How Do Guitar Pickups Work?
Guitar pickups are inductive sensors which consist of a coil enclosed that is permanently around one or more magnetic pole pieces. The most popular and essential guitar pickups usually incorporate this specific architecture, and this includes the conventional Stratocaster pickup.
Moreover, the inductive sensor is made out of magnetic metal is located below the ferromagnetic string. Whenever the ferromagnetic string vibrates the coil usually produces a signal. Once this signal is amplified, the electric guitar produces sound.
Faraday’s Law of Induction best explains the science behind how magnetic pickups work. This law states the changing magnetic field produces an electric field in the nearby wires and this results in the flow of current if the wire is component of a closed circuit.
Therefore, for an electronic guitar, the vibrating steel guitar strings create a vibration within the magnetic field of the magnet and a vibrating current inside the coil.
Electric guitars typically use different types of pickups, that is the humbucker pickups and single-coil pickups which produce different sounds which may either be mellow, hot or smooth.
Single Coil Magnetic Pickups
The guitar’s evolving role as a lead instrument as well as the continuing increase in the size of bands led to the creation of the first guitar pickups back in the 1930s.
These single-coil pickups acted like small antennas, thereby helping guitarists get heard while performing by picking up numerous kinds of electromagnetic interference typically heard as a hum. Single-coil magnetic pickups integrate a design that detects and responds to the guitar string’s sound vibrations which turn into sound when it is amplified.
Therefore, single-coil magnetic pickups usually produce bright sounds and a tone that is usually not well-defined hence its popularity.
Humbucker Magnetic Pickups
Unlike single-coil pickups, humbuckers come with two coils instead of one. Moreover, its coils are coiled in a manner that rejects any interference and noise by making use of phase cancellation.
Consequently, this results in a smoother, deeper and louder sound unlike that produced by single-coil.
However, despite their differences, these two different types of pickups work identically.
How Exactly Does The Ferromagnetic String Produce The Signal?
This is a technical question often asked by individuals who are curious about how the guitar pickups work. To produce a signal, the vibration of the ferromagnetic string causes the pickup’s magnetic field to be “disturbed”.
Consequently, the magnetic permeability of the ferromagnetic string causes the field around the pickup to start vibrating. This then makes the coil to produce a signal due to the changing magnetic field.
It is this pickup perspective that you often see described in websites, books as well as forum posts written by gear heads, guitar players and winders.
Therefore, it is no surprise given the popularity of this outlook that a lot of emphases is placed on the role of the pickup’s magnetic geometry whenever there is a discussion about the pickup performance, tonality and design.
Nevertheless, there also is another standpoint which is more widespread in books discussing pickups as written by engineers and physicists. This perspective is also the one proposed by the National High Magnetic Field Laboratory. According to this viewpoint, the central idea is that the string is a magnet.
Because of this, the pickup’s magnetic field creates a magnetic dipole within the string around the region over the pole piece. The string becomes a flux source whenever it vibrates, and this basically is a magnetic moving around the coil’s vicinity.
Thus, the coil in this particular model merely acts as a receiver of the magnetic flux that is being produced by the moving and magnetized parts of the string.
These are the different mechanics with which signal is generated. In the first explanation, the pickup’s magnetic field is the most crucial element, and the movement of the pickup within its field lines produces the signals.
However, for the second mechanism, the string is a vibrating magnet, therefore, does not need a pickup which creates a magnetic field so long as the string is magnetized.
So which of these two mechanisms is correct? Therefore, we should experiment to confirm which of the two is true. In this experiment, we will use a Zexcoil pickup which incorporates ferromagnetic pole pieces, structural elements and coils, but lacks magnets thereby does not have its own magnetic field.
Subsequently, we suspend this pickup with no magnets over the guitar so that the distance from the strings when the magnetized pickups were installed in the guitar is identical and then switch between them.
