Pickup (music technology)

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Three magnetic pickups on a Peavey Raptor with the pickup configuration of a fat-strat (H-S-S). The bridge (right) pickup is a humbucker and the neck (left) and middle pickups are single coils. Pickup-SSH.jpg
Three magnetic pickups on a Peavey Raptor with the pickup configuration of a fat-strat (H-S-S). The bridge (right) pickup is a humbucker and the neck (left) and middle pickups are single coils.

A pickup is a transducer that captures or senses mechanical vibrations produced by musical instruments, particularly stringed instruments such as the electric guitar, and converts these to an electrical signal that is amplified using an instrument amplifier to produce musical sounds through a loudspeaker in a speaker enclosure. The signal from a pickup can also be recorded directly.

Contents

Most electric guitars and electric basses use magnetic pickups. Acoustic guitars, upright basses and fiddles often use a piezoelectric pickup.

Magnetic pickups

A typical magnetic pickup is a transducer (specifically a variable reluctance sensor) that consists of one or more permanent magnets (usually alnico or ferrite) wrapped with a coil of several thousand turns of fine enameled copper wire. The magnet creates a magnetic field which is focused by the pickup's pole piece or pieces. [1] The permanent magnet in the pickup magnetizes the guitar string above it. This causes the string to generate a magnetic field which is in alignment with that of the permanent magnet. When the string is plucked, the magnetic field around it moves up and down with the string. This moving magnetic field induces a current in the coil of the pickup as described by Faraday's law of induction. [2] Typical output might be 100–300 millivolts.

The pickup is connected with a patch cable to an amplifier, which amplifies the signal to a sufficient magnitude of power to drive a loudspeaker (which might require tens of volts). A pickup can also be connected to recording equipment via a patch cable.

The pickup is most often mounted on the body of the instrument, but can be attached to the bridge, neck or pickguard. The pickups vary in power, and they vary in style. Some pickups can be single coil, while other pickups can be double coil humbuckers. The pickup is one of the most important aspect to distinguishing a guitar's sound. Most guitar models have a distinction in pickups, which act as a new selling point for guitar companies.

Construction

Split pole pickups, Fender Jazz Bass Splitpoles.jpg
Split pole pickups, Fender Jazz Bass

Pickups have magnetic polepieces (one or two for each string, with the notable exceptions of rail and lipstick tube pickups), approximately centered on each string. (The standard pickups on the Fender Jazz Bass and Precision Bass have two polepieces per string, to either side of each string.)

On most guitars, the strings are not fully parallel: they converge at the nut and diverge at the bridge. Thus, bridge, neck and middle pickups usually have different polepiece spacings on the same guitar.

There are several standards on pickup sizes and string spacing between the poles. Spacing is measured either as a distance between 1st to 6th polepieces' centers (this is also called "E-to-E" spacing), or as a distance between adjacent polepieces' centers.

1st-to-6thAdjacent
Standard spacing
(Vintage Gibson guitars)
1.90"
48 mm
0.380"
9.6 mm
F-spacing
(Most Fender guitars, modern Gibson, Floyd Rose bridges)
2.01"
51 mm
0.402"
10.2 mm
Very close to bridge, extra pickup
(Roland GK series hexaphonic)
2.060"
52.3 mm
0.412"
10.5 mm
Telecaster spacing
(Fender Telecaster guitars)
2.165"
55 mm
0.433"
11 mm
Steinberger Spirit GT-Pro spacing
(may be typical for other Steinberger guitars)
2.362"
60 mm
0.3937"
10 mm

Output

Some high-output pickups employ very strong magnets, thus creating more flux and thereby more output. This can be detrimental to the final sound because the magnet's pull on the strings (called string capture [3] ) can cause problems with intonation as well as damp the strings and reduce sustain.

Other high-output pickups have more turns of wire to increase the voltage generated by the string's movement. However, this also increases the pickup's output resistance/impedance, which can affect high frequencies if the pickup is not isolated by a buffer amplifier or a DI unit.

