M 251 Still Legendary?

The ELA M 251 became legendary because it combined AKG’s CK12 capsule technology with tube amplification, a high-quality transformer, three selectable polar patterns, and a carefully engineered studio-friendly design. Developed by AKG for Telefunken in the late 1950s, it had a relatively short production life but left a lasting mark on vocal and instrument recording. Its combination of openness, warmth, detail, and versatility continues to influence microphone design today.