How to adjust the distance of a
single coil pickup from guitar strings.
In this article you will find instructions and tips about pickup height setting on electric guitars, with special regard to single-coil models. Another article of this blog deals with double coil or humbucking pickups. This is part of the general setup of the guitar, that involves topics covered on the Soundsation blog, as neck truss-rod and action adjustments.
Before continuing you should have:
All that verified, we can talk about how self-adjusting single-coil pickups working on their mounting screws on the pickguard or guitar body.
Magnets and coils
An electric guitar pickup is an electro-magnetic transducer that converts string vibration into an electric signal. Easier said, it is a set consisting in coils (isolated electric wire), magnets (permanent magnets made of magnetizable materials as Iron, Nickel and Cobalt), eventually some pole pieces, and an enclosure.
An electro-magnetic field surrounds the pickup magnet and electrical particles move from the North pole to the South pole of it. When this field is disturbed by string movements (strings must be made of metal to interact), an electrical voltage is induced and it varies as the string vibrations change. This variable electric signal reaches the guitar jack output through the coil, volume and tone potentiometers, and then it is send to the amplifier to be amplified and converted into sound waves.
It can therefore be understood that string-pickup interaction has a lot to do with their distance, in addition to the electro-magnetic field strength and shape.
Common pickup magnets are made of Alnico (Aluminium, Nickel, Cobalt and Iron) in its different classifications (2, 3, 4, 5) or ceramic (Iron oxide powder and Barium or Strontium carbonate ceramic), also called ferrite, more fragile but cheaper. Ceramic magnets can be recognised at sight thanks to their dark colour, whereas Alnico is shiny. Some magnets are produced with the contribution of alternative materials, as Rare Earth elements Neodymium and Samarium.
Kinds of single-coil pickups
Single-coil pickups consist of one isolated electrical wire coil and one or more magnets. This simple design has been firmly resisting since the '50s, but can easily make these pickups behave as antennas, thus picking up electromagnetic interferences, particularly hum from household electrical wiring (230V 50Hz or 120V 60Hz according to countries). This problem was solved by humbucking pickups we are talking about in another article.
According to construction, single-coils can be of the following types:
Starting from these general types, we have been seeing attempts of all kinds through the decades, mixing coils, magnets, poles, sizes and so on. CNC machines introduction helped making tight ultra-thin wire windings in processes that were impossible in the '50s and '60s. For more reference, there are excellent books about pickups and their evolution (*).
Setting single-coil pickups
Correctly setting a single-coil pickup is a pretty easy operation. For example, Fender specs for Strat vintage style pickups indicate a distance of 2.5 mm between the 6th string and 2 mm between the 1st string and the pole pieces, measures taken while keeping the strings pressed on the last fret. I defy anyone to assess at sight a difference of half a millimetre! Original values are given in inches – I slightly rounded them – and are the same for the three pickups. Let's consider this a starting point, also good for similar single-coils.
Let's start from the bridge pickup
Start playing and listening to the sound of open strings. Begin with the bridge pickup and lower it unscrewing its pickguard screws: a quarter of turn usually produces audible variations. Evaluate the sound you get: is it fuller or thinner? More or less rich in harmonics? More or less brilliant? Too dry or too flat? Is the note attack too hard?
Staying on the bridge pickup continue by attempts, always doing minimal intervention on screws, and listen to the result. At some point you will feel like the sound is becoming too thin or weak. Go back to the previous position until you find the exact point the sound seems to be the right one, or the sweet spot. Some experts use to say in focus sound, because you are in fact adjusting the interaction between the electro-magnetic field and the string vibrations as you were focusing a subject in an optical lens.
This way of setting a pickup height
applies to your specific instrument with that pickup, those strings, based on
your essential taste and well trained ear.
Sometimes, even on pros' guitars, it happens to see pickups that are too close to the strings, searching for a more powerful and bassier sound. Actually a pushed sound with little sustain is obtained, since string vibration is limited by the pickup magnetic pull. Back on this soon...