Pickup sound

Single coil pickups, Fender Stratocaster (1963) Pickups.jpg
Single coil pickups, Fender Stratocaster (1963)

The turns of wire in proximity to each other have an equivalent self-capacitance that, when added to any cable capacitance present, resonates with the inductance of the winding. This resonance can accentuate certain frequencies, giving the pickup a characteristic tonal quality. The more turns of wire in the winding, the higher the output voltage but the lower this resonance frequency.

The arrangement of parasitic resistances and capacitances in the guitar, cable, and amplifier input, combined with the inductive source impedance inherent in this type of transducer forms a resistively-damped second-order low-pass filter, producing a non-linearity effect not found in piezoelectric or optical transducers. Pickups are usually designed to feed a high input impedance, typically a megohm or more, and a low-impedance load increases attenuation of higher frequencies. Typical maximum frequency of a single-coil pickup is around 5 kHz, with the highest note on a typical guitar fretboard having a fundamental frequency of 1.17 kHz.

Humbuckers

PRS's Dragon humbucker PRS Dragon Treble.jpg
PRS's Dragon humbucker

Single-coil pickups act like a directional antenna and are prone to pick up mains hum—nuisance alternating current electromagnetic interference from electrical power cables, power transformers, fluorescent light ballasts, video monitors or televisions—along with the musical signal. Mains hum consists of a fundamental signal at a nominal 50 or 60 Hz, depending on local current frequency, and usually some harmonic content.

To overcome this, the humbucking pickup was invented by Joseph Raymond "Ray" Butts (for Gretsch), while Seth Lover also worked on one for Gibson. [4] Who developed it first is a matter of some debate, but Butts was awarded the first patent ( U.S. Patent 2,892,371 ) and Lover came next ( U.S. Patent 2,896,491 ).

A humbucking pickup is composed of two coils, with each coil wound reverse to the other. Each set of six magnetic poles is also opposite in polarity. Since ambient hum from electrical devices reaches the coils as common-mode noise, it induces an equal voltage in each coil, but 180 degrees out of phase between the two voltages. These effectively cancel each other, while the signal from the guitar string is doubled.

When wired in series, as is most common, the overall inductance of the pickup is increased, which lowers its resonance frequency and attenuates the higher frequencies, giving a less trebly tone (i.e., "fatter") than either of the two component single-coil pickups would give alone.

An alternative wiring places the coils in buck parallel, which has a more neutral effect on resonant frequency. This pickup wiring is rare, [5] as guitarists have come to expect that humbucking pickups 'have a sound', and are not so neutral. On fine jazz guitars, the parallel wiring produces significantly cleaner sound, [5] as the lowered source impedance drives capacitive cable with lower high frequency attenuation.

A side-by-side humbucking pickup senses a wider section of each string than a single-coil pickup. [6] By picking up a larger portion of the vibrating string, more lower harmonics are present in the signal produced by the pickup in relation to high harmonics, resulting in a "fatter" tone. Humbucking pickups in the narrow form factor of a single coil, designed to replace single-coil pickups, have the narrower aperture resembling that of a single coil pickup. Some models of these single-coil-replacement humbuckers produce more authentic resemblances to classic single-coil tones than full-size humbucking pickups of a similar inductance.

Notation

Most electric guitars have two or three magnetic pickups. A combination of pickups is called a pickup configuration, usually notated by writing out the pickup types in order from bridge pickup through mid pickup(s) to neck pickup, using “S” for single-coil and “H” for humbucker. Typically the bridge pickup is known as the lead pickup, and the neck pickup is known as the rhythm pickup. [7]

Common pickup configurations include:

Less frequently found configurations are:

Examples of rare configurations that only a few particular models use include:

Piezoelectric pickups

Sensors

Piezoelectric pickup1.jpg
Piezoelectric pickup on a classical acoustic guitar
Peterman dual pickup.jpg
Dual pickup by Peterman in Australia
Piezo violin bridge.jpg
Piezoelectric violin bridge pickup

The piezoelectric pickup contains a piezo crystal, which converts the vibrations directly to a changing voltage.

