Neumann M 50 V Tube Condenser Microphone Set  From Neumann

Legendary Design

Developed in close cooperation with Nordwestdeutscher Rundfunk (Northwest German Broadcasting), the M 50 was the counterpart to the no less legendary M 49. While the latter was a high-quality all-purpose microphone for varying acoustic environments, the M 50 was designed as the ultimate pressure transducer microphone for use in concert halls and dedicated recording spaces.

In practice, this meant that the M 50 was mainly used for recording orchestras, e.g. as the main pickup in various spaced omni configurations. In the 1950s, when the record label Decca experimented with stereo miking techniques, various setups, microphones, and pickup patterns were tried. In the end, the Neumann M 50 was selected as the perfect fit for what is now known as the Decca Tree configuration, i.e. three microphones mounted in a triangle with the outer microphones facing outward. To this day, a Decca Tree setup, often extended with additional outriggers, using Neumann M 50 microphones remains the prime choice for experienced engineers in classical music and film scores. The vivid imaging of this setup in combination with the M 50’s outstanding resolution produces unparalleled results. Today, extended versions of this technique are being used for surround and immersive recordings. Of course, the M 50 has also produced excellent results in other applications, e.g. piano recordings or as a spot mic for string sections and soloists. In pop contexts, the M 50 has been used for miking ensembles or brass sections and as a room microphone, e.g. on drums.

Unique Properties

Finally, the legend is available again! The much-anticipated M 50 V is a reissue of the last revision of the 1960s, the M 50 c. Over the years, the M 50 was continuously improved: the originally installed Hiller tube MSC2 was replaced by the Telefunken tube AC701 and then the AC701k. This and other circuit changes improved the signal-to-noise ratio, dynamic range, and immunity to interference. In parallel, a broadcast version, the M 250, was issued with an RF-proof connector.

The M 50 V is a faithful reissue of the historical M 50 microphones produced by Neumann from 1951 to 1971. It uses the same acoustical concept with a small diaphragm omni capsule, flush mounted in a 40 mm acrylic sphere. This design produces a unique polar pattern, which is omnidirectional at lower frequencies and becomes gradually more directional above 1000 Hz. At the same time, the frequency response shows a smooth rise towards higher frequencies, compensating treble loss in the diffuse field and giving the microphone more “reach”. Being a true pressure transducer, the M 50 has a powerful bass response down to subsonic frequencies, without proximity effect. At the same time, its increasing directivity at higher frequencies offers optimal imaging in stereo, surround, and immersive configurations.

Over the production period of the historical M 50, several capsule types were employed, using different membrane materials. The M 50 V uses an improved version of what is considered the most desirable capsule type, the K 53 with an ultra-thin metal diaphragm, famous for its extremely fast and accurate transient response. The K 33 Ti in the M 50 V uses the same capsule acoustics as the coveted K 53 but with a metal diaphragm made of titanium. Being a lightweight yet rigid material, titanium is an ideal material for metal diaphragms, contributing to the outstanding transient response of the M 50 V. Additionally, titanium offers excellent long-term stability. In fact, the entire K 33 Ti capsule including its backplate and housing is made of titanium, which yields ideal matching regarding mechanical and temperature stability. 

The M 50 V uses the same circuit as the M 50 c, but with an even lower noise subminiature tube. This tube has already proven its exquisite sonic qualities in the M 49 V, where it is used in an almost identical circuit. As radio frequency interference has increased dramatically in recent years, due to mobile phone networks and Wi-Fi, the RF-proof connector has been adopted from the M 250. 

The included NM V power supply is designed to automatically provide the optimal heater voltage for both the M 50 V and any historical M 50; it also automatically adapts to the local mains voltage. Since the same NM V power supply is used for the M 49 V, it includes a pattern control, which of course is of no consequence for the M 50 V with its fixed omni capsule. This power supply can also be used for all historical Neumann microphones using a Telefunken AC701 tube.

Additionally, the M 50 V Set includes the iconic yoke mount, whose flexible positioning has contributed to the M 50’s popularity. As an improvement over the historic yoke mount, the new version has been supplemented with elements for mechanical decoupling of the microphone as well as a cable holder to suppress cable-related structure-borne noise. The M 50 V set is delivered in a high-quality case, which, like the entire microphone, is handmade in Germany.

Compatibility with Older M 50 Microphones

The M 50 V is fully compatible with the last historical variant M 50 c. (See “A Brief History of the M 50” below).