After doing this, the magnetic pickup generated a much weaker signal in comparison to the magnetized pickup which had been integrated into the guitar because it is located in an area of reduced magnetic field strength.
Furthermore, the magnetized pickups generate a field that rapidly decreases with increasing distance as it lacks a magnetic pickup that has its own field. Therefore, its only source of signals would be the unstable field lines of the fairly distant magnetized pickup.
The signals produced by these two pickups usually are identical in strength when the string centric model is accurate because they both are equidistant from the magnetic flux source and the vibrating magnetized string.
However, what you think of how pickups work is either somewhat incomplete or wrong. For electric guitars, the pickup function is the essential aspect, and it acts as a receiver of the magnetic flux rather than a magnetic field generator.
Both these electromagnetic occurrences happen in real life and are essential in varying degrees in different scenarios. However, integrating a magnet is the simplest method of magnetizing the string practically.
Therefore, we can now confirm that the function of the magnetic field produced by the pickup and the pole piece’s function as a magnet has been exaggerated.
According to our experiment, the most crucial role of the pole piece as a magnet is magnetizing the string. Additionally, the most vital magnetic field is that associated which is linked to the vibrating string and not the static field related to the pickup.
With this in mind, we can thus safely assume that so long the string is magnetized, we can safely ignore that the pickup has any magnet incorporated in it. Moreover, the most vital function of the pole piece is shaping the tone and not to act as a generator of the magnetic field, and instead as a receiver of the radiated magnetic flux produced by the vibrating string.
Consequently, the significance of the pole piece both as a filter and concentrator of magnetic flux becomes more apparent.
Whereas all this is a lot to digest, this essentially is how guitar pickups work.
How Do Humbucker Pickups And Single-Coil Pickups Sound?
Is there any tonal difference between humbucker pickups and single-coil pickups? Well, yes there is a slight difference as single-coil picks usually produce sounds that are crisper and brighter.
Additionally, when overdriving small tube amplifiers, single-coil pickups can sound gritty plus can sound glassy with this dependent on the playing techniques, effects and type of amp. Because of this sounds, surf and country guitarists prefer single-coil pickups.
Humbucker pickups, on the other hand, produce sounds that thicker, warmer and rounder. Due to the sound they produce, they are particularly popular with metal, heavy rock and jazz players.
Likewise, humbuckers pickups are popular among blue players looking for overdriven tube sounds due to their emphasis on midrange and a wider spectrum of distortion effects.
It now becomes even harder to make any generalization about the characteristics of pickups. This is particularly so because newer and hotter single-coil pickups can now give humbuckers stiff competition when it comes to output.
What type of magnet is found in guitar pickups?
There are numerous kinds of magnets found in guitar pickups. However, ceramic magnets are the most popular pick, and they usually are inexpensive but tend to be weak magnetically and brittle.
The other common types of magnets include;
- Samarium cobalt (robust but expensive)
- Aluminium nickel-cobalt (Alnico) which are inexpensive
- Neodymium boron iron which is the most expensive but the strongest
There are several compromises found in the design of pickups. First, the use of a stronger magnet means that you require fewer turns of wire for particular audio output, and this subsequently means a smaller guitar pickup.
Pickups made from the standard size and stringer magnets usually produce more audio output. Nevertheless, most of these stronger magnets are very expensive hence why most pickups often incorporate the cheap Alnico magnets.
Furthermore, not all electric guitars need a stronger magnet. Pickups usually affect the strings’ vibration because they are ferromagnetic thereby get attracted to the magnet, and this is a negative aspect since the role of pickups is only to sense vibrations, not to alter them.
To experience this, you need to adjust the guitar’s pickup neck until the poles are located close to each other.
Consequently, you will get to see the magnet adversely affecting the strings or necessitating you to change the magnetic field, which would become very concentrated.
For weaker magnets to be usable, they need to have a bigger diameter, and they generate a wider area which is resistant to the movement of strings whenever they are being bent and plucked.