Many semi-acoustic and acoustic guitars, and some electric guitars and basses, have been fitted with piezoelectric pickups instead of, or in addition to, magnetic pickups. These have a very different sound, and also have the advantage of not picking up any other magnetic fields, such as mains hum and feedback from monitoring loops. In hybrid guitars, this system allows switching between magnetic pickup and piezo sounds, or simultaneously blending the output. Solid bodied guitars with only a piezo pickup are known as silent guitars, which are usually used for practicing by acoustic guitarists. Piezo pickups can also be built into electric guitar bridges for conversion of existing instruments.

Most pickups for bowed string instruments, such as cello, violin, and double bass, are piezoelectric. These may be inlaid into the bridge, laid between the bridge feet and the top of the instrument, or, less frequently, wedged under a wing of the bridge. Some pickups are fastened to the top of the instrument with removable putty.

Preamps

Piezoelectric pickups have a very high output impedance and appear as a capacitance in series with a voltage source. They therefore often have an instrument-mounted buffer amplifier fitted to maximize frequency response.

The piezo pickup gives a very wide frequency range output compared to the magnetic types and can give large amplitude signals from the strings. For this reason, the buffer amplifier is often powered from relatively high voltage rails (about ±9 V) to avoid distortion due to clipping. A less linear preamp (like a single-FET amplifier) might be preferable due to softer clipping characteristics. [8] Such an amplifier starts to distort sooner, which makes the distortion less "buzzy" and less audible than a more linear, but less forgiving op-amp.[ citation needed ] However, at least one study [9] indicates that most people cannot tell the difference between FET and op-amp circuits in blind listening comparisons of electric instrument preamps, which correlates with results of formal studies of other types of audio devices. Sometimes, piezoelectric pickups are used in conjunction with magnetic types to give a wider range of available sounds.

For early pickup devices using the piezoelectric effect, see phonograph.

Other transducers

Some pickup products are installed and used similarly to piezoelectric pickups, but use different underlying technology, for instance electret [10] or condenser microphone technology. [11]

Double systems pickups

There are basically four principles used to convert sound into an alternating current, each with their pros and cons:

  1. A microphone registers the vibrations of the air caused by the instrument. In general this technique guarantees a good sound quality, but with two limitations: feedback and crosstalk.
  2. Contact pickups register the vibrations of the instrument itself. They have the advantage of producing little feedback and no crosstalk at all. In spite of their lesser sound quality and thanks to their low price, contact pickups (and especially the piezoelectric pickup) have become the most popular transducer.
  3. Magnetic pickups. Magnetic pickups, as applied in electric guitars, register the vibrations of nickel or steel strings in a magnetic field. They have the advantage that they can be connected directly to an (electric guitar) amplifier, but in combination with a steel-string acoustic guitar the sound tends to be electric. This is why acoustic guitarists typically choose a piezoelectric pickup, built in microphone, or both.
  4. Electrostatic pickups. Another way is to use the changing capacitance between the string and a pickup plate. These electronic pickups produce much higher dynamics than conventional pickups, so the difference between a soft and a loud pick strike is more pronounced than with other types of pickups.

An amplification system with two transducers combines the qualities of both. A combination of a microphone and a piezoelectric pickup typically produces better sound quality and less sensitivity to feedback, as compared to single transducers. However, this is not always the case. A less frequently used combination is a piezoelectric and a magnetic pickup. This combination can work well for a solid sound with dynamics and expression. Examples of a double system amplifier are the Highlander iP-2, the Verweij VAMP or the LR Baggs dual source and the D-TAR Multisource. [12]

Multi-transducer pickups

Hexaphonic pickups (also called divided pickups and polyphonic pickups) have a separate output for each string (Hexaphonic assumes six strings, as on a guitar). This allows for separate processing and amplification for each string. It also allows a converter to sense the pitch coming from individual string signals for producing note commands, typically according to the MIDI (musical instrument digital interface) protocol. A hexaphonic pickup and a converter are usually components of a guitar/synthesizer.

