A ribbon microphone, also known as a ribbon velocity microphone, is a type of

microphone A microphone, colloquially called a mic or mike (), is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and publ ...

that uses a thin

aluminum Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It ha ...

duraluminum Duralumin (also called duraluminum, duraluminium, duralum, dural(l)ium, or dural) is a trade name for one of the earliest types of age-hardenable aluminium alloys. The term is a combination of '' Dürener'' and ''aluminium''. Its use as a tr ...

or nanofilm of electrically conductive ribbon placed between the poles of a magnet to produce a voltage by electromagnetic induction. Ribbon microphones are typically bidirectional, meaning that they pick up sounds equally well from either side of the microphone.

Principle of operation

In a moving-coil microphone, the diaphragm is attached to a light movable coil that generates a voltage as it moves back and forth between the poles of a permanent magnet. In ribbon microphones, a light metal ribbon (usually corrugated) is suspended between the poles of a magnet. As the ribbon vibrates, a voltage is induced at right angles to both the ribbon velocity and magnetic field direction and is picked off by contacts at the ends of the ribbon. Ribbon microphones are also called "velocity microphones" because the induced voltage is proportional to the velocity of the ribbon and thus of the air particles in the sound wave, unlike in some other microphones where the voltage is proportional to the displacement of the diaphragm and the air. One important advantage that the ribbon microphone had when it was introduced is that its very lightweight ribbon, which is under very little tension, has a resonant frequency lower than 20 Hz; in contrast to the typical resonant frequency of the diaphragms in contemporary high quality microphones which used other technology. The typical resonant frequency of those microphones is within the range of human hearing. So even the very early commercially available ribbon microphones had excellent frequency response throughout the nominal range of human hearing (20 Hz to 20 kHz for a young adult). The voltage output of older ribbon microphones is typically quite low compared to a dynamic moving coil microphone, and a step-up

transformer A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer' ...

is used to increase the voltage output and increase the

output impedance The output impedance of an electrical network is the measure of the opposition to current flow (impedance), both static ( resistance) and dynamic ( reactance), into the load network being connected that is ''internal'' to the electrical source. The ...

. Modern ribbon microphones do not suffer from this problem due to improved magnets and more efficient transformers and have output levels that can exceed typical stage dynamic microphones. Ribbon microphones were once delicate and expensive, but modern materials make certain present-day ribbon microphones very durable, and so they may be used for loud rock music and stage work. They are prized for their ability to capture high-frequency detail, comparing very favorably with condenser microphones, which can often sound subjectively "aggressive" or "brittle" in the high end of the frequency spectrum. Due to their bidirectional pick-up pattern, ribbon microphones may be used in pairs to produce the

Blumlein Pair Blumlein pair is a stereo recording technique invented by Alan Blumlein for the creation of recordings that, upon replaying through headphones or loudspeakers, recreate the spatial characteristics of the recorded signal. The pair consists of an a ...

recording array. In addition to the standard bidirectional pick-up pattern, ribbon microphones can also be configured to have

cardioid In geometry, a cardioid () is a plane curve traced by a point on the perimeter of a circle that is rolling around a fixed circle of the same radius. It can also be defined as an epicycloid having a single cusp. It is also a type of sinusoidal ...

, hypercardioid, and variable

pattern A pattern is a regularity in the world, in human-made design, or in abstract ideas. As such, the elements of a pattern repeat in a predictable manner. A geometric pattern is a kind of pattern formed of geometric shapes and typically repeated li ...

. As many mixers are equipped with

phantom power Phantom power, in the context of professional audio equipment, is DC electric power transmitted through microphone cables to operate microphones that contain active electronic circuitry. It is best known as a convenient power source for con ...

in order to enable the use of condenser microphones, care should be taken when using condenser and ribbon microphones at the same time. If the ribbon microphone is improperly wired, which is not unheard of with older microphones, this capability can damage some ribbon elements; however, improvements in designs and materials have made those concerns largely inconsequential in modern ribbon microphones.

History

In the early 1920s, Drs.

Walter H. Schottky Walter Hans Schottky (23 July 1886 – 4 March 1976) was a German physicist who played a major early role in developing the theory of electron and ion emission phenomena, invented the screen-grid vacuum tube in 1915 while working at Siemens ...

and Erwin Gerlach co-invented the first ribbon microphone. By turning the ribbon circuit in the opposite direction, they also invented the first ribbon loudspeaker. A few years later, Dr.

Harry F. Olson Harry Ferdinand Olson (December 28, 1901 – April 1, 1982) was a prominent engineer at RCA Victor and a pioneer in the field of 20th century acoustical engineering. Biography Harry F. Olson was born in Mount Pleasant, Iowa, to Swedish immigrant ...

RCA The RCA Corporation was a major American electronics company, which was founded as the Radio Corporation of America in 1919. It was initially a patent trust owned by General Electric (GE), Westinghouse, AT&T Corporation and United Fruit Comp ...

started developing ribbon microphones using field coils and permanent magnets. The RCA Photophone Type PB-31 was commercially manufactured in 1931, greatly impacting the

audio recording Sound recording and reproduction is the electrical, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording t ...

and

broadcasting Broadcasting is the distribution of audio or video content to a dispersed audience via any electronic mass communications medium, but typically one using the electromagnetic spectrum ( radio waves), in a one-to-many model. Broadcasting beg ...

industries.

Condenser microphone A microphone, colloquially called a mic or mike (), is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and public ...

s at the time could not compare to its

frequency response In signal processing and electronics, the frequency response of a system is the quantitative measure of the magnitude and phase of the output as a function of input frequency. The frequency response is widely used in the design and analysis of s ...

. Radio City Music Hall employed PB-31s in 1932. The following year, the 44A came on the scene. Its tone and pattern control helped reduce reverberation. Many RCA ribbon models are still in use and valued by audio engineers. The

BBC-Marconi Type A The BBC-Marconi Type A is a ribbon microphone that was produced by the BBC and Marconi between 1934 and 1959. The microphone has been described as "iconic" and a symbol of the BBC. History In the early 1930s, the BBC became aware of RCA's m ...

was an iconic ribbon microphone produced by the

BBC #REDIRECT BBC #REDIRECT BBC Here i going to introduce about the best teacher of my life b BALAJI sir. He is the precious gift that I got befor 2yrs . How has helped and thought all the concept and made my success in the 10th board exam. ...

...

Principle of operation

History

See also

References