Neumann KM 84 Cardioid Pencil Condenser Microphone
Listen to the sound of a Neumann KM 84 voiced by Rob Holland, Nevada City, CA.
Hear the sound of an acoustic guitar recorded with a Neumann KM 84 courtesy of Henry Spragens at AUDIO IMPROV.
The KM 84 is a small-diaphragm FET condenser with a fixed cardioid pickup pattern. It was the world’s first phantom-powered microphone, built to run on 48v DC. Its design goal was to be as small as possible; the model name “KM” stands for Kleine Mikrofon (“small microphone”). As is the case with all Neumann products, the “i” designation is for microphones that shipped with an XLR output connector for export to the U.S. KM 84 (no i) is electrically the same, but has a DIN-type Tuchel connector for the output.
The model number indicates the powering mechanism (8 equals phantom power) and polar pattern (4 equals cardioid). Although discontinued in 1992, the KM 84 remains a favorite among vintage mic enthusiasts for drum overheads and hi-hat applications.
Neumann’s KM 184 was intended to be a replacement for the KM 84, but the two mics sound sufficiently different that the KM 84 has remained a standard by which modern FET pencil mics are judged. The mic is known for having an exceptionally flat frequency response and its ability to maintain its cardioid pickup pattern across the frequency spectrum.
The resulting frequency response at an angle of ±135° is almost parallel to the 0° on-axis curve. Attenuation at 135° is about 14 dB between 100Hz and 18kHz. As a result, a sound source impinging on the mic anywhere within a three-quarter arc around it will have identical sound quality, even though at different levels. The mic shipped with a “wind and pop screen,” Neumann p/n WNS 21.
The capsule, Neumann model KK 64 and later designated KK 84, utilizes an innovative backplate design that was developed by Neumann in 1964. Whereas most condenser microphone backplates rely on a pattern of through-holes to provide access to the front diaphragm to soundwaves entering from the rear, the so-called “crossed-slit” design incorporates a series of eight intersecting grooves. The grooves allow the sound from the through-holes to be more evenly distributed across the diaphragm. The result is an improvement in polar pattern control and in off-axis frequency response. This “crossed-slit” design is retained in the current Series 180 microphones (including the KM 184).
The condenser mic is different as it varies from the vibrant mics in several ways. It features an incredibly slim diaphragm that is covered on one side with nickel or gold while also being mounted near to the backplate, which is stationary.
Condenser mics tend to generate power via an external power supply, which is described as phantom power. The electric material of the diaphragm can additionally be billed as well as the backplate, utilizing a static voltage. In contrast to vibrant mics, the condenser mic will respond swiftly to transients while also having outstanding sonic features. Condenser mics are popular among professionals who use them in sound support, recording, and measurement.
A wide variety of condenser mics is on the market today, which can make it bothersome to discover the mic that ideally fulfills your individual needs. Depending on how much you’re wanting to invest and the portals which you want to use the condenser mics, there are several choices on offer by applying various attributes.
In the UK, they are often referred to as “capacitor microphones,” and for a good reason too. You might have studied in your physics classes that a capacitor is basically two metal plates in close proximity. The closer the plates are, the higher will be the capacitance.
A condenser capsule is constructed similarly. It consists of a thin membrane in close proximity to the metal plate. The membrane or diaphragm must be electrically conductive, at least on the surface.
Once the sound waves hit the diaphragm, it’ll move back and forth in relation to the solid backplate. In simpler words, the distance between the two plates will change. As a result, the capacitance will change to the rhythm of the sound waves and you would have converted sound into an electrical signal.
The capsule signal is too fragile to be connected to other pieces of gear. The condenser capsule’s output voltage is quite high but it’ll produce almost no current as little energy is stored in the small capacitor. It will require what is usually known as an “impedance converter,” which is a circuit that buffers between the capsule and the outside world. The impedance converter makes the signal more “sturdy” by making far more signal current available.
Condenser mics will therefore require more external power. This would have been highly inconvenient in times past, but today most microphone inputs offers P48 phantom power. It is a Neumann invention that has gone on to become the international standard.
Because of the extremely low mass present, the diaphragm of a condenser mic follows the sound waves more accurately than that of a dynamic mic with a heavy moving coil attached. Condenser mics will therefore offer superior sound quality. Of different microphone types, condensers will come with the wildest frequency response and the best transient response. Moreover, condenser mics will offer higher sensitivity (i.e. output) and lower noise than dynamic microphones.
Keep in mind that such theoretical advantages will only apply to well-constructed specimens (like Neumann’s, of course). A comparatively cheap $99 condenser mic might be noisy and offer lower sound quality than a top-of-the-line moving coil mic.
Condenser mics will require external power for the internal electronics. Some of the early specimens - Neumann has been producing condenser mics since 1928 featured tube electronics that were powered by an external PSU box that is the size of a brick. This ended up becoming inconvenient in numerous ways, especially when many mics were used at the same time as each type required its own PSU box and a dedicated multipin cable.
Once transistor tech took over in the late 60s, Neumann invested in a standardized scheme for powering condenser mics directly from the mixing desk without needing an external PSU box and cables. The P48 phantom power works with 48 volts and are supplied through the usual 3-pin mic cable that doesn’t affect dynamic mics that don’t need external power. Because of this, P48 phantom power would become a world standard.
More recently, tube tech seems to have become popular yet again as a vintage sound alternative. Modern-day tube condenser mics, similar to other ancestors, will require an external power supply just like the ancestors would require an external power supply as tubes will consume more energy than phantom power can provide.