Such pickups are uncommon (compared to normal ones), and only a few notable models exist, like the piezoelectric pickups on the Moog Guitar. Hexaphonic pickups can be either magnetic or piezoelectric or based on the condensor principle like electronicpickups

Optical

Optical pickups are a fairly recent development that work by sensing the interruption of a light beam by a vibrating string. The light source is usually an LED, and the detector is a photodiode or phototransistor. [13] These pickups are completely resistant to magnetic or electric interference and also have a very broad and flat frequency response, unlike magnetic pickups.

Optical pickup guitars were first shown at the 1969 NAMM in Chicago, by Ron Hoag. [14]

In 2000, Christopher Willcox, founder of LightWave Systems, unveiled a new beta technology for an optical pickup system using infrared light. In May 2001, LightWave Systems released their second generation pickup, dubbed the "S2." [15]

Active and passive pickups

EMG 81 and EMG 85: a pair of popular active pickups EMG 81 & 85 pickups.JPG
EMG 81 and EMG 85: a pair of popular active pickups

Pickups can be either active or passive. Pickups, apart from optical types, are inherently passive transducers. "Passive" pickups are usually wire-wound around a magnet, and are the most common type used. They can generate electric potential without need for external power, though their output is relatively low, and the harmonic content of output depends greatly on the winding.

Seymour Duncan AHB-1 Blackouts Framus Panthera 7 with Seymour Duncan.jpg
Seymour Duncan AHB-1 Blackouts

"Active" pickups incorporate electronic circuitry to modify the signal. Active circuits are able to filter, attenuate or boost the signal from the pickup. The main disadvantage of an active system is requirement of a battery power source to operate the preamp circuitry. Batteries limit circuit design and functionality, in addition to being inconvenient to the musician. The circuitry may be as simple as a single transistor, or up to several operational amplifiers configured as active filters, active EQ and other sound-shaping features. The op amps used must be of a low-power design to optimize battery life, a design restriction that limits the dynamic range of the circuit. The active circuitry may contain audio filters, which reduce the dynamic range and mildly distort certain ranges. High-output active pickup systems also have an effect on an amplifier's input circuit.

Stereo and multiple pickups with individual outputs

Rickenbacker was the first manufacturer to market stereo instruments (guitars and basses). Their proprietary "Ric-O-Sound" circuitry has two separate output jacks, allowing the musician to send each pickup to its own audio chain (effects device, amplifier, mix console input).

Teisco produced a guitar with a stereo option.[ citation needed ] Teisco divided the two sections in the upper three strings and the lower three strings for each individual output.

The Gittler guitar was an experimental guitar[ when defined as? ] with six pickups, one for each string.

Gibson created the HD.6X Pro guitar that captures a separate signal for each individual string and sends them to an onboard analog/digital converter, then out of the guitar via Ethernet cable.

See also

Notes

  1. Lawing, A Scott. "How Does a Pickup Really Work?". Lawing Musical Products. Dr A. Scott Lawing. Retrieved 2 January 2019.
  2. "Guitar Pickup - MagLab". nationalmaglab.org. Retrieved 2 January 2019.
  3. Mottola, R.M. (1 January 2020). Mottola's Cyclopedic Dictionary of Lutherie Terms. LiutaioMottola.com. p. 157. ISBN   978-1-7341256-0-3.
  4. Wheeler. p.214
  5. 1 2 humbucker
  6. Tillman, Donald (2002).
  7. "Gibson Pickups: A Guide to These Epic Game Changers".
  8. Discrete FET Guitar Preamp
  9. Mottola, R.M. (2003). "A Listening Evaluation of Discrete vs Integrated Circuit Audio Preamplifiers in Stringed Musical Instruments". Journal of Musical Instrument Technology (23).
  10. B-Band electret pickup
  11. Schertler Bluestick
  12. http://www.amplifyingacoustics.nl/page/about-the-amplification
  13. "LightWave Systems | Technology". Archived from the original on 25 August 2012. Retrieved 13 September 2012.
  14. Wallace, Joe (2006-12-11). "Light Speed Guitars: The Story Of Ron Hoag And His Optical Guitar Pickup". Gearwire. Archived from the original on 2009-05-01. Retrieved 2009-06-09.
  15. "About | LightWave Systems" . Retrieved 2012-09-13.

