A loudspeaker

Loudspeaker

A loudspeaker is an electroacoustic transducer that produces sound in response to an electrical audio signal input. Non-electrical loudspeakers were developed as accessories to telephone systems, but electronic amplification by vacuum tube made loudspeakers more generally useful...

 driver that produces the frequency range from approximately 300–5000 hertz

Hertz

The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....

 is known as a mid-range.

Midrange drivers are usually cone types or, less commonly, dome types, or compression horn drivers. The radiating diaphragm of a cone midrange unit is a truncated cone, with a voice coil attached at the neck, along with the spider portion of the suspension, and with the cone surround at the wide end. Cone midranges typically resemble small woofer

Woofer

Woofer is the term commonly used for a loudspeaker driver designed to produce low frequency sounds, typically from around 40 hertz up to about a kilohertz or higher. The name is from the onomatopoeic English word for a dog's bark, "woof"...

s. The most common material used for midrange cones is paper

Paper

Paper is a thin material mainly used for writing upon, printing upon, drawing or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....

, occasionally impregnated and/or surface-treated with polymer

Polymer

A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...

s or resin

Resin

Resin in the most specific use of the term is a hydrocarbon secretion of many plants, particularly coniferous trees. Resins are valued for their chemical properties and associated uses, such as the production of varnishes, adhesives, and food glazing agents; as an important source of raw materials...

s in order to improve vibrational damping. Other midrange cone materials include plastics such as polypropylene

Polypropylene

Polypropylene , also known as polypropene, is a thermoplastic polymer used in a wide variety of applications including packaging, textiles , stationery, plastic parts and reusable containers of various types, laboratory equipment, loudspeakers, automotive components, and polymer banknotes...

 Cobex, or Bextrene, woven Kevlar

Kevlar

Kevlar is the registered trademark for a para-aramid synthetic fiber, related to other aramids such as Nomex and Technora. Developed at DuPont in 1965, this high strength material was first commercially used in the early 1970s as a replacement for steel in racing tires...

, fiberglass, carbon fiber

Carbon fiber

Carbon fiber, alternatively graphite fiber, carbon graphite or CF, is a material consisting of fibers about 5–10 μm in diameter and composed mostly of carbon atoms. The carbon atoms are bonded together in crystals that are more or less aligned parallel to the long axis of the fiber...

, or light metal alloy

Alloy

An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...

s based on aluminium

Aluminium

Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

, magnesium

Magnesium

Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...

, titanium

Titanium

Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....

, or other alloys. The radiating surface of a dome midrange is typically a 90-degree section of a sphere, made from cloth, metal or plastic film, with its suspension and voice coil co-located at the outer edge of the dome. Most professional concert

Concert

A concert is a live performance before an audience. The performance may be by a single musician, sometimes then called a recital, or by a musical ensemble, such as an orchestra, a choir, or a musical band...

 midrange drivers are compression driver

Compression driver

A compression driver is a type of loudspeaker driver which uses the technique of "compression" to achieve high efficiencies. In this context compression refers to the fact that the area of the loudspeaker diaphragm is significantly larger than the aperture through which the sound is radiated....

s coupled to horns

Horn (acoustic)

A horn is a tapered sound guide designed to provide an acoustic impedance match between a sound source and free air. This has the effect of maximizing the efficiency with which sound waves from the particular source are transferred to the air...

. A very few midranges are electrostatic drivers, planar magnetic drivers, or ribbon drivers.

A midrange driver is called upon to handle the most significant part of the audible sound spectrum, the region where the most fundamental

Fundamental frequency

The fundamental frequency, often referred to simply as the fundamental and abbreviated f0, is defined as the lowest frequency of a periodic waveform. In terms of a superposition of sinusoids The fundamental frequency, often referred to simply as the fundamental and abbreviated f0, is defined as the...

s emitted by musical instruments and, most importantly, human voice, lie. This region contains most sounds which are the most familiar to the human ear, and where discrepancies from faithful reproduction are most easily observed. It is therefore paramount that a midrange driver of good quality be capable of low-distortion reproduction.

Most television set

Television set

A television set is a device that combines a tuner, display, and speakers for the purpose of viewing television. Television sets became a popular consumer product after the Second World War, using vacuum tubes and cathode ray tube displays...

s and small radios have only a single midrange driver or two for stereo sound. Since, in the case of television the most important aspect is the talking, it works out well. Since the ear is most sensitive to the middle frequencies produced by a midrange the driver and amplifier can both be low power while still delivering what is perceived to be good sound both in terms of volume and quality.

Installation problems

Midrange drivers are usually used in three way multi driver speaker systems. There are therefore special considerations involved in the acoustic join between the midrange and both the low frequency (woofer

Woofer

Woofer is the term commonly used for a loudspeaker driver designed to produce low frequency sounds, typically from around 40 hertz up to about a kilohertz or higher. The name is from the onomatopoeic English word for a dog's bark, "woof"...

s) and the high frequency drivers (tweeter

Tweeter

A tweeter is a loudspeaker designed to produce high audio frequencies, typically from around 2,000 Hz to 20,000 Hz . Some tweeters can manage response up to 65 kHz...

s). The nature of the drivers on both sides of the midrange, and the midrange itself affect the selection of crossover frequency and slope. Nearly all crossovers are passive circuits, designed to match the characteristics of the drivers and their mounting, and are built of capacitors, inductors, and resistors. Active or 'electronic' crossovers are used in some high performance hi-fi speakers, and in professional sound reinforcement system

Sound reinforcement system

A sound reinforcement system is the combination of microphones, signal processors, amplifiers, and loudspeakers that makes live or pre-recorded sounds louder and may also distribute those sounds to a larger or more distant audience...

s.

Placement of the midrange (and tweeter) drivers on the enclosure baffle significantly affects the output of the driver, and the material surrounding the midrange and tweeter drivers on the baffle can produce (or inhibit) reflections of energy from the baffle face, or other items, further influencing the output. Grilles, especially those with structural frames, can further modify the output of the entire speaker system. One of the terms used in design circles to describe some of these diffraction and reflection artifacts is the baffle step effect.

Some manufacturers mount midrange drivers in their own small enclosures, isolating them from the air pressure changes generated by the woofer. These enclosures, especially if they are very small, can increase the Qtc of the midrange driver/enclosure combination, degrading transient response, in exchange for increased output at the lower end of the midrange drivers range.