The Neumann KM 84 is a classic small diaphragm condenser microphone and it is the result of a visit to the Norwegian State Television by Neumann engineers in the mid-60s. NST wanted to have smaller, transistor-based mics for a new studio but needed the mics to run off of the central 48V DC power system instead of 12V T-power. Neumann’s engineers devised a plan to power a mic in this way in a major innovation now known as phantom power.
The KM 84 makes use of the KK 64 capsule from the tube-amplified KM 64 mic. This capsule will produce a near-perfect cardioid pattern that maintains frequency response even 130 degrees off-axis while yielding a natural sound without comb-filtered artifacts because of bleeding from other instruments.
The transformer-output amplifier and FET of the KM 84 offer high headroom, which makes the mic widely used as a close mic for drums, especially snares. A -10dB pad is switchable on the body of the microphone for recording, especially hot signal sources. As is the case with almost every Neumann product, the Neumann KM 84 is shipped with a DIN-type Tuchel connector for the output.
KM 84/KMi is essentially the industry standard small diaphragm condenser mic with a cardioid pickup. It is a favorite for classical music recording as it has smooth and faithful reproduction, and it is also popular for its excellent choice for drum overheads, snare, hats, piano, and acoustic guitar.
Following the massive success of their flagship U47 mic, Neumann started to produce small diaphragm condensers (SDCs) in the early 1950s. Several of them have ended up becoming classics in their own right and still continue to be highly valued to this day. Most of the microphones in this series have a model number with the prefix “KM,” which stands for “Kleine Mikrofon.” It means “small microphone” and it indicates the size of the diaphragm and the amplifier body.
The first SDC from Neumann was released back in 1953 and it appropriately enough bore the designation KM 53, which means a tube mic with an AC701, which has an omni pattern capsule. This particular microphone used an aluminum membrane on the capsule instead of PVC or Mylar, which is a material that is proven in the highly accurate measurement mic, the MM2.
The other microphones in the series were the KM 54 and KM 56, both of them having nickel capsules that impart a special tonal quality. For the broadcasting market, Neumann came out with versions of this series that were protected against RF interference. They added a “2” at the head of the model number. Hence the KM 253, 254, and 256 became identical mics to the 5x series with the additions of RF protection and different cable connectors.
The KM 5x microphones were made from 1953 to 1970 while their broadcast cousins were made from 1960 to 1970. A stereo version known as the SM 2 and SM 23 was produced from 1957-1966 using a pair of KK 56 capsules. The KM 6x series was produced from 1964 until 1971 and was similar to the 5x series, except for the capsule membrane, which was plastic rather than metal.
Further development of the 6x series ended up becoming the 7x series, which started the conversion from tube mics to FET microphones. Manufactured from 1966 to 1976, the 7x series was basically the same as the 6x series, except they were solid-state that used 12V “T power.”
The final development of the evolution was the world-famous KM 8x series, upgrading the 7x series to 48V phantom power with an improved capsule. Produced from 1966 to 1992, this amazing series, especially the KM 84 are some of the best-known and best-sounding SDC mics ever made. The KM 84 is absolutely perfect for the nuances of acoustic instruments, so a top-notch studio is lacking without a few of these in the mic locker.
Neumann mics cost a bit more than what most competitors offer; however, are they really expensive? Or is the price justified due to the high quality the Neumann mic offers?
To begin with, not every Neumann mic will cost thousands of dollars/euros. The TLM 103, which was introduced in 1997, was among the first large diaphragm studio mic that is affordable for semi-professionals. In 2009, the slightly smaller TLM 102 made the Neumann sound available even for dedicated hobbyists.
Even less expensive are the Neumann KMS stage mics, which are amazing for home studio use. Neumann’s small diaphragm mics like the KM 184 are quite affordable too, especially when you keep in mind that these are reference-class tools that professionals use daily for the most demanding tasks such as recording orchestras.
As Neumann is a name of world fame, people think of Neumann as a large corporation. However, the simple fact is that the music industry is smaller than, say, the automobile industry, and professional recording is just a small fraction of the music industry. Neumann mics, even the least expensive ones, are not mass-produced on an assembly line; they are essentially handmade.
Condenser mics in general are labor-consuming. Neumann capsules are assembled especially by hand in a state-of-the-art clean room. Each capsule gets tested individually and so are the electronics. Once it is assembled, each mic is tested and measured again, and if it does not conform to its specifications, it doesn’t get sold. A Neumann mic needs to have Neumann quality.
When people compare brands to products from lesser-known brands, they’ll often say “well, you are paying for the name.” While this is true, to an extent it is a good thing too.
The Neumann brand has always been synonymous with quality because its products come with the highest sound and manfacuturing quality. It takes rigorous quality control to keep up Neumann’s distinction as the world’s leading manufacturer of studio mics.
Each new mic that bears the Neumann badge has to be worthy of this proud tradition. The Neumann diamond is more than just a logo, it is a seal of quality.
Neumann mics are certainly not cheap but they’re not expensive either. Neumann’s entry-level mics such as the TLM 102 and 103 and the KMS series is fairly attractively priced, and so is Neumann’s reference class KM 180 series. Their feature-set might be streamlined but they also offer true Neumann sound quality.
Consider the amount of engineering that goes into designing and manufacturing a studio-grade microphone. Isn’t it astounding that you can buy a genuine Neumann at the price of a mid-level guitar?