Related Research Articles

Electric guitar Electrical string instrument

An electric guitar is a guitar that requires external amplification in order to be heard at typical performance volumes, unlike a standard acoustic guitar. It uses one or more pickups to convert the vibration of its strings into electrical signals, which ultimately are reproduced as sound by loudspeakers. The sound is sometimes shaped or electronically altered to achieve different timbres or tonal qualities from that of an acoustic guitar. Often, this is done through the use of effects such as reverb, distortion and "overdrive"; the latter is considered to be a key element of electric blues guitar music and rock guitar playing.

Guitar Fretted string instrument

The guitar is a fretted musical instrument that typically has six strings. It is held flat against the player's body and played by strumming or plucking the strings with the dominant hand, while simultaneously pressing selected strings against frets with the fingers of the opposite hand. A plectrum or individual finger picks may be used to strike the strings. The sound of the guitar is projected either acoustically, by means of a resonant chamber on the instrument, or amplified by an electronic pickup and an amplifier.

Humbucker Electric guitar pickup

A humbucking pickup, humbucker, or double coil, is a type of guitar pickup that uses two coils to cancel out the interference picked up by coil pickups caused by electromagnetic interference, particularly mains hum. Most pickups use magnets to produce a magnetic field around the strings, and induce an electrical current in the surrounding coils as the strings vibrate. Humbuckers work by pairing a coil that has the north poles of its magnets oriented "up" with another coil right next to it with the south pole of its magnets oriented up. By connecting the coils together out of phase, the interference is significantly reduced via phase cancellation: the string signals from both coils add up instead of canceling, because the magnets are placed in opposite polarity. The coils can be connected in series or in parallel in order to achieve this hum-cancellation effect, although it is much more common for the coils of a humbucker pickup to be connected in series. In addition to electric guitar pickups, humbucking coils are sometimes used in dynamic microphones to cancel electromagnetic hum.

Gibson ES-150

The Gibson Guitar Corporation's ES-150 guitar is generally recognized as the world's first commercially successful Spanish-style electric guitar. The ES stands for Electric Spanish, and Gibson designated it "150" because they priced it at around $150. The particular sound of the instrument came from a combination of the specific bar-style pickup and its placement, and the guitar's overall construction. It became famous due in large part to its endorsement by notable guitar players including Charlie Christian. After Gibson introduced it in 1936, it immediately became popular in jazz orchestras. Unlike the usual acoustic guitars in jazz bands of the period, it was loud enough to take a more prominent position in ensembles. Gibson produced the guitar with minor variations until 1940, when the ES-150 designation denoted a model with a different construction and pickup.

Electric violin

An electric violin is a violin equipped with an electronic output of its sound. The term most properly refers to an instrument intentionally made to be electrified with built-in pickups, usually with a solid body. It can also refer to a violin fitted with an electric pickup of some type, although "amplified violin" or "electro-acoustic violin" are more accurate in that case.

Single coil guitar pickup

A single coil pickup is a type of magnetic transducer, or pickup, for the electric guitar and the electric bass. It electromagnetically converts the vibration of the strings to an electric signal. Single coil pickups are one of the two most popular designs, along with dual-coil or "humbucking" pickups.

Seth E. Lover was a designer of amplifiers and musical instrument electronics and effects. He is most famous for developing the Gibson humbucker or hum-cancelling electric stringed instrument pickup, most often used on the electric guitar.

Rowe Industries Musical artist

Harold "Harry" DeArmond was an industrial designer of electrical components. He is credited with developing the first commercially available detachable guitar pickup. DeArmond established a working relationship with Horace "Bud" Rowe, whose Rowe Industries subsequently manufactured and developed pickups and other music-related devices into the 1980s.

EMG, Inc.

EMG, Inc. is the current legal name of a company based in Santa Rosa, California that manufactures guitar pickups and EQ accessories. Among guitar and bass accessories, the company sells active humbucker pickups, such as the EMG 81, the EMG 85, the EMG 60, and the EMG 89. They also produce passive pickups such as the EMG-HZ Series, which include SRO-OC1's and SC Sets. There is also a series geared towards a more traditional and passive sound known as the X series.

