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There are two main types of magnetic pickups:
  • single coil,
  • humbucker.
How a pickup work image
The single coil pickup and humbucker pickup structure

A single coil pickup consists in some thousands of very thin coated wire turns, wrapped around a bobbin made by a number of permanent magnets.

Among the factors that more influence the tone the pickup we find:



All the above strongly affects the sound of the pickups and of the instrument itself.

The bright tone of the single coil pickup comes from two main factors: the single bobbin and the fact that it captures a very small portion of the string's vibration as opposite to the humbucker pickup which, being composed of two adjacent bobbins, captures the string's vibration in a wider area, delivering a wider harmonic content.
Single coil pickups tend to be pretty "noisy" as they act as antennas capturing the 50/60Hz cycle hum especially when computers, monitors, Tv and neon light are present.

Humbucker pickups are no more than two single coil pickups coupled so that the direction of the winding coil is opposite and the polarity of magnet is reversed. This coils structure, also known as RW/RP (reverse wound / reverse polarity) actually allows one coil to cancel the other's noise and also result in a stronger signal.

Wiring the two coils in series doubles the inductance resulting in a fatter tone with dampened highs, capable of driving the preamp section of the modern and old guitar amplifiers.

Wiring the two coils in parallel produces a weaker and brighter tone and is more diffused on basses (Masic Man Stingray).

There are basically two types of humbucker pickups: the classic design with the side by side bobbins and the "stack" humbuckers where the two coils are placed one over the other to maintain a more classic "single coil look". In this kind of humbucker the whole impedance is calibrated by the manufacturer to achieve a brighter tone than usual. This and the fact that it captures a narrower portion of string's vibration allows to replicate the original single coil tone in almost all of its components or to achieve a "fatter" single coil tone.

Typical humbucker pickup mounted on Tuscany Luxor model.

Magnets used for pickups manufacturing lose about 1% of their magnetic charge at the very moment they sense the strings for the first time. In the next first year they lose about another 1,2% of their magnetic power. From then on they only lose 1% every many thousands of years.

Different types of guitar pickups image
Three different types of single coil pickup. 1) Formvar isolated wire 2) Enamel isolated wire (typically dark), 3) ceramic pickup for 7 strings guitars.

The shape and diameter of the magnet itself strongly influences the the way the pickup will sound like. This is due to the different types of magnetic field it will reproduce and how the string will sense it.

Just think to the difference between a Music man large magnet pole and the two small coupled magnets of the Jazz Bass pickups.

On the Fender pickups the strings' vibration is captured by two sided small poles instead than only one. This has made the JB famous for its strings attack.

In the first moment when string is plucked (both with fingers or slap) the vibration is wider and the tone is properly captured by the two distanced poles and this enhances the attack fo the string.

In the following second while string decay, the vibrational pattern is reduced and the string end up stop moving between the two poles rather than exactly over them, so decay is faster. This is why we like to push hard on the JB strings for that "snap" tone and this is why this bass is so favoured for its attack.

Jazz bass poles pickup alignement image
Jazz bass style pickup poles.

This won't happen on pickups with single and larger poles (like on Music Mans for example) or with rails (blade or dual blade) pickups which capture the string's vibration right over from the beginning till the end, delivering a more even tone with no no peaks of any of the string's vibration moments.

Blade or rails pickups need to be radiused following the fretboard shape to evenly capture a balanced strings tone.

A set of Joe Barden pickups with blade rails magnets.

Being actually magnets, pickups tend to "hold" string's vibration thus inhibiting sustain.

Pickups placed too close to the strings (especially the neck one which interacts with them where vibration is wider) not only affect sustain but may also cause tuning and intonation problems.

Pickups may sometime also show some uncontrollable feedback problems. These are due to the winding of the pickups bobbing getting loose and becoming microphonic or sometimes to the pickup vibrating into its metal cover. This problem can be solved by potting the pickups.

A last trick: as the old piano crafters master teach us, the best sounding point to pluck a string is somewhere between 1/5 and 1/6 of its length (approx where the middle Strat pickup is placed).

Plucking the string in this portion of the string reduces the dissonant effect of the seven harmonic.

HINTS AND TIPS

The distance of the pickup from the bridge and from the strings will determine the output volume, tone and performance of the instrument:

  • the nearer the pickup to the bridge the more of the high frequencies and harmonics content will be captured resulting in a brighter tone,
  • the nearer the pickup to the neck the more of the fundamental harmonic content will be captured resulting in a warmer mellower tone,
  • the nearer the strings the more the attack, the volume and the high frequencies we will have and the more the magnet will disturb vibration so less sustain,
  • pickups adjusted too far from the strings will tend to reproduce a mellower tone with less brightness and attack and more sustain but will tend to sound "dead",
  • as high frequencies tend to decay faster, pickups which are placed nearer to the bridge will seem to have less sustain then the ones placed on the neck side,
  • the larger the portion of strings sensed by the pickups (humbuckers) the more accentuated the low end will be,
  • the narrower portion of strings sensed by the pickups (single coil) the brighter the tone will be.

  • � 2010 Galeazzo Frudua. All rights reserved

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