For optimal bass extension, the lower corner frequency of the electronic circuit is set to 12 Hz (–3 dB). It may be changed to 30 Hz to suppress subsonic frequencies via an internal switch S4. To avoid damage, the internal switches should not be operated by the user, but only by Neumann Service. 

A Brief History of the M 50

The M 50 is a true legend, having shaped the sound of countless recordings for more than 70 years. Rather than falling behind, improvements in recording technology have progressively unveiled the true capabilities and outstanding resolution of the Neumann M 50.

Its development was initiated by the broadcast sector. The idea was to replace all existing microphones with only two: the M 49, a universal microphone with remote controllable directivity, and the M 50, an exquisite pressure transducer microphone for critical applications in acoustically favorable environments. The first prototypes were developed at Nordwestdeutscher Rundfunk (NWDR) under the direction of Dr. Herbert Großkopf. Neumann produced M 49 and M 50 microphones from 1951 until 1971.

Masterwork in Progress

• Over its 20-year production run, the M 50 went through a number of changes. 
• The earliest version had the K 50 capsule with a gold sputtered PVC membrane and used a tube specially developed for microphone applications by the Hiller company, the MSC2. 
• From about 1954, the M 50 a used the K 53 capsule with a metal diaphragm made of aluminum. 
• From 1954/55 on, the Hiller tube was replaced by a lower noise tube from Telefunken, the AC701, which was specifically developed for microphones and approved by Neumann.
• In 1957, the M 50 b appeared with a new output transformer (BV11) and some circuit changes. This reduced distortion and increased sensitivity. 
• Starting in 1958, an improved low-microphonics version of the Telefunken tube was installed, the AC701k. 
• Around the same time, the diaphragm material of the K 53 changed from aluminum to nickel.
• In 1964, the M 50 c was released, with further circuit changes. By changing the tube operation from "fixed bias" to "self-bias", noise could be reduced again. Many older M 50 and M 50 b microphones were later converted to circuit version c.
• From 1965, the M 50 c was produced using a K 83 capsule with a gold sputtered polyester diaphragm. Later, when K 53 spares were no longer available, the K 83 was also used for repairs of older M 50 microphones.

In parallel, a special broadcast version was produced from 1961 on. The M 250 uses an RF-proof 7-pin Tuchel connector instead of the bayonet connector. Again, there are different revisions:

• The M 250 (without suffix) was produced only from October to November 1961.
• The M 250 b, introduced in November 1961, is technically equivalent to the M 50 b.
• The M 250 c from 1964 on corresponds to the M 50 c.

The M 50 V Compared to Its Predecessors

The M 50 V combines original sonics with improved long-term and temperature stability. 

The M 50 V uses the same circuitry as the last revision, the M 50 c, which offered considerable improvements in noise performance and dynamic range. Only the Telefunken AC701k tube, which is no longer available, has been replaced by an even lower noise type, also in subminiature format. 

Instead of the K 83 capsule found in later M 50 b and c microphones, the M 50 V employs the K 33 Ti, which is a return to the original acoustic design with an ultra-thin metal diaphragm, offering outstanding transient response. Compared to old K 53 capsules, the K 33 Ti offers improved long-term and temperature stability as the entire capsule, including its ultra-thin membrane, is made of titanium.

Since electromagnetic emissions have increased dramatically in recent decades, due to mobile phone networks and Wi-Fi, among other things, the RF-proof connector of the broadcast version M 250 was adopted. The ancient bayonet connector of the M 50, which has not been available for decades anyway, would not have provided sufficient immunity against interference in modern environments.

The M 50 V set includes the newly designed power supply NM V. Since the new, very low-noise subminiature tube requires a somewhat higher heater voltage, the M 50 V should not be operated using historical power supplies. Conversely, however, the NM V can also be used for old M 50 microphones. An automatic function ensures that the optimum heater voltage is always provided for the tube used. In addition, the NM V automatically adapts to the local mains voltage. Nevertheless, it is not a modern switch mode power supply but a conventional linear power supply – for sound reasons!

The M 50 V set is completed by the popular yoke mount. It has always made the M 50 particularly flexible in terms of positioning and, together with the microphone, forms an iconic unit. Compared to the historic yoke mount, the new version has been supplemented with elements for mechanical decoupling of the microphone as well as a cable holder to suppress cable-related structure-borne noise.