Fender Telecaster Deluxe

The Fender Telecaster Deluxe is a solid-body electric guitar originally produced from 1972 to 1981, and re-issued by Fender multiple times starting in 2004.

Mains hum, electric hum, cycle hum, or power line hum is a sound associated with alternating current which is twice the frequency of the mains electricity. The fundamental frequency of this sound is usually double that of fundamental 50/60 Hz, i.e. 100/120 Hz, depending on the local power-line frequency. The sound often has heavy harmonic content above 50/60 Hz. Because of the presence of mains current in mains-powered audio equipment as well as ubiquitous AC electromagnetic fields from nearby appliances and wiring, 50/60 Hz electrical noise can get into audio systems, and is heard as mains hum from their speakers. Mains hum may also be heard coming from powerful electric power grid equipment such as utility transformers, caused by mechanical vibrations induced by magnetostriction in magnetic core. Onboard aircraft the frequency heard is often higher pitched, due to the use of 400 Hz AC power in these settings because 400 Hz transformers are much smaller and lighter.

P-90

The P-90 is a single coil electric guitar pickup produced by Gibson since 1946. Gibson is still producing P-90s, and there are outside companies that manufacture replacement versions. Compared to other single coil designs, such as the ubiquitous Fender single coil, the bobbin for a P-90 is wider but shorter. The Fender style single coil is wound in a taller bobbin but the wires are closer to the individual poles. This makes the P-90 produce a different type of tone, somewhat warmer with less edge and brightness. As with other single-coil pickups, the P-90 is subject to mains hum unless some form of hum cancelling is used.

Charge amplifier

A charge amplifier is an electronic current integrator that produces a voltage output proportional to the integrated value of the input current, or the total charge injected.

Fender Telecaster Custom

Fender Telecaster Custom is a model of electric guitar made by Fender.

The Lace Sensor is a guitar pickup designed by Don Lace and manufactured by AGI since 1985.

Electric guitar design is a type of industrial design where the looks and efficiency of the shape as well as the acoustical aspects of the guitar are important factors. In the past many guitars have been designed with various odd shapes as well as very practical and convenient solutions to improve the usability of the object.

Parker Fly

The Parker Fly was a model of electric guitar built by Parker Guitars. It was designed by Ken Parker and Larry Fishman, and first produced in 1993. The Fly is unique among electric guitars in the way it uses composite materials. It is notable for its light weight and resonance. It was also one of the first electric guitars to combine traditional magnetic pickups with piezoelectric pickups, allowing the guitarist to access both acoustic and electric tones. Production ended in 2016 and the company has not released a new model of any kind since.

Guitar wiring

Guitar wiring refers to the electrical components, and interconnections thereof, inside an electric guitar. It most commonly consists of pickups, potentiometers to adjust volume and tone, a switch to select between different pickups, and the output socket. There may be additional controls for specific functions; the most common of these are described below.

The Fender Telecaster, colloquially known as the Tele, is the world's first commercially successful solid-body electric guitar. Its simple yet effective design and revolutionary sound broke ground and set trends in electric guitar manufacturing and popular music. Introduced for national distribution as the Broadcaster in the autumn of 1950 as a two-pickup version of its sister model, the single-pickup Esquire, the pair were the first guitars of their kind manufactured on a substantial scale. A trademark conflict with a rival manufacturer's led to the guitar being renamed in 1951. Initially, the Broadcaster name was simply cut off of the labels placed on the guitars and later in 1951, the final name of Telecaster was applied to the guitar. The Telecaster quickly became a popular model, and has remained in continuous production since its first incarnation.

Electric bagpipes

Electric or electro-acoustic bagpipes refers to any set of bagpipes designed to use a pickup to detect the mechanical vibrations of the reed or reeds. As with an electric guitar, the detected electrical signal is then routed to an amplifier, and from there to a loudspeaker. Depending on the volume of the amplified sound, the unamplified acoustic sound of the bagpipe will also be heard to some extent alongside it.

References