A
loudspeakerA loudspeaker is an electroacoustic transducer that converts an electrical signal into sound. The speaker pulses in accordance with the variations of an electrical signal and causes sound waves to propagate through a medium such as air or water.Loudspeakers are the most variable elements in a...
driver that produces the frequency range from approximately 300–5000
hertzThe hertz is a unit of frequency. It is defined as the number of complete cycles per second. It is the basic unit of frequency in the International System of Units , and is used worldwide in both general-purpose and scientific contexts...
is known as a
mid-range. They are also called, less commonly, squawkers.
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.
A
loudspeakerA loudspeaker is an electroacoustic transducer that converts an electrical signal into sound. The speaker pulses in accordance with the variations of an electrical signal and causes sound waves to propagate through a medium such as air or water.Loudspeakers are the most variable elements in a...
driver that produces the frequency range from approximately 300–5000
hertzThe hertz is a unit of frequency. It is defined as the number of complete cycles per second. It is the basic unit of frequency in the International System of Units , and is used worldwide in both general-purpose and scientific contexts...
is known as a
mid-range. They are also called, less commonly, squawkers.
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
wooferWoofer 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
paperPaper is thin material mainly used for writing upon, printing upon 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
polymerA polymer is a large molecule composed of repeating structural units typically connected by covalent chemical bonds. While polymer in popular usage suggests plastic, the term actually refers to a large class of natural and synthetic materials with a variety of properties.Due to the extraordinary...
s or
resinResin is a hydrocarbon secretion of many plants, particularly coniferous trees. It is valued for its chemical constituents and uses, such as varnishes and adhesives, as an important source of raw materials for organic synthesis, or for incense and perfume. Fossilized resins are the source of amber...
s in order to improve vibrational damping. Other midrange cone materials include plastics such as
polypropylenePolypropylene or polypropene is a thermoplastic polymer, made by the chemical industry and 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...
Cobex, or Bextrene, woven
KevlarKevlar is the registered trademark for a light, strong para-aramid synthetic fiber, related to other aramids such as Nomex and Technora.Developed at DuPont in 1965 by Stephanie Kwolek it was first commercially used in the early 1970s as a replacement for steel in racing tires...
, fiberglass,
carbon fiberCarbon fiber is a material consisting of extremely thin fibers about 0.005–0.010 mm in diameter and composed mostly of carbon atoms. The carbon atoms are bonded together in microscopic crystals that are more or less aligned parallel to the long axis of the fiber...
, or light metal
alloyAn alloy is a partial or complete solid solution of one or more elements in a metallic matrix. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may be homogeneous in distribution depending on thermal history...
s based on
aluminiumAluminium or aluminum is a silvery white and ductile member of the boron group of chemical elements. It has the symbol Al; its atomic number is 13. It is not soluble in water under normal circumstances....
,
magnesiumMagnesium 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 by mass, although ninth in the Universe as a whole...
,
titaniumTitanium is a chemical element with the symbol Ti and atomic number 22. Sometimes called the “space age metal”, it has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color.Titanium can be alloyed with iron, aluminium, vanadium, molybdenum, among other...
, 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
concertA concert is a live performance, usually of music, before an audience. The music may be performed by a single musician, sometimes then called a recital, or by a musical ensemble, such as an orchestra, a choir, or a musical band. Informal names for a concert include "show" and "gig"...
midrange drivers are
compression driverA 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
hornsA 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 maximising 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
fundamentalThe fundamental tone, often referred to simply as the fundamental and abbreviated f
0 or F
0, is the lowest frequency in a harmonic series....
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 setA television set is a device used to view television broadcasts.-History:...
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 (
wooferWoofer 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 (
tweeterA tweeter is a loudspeaker designed to produce high frequencies, typically from around 2,000 Hz to 20,000 Hz . Some tweeters can manage response up to 45 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 charactristics 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 systemA 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.