Let's go to the neck pickup
Once you have set the toughest pickup, the bridge one, you can handle the neck pickup, that always gives a louder and fatter sound, because of its position where string vibration is broader. You have to lower the pickup just enough to get a sound that matches the bridge pickup in volume. Moving the switch from a pickup to the other, you should not hear big level differences. This is valid for a Strat middle pickup too. In fact, if the guitar has three pickups, the process is the same. Personally, I always start with the bridge pickup, then go on to the neck one and complete with the middle pickup.
Go on following the described ear
guided method to get better nuances from every pickup.
P-90s and other single-coils
P-90 or soap-bar style pickups have a wider magnetic field, extending on sides due to the use of two magnets under the coil and pole pieces instead of real magnetic poles. They can be adjusted in the same way as single-coils, but you have to consider a behaviour somehow halfway between those and humbuckers.
Instead, DeArmond or Dyna-sonic style pickups have massive magnets as poles. You have to set them with care, both the whole pickup and the single poles.
Basically, if you keep the magnets low and the full pickup close to the strings, the sound will resemble a P-90. In contrast, if the pickup is moved away from the strings whereas the magnets are kept near to them, it will sound like a fat brilliant single-coil. In-between there are a lot of possible adjustments.
Due to appeal reasons, sometimes soap-bar or DeArmond or humbucker looking pickups are used on lower priced guitars. Under their covers you will often find Strat style pickups that must be adjusted as Fender single-coils; but you have to know their nature beyond marketing releases.
Lace (or hook) effect
Talking about single-coils, you must absolutely consider that nearly always their magnets are the poles; in other words, the six little cylinders! In the case of a Gibson style humbucking pickup, the magnetic field wraps the strings and the pickup somehow like a loaf (the magnet stays horizontally under the coils), whereas in the case of Fenders each magnet generates a magnetic flow pretty aimed at the overhanging string. If the magnet (or pole) is too close to the string, its vibration will be dampened or not naturally sounding, as if it were hold by the pickup acting like a lace or hook. Sometimes it could be impossible to set octave intonation and double notes or even fret buzz could be produced!
So, watch out for hot single-coil pickups with oversized and boosted cylinder magnets, especially at the bridge position, where the strings are closer to saddles and have less energy. Single-coils with a single magnet under the coil produce a less direct magnetic flow and give less trouble.
The described adjusting method is good for those with a certain experience. If you feel you are not able to follow it, manufacturer's specs can be taken for granted. Turning to a luthier or a skilled technician is always advisable.
Sometimes you can get unexpected reactions. If you want more bass, do not raise the pickup at the wound string side, instead lower it at the treble side; and vice versa.
A proof of successful setting comes from listening to the switch middle positions: if the sound is not typical and pleasant, you'll have to review something at least for one of the pickups.
If the pickups are very different from each other, by example if the bridge pickup is a lot more powerful than the neck and middle ones, you'll have to turn to splittable pickups or accept some compromise solutions: an audible difference of volume or some drive sacrifice in the most powerful.
Poles and pole pieces
Single-coil pickups almost always have six not adjustable cylindrical magnets or pole pieces. Length can be the same for all (flat pole pieces) or varied according to the string gauges once available (staggered pole pieces).
If you find screws in place of cylinders and you notice clear volume differences among the strings, use the screws to get a balance. Play, evaluate and screw or unscrew the poles until the strings produce the same sound level. Start from the factory setting and try to follow the fretboard radius, though your ear is always the final judge.
It is possible that something changes when you switch from clean sounds to saturated sounds; there is nothing wrong with retouching a pickup setting while an overdrive pedal is turned on.
Getting less problems
Undoubtedly pickups with blades and active pickups are easier to adjust. The first ones because you don't have to care about screw poles; the second ones because their magnetic field is not excessive and their strength comes from an active circuit. In these cases we can follow manufacturer's instructions. By example, an EMG pickup requires a distance of 3 mm from the strings pressed at the last fret; thereafter adjust at your own taste.
I have to mention Lace Sensor pickups again. Their particular design greatly reduces magnetic field influence and points it to the outside of pickup, practically cancelling any lace effect.
Still talking about magnetic field control, similar solutions are implemented in Kingman pickups and in some DiMarzios (a suit occurred between the companies in this regard), that however use two coils.
Have a good setting
As I said, in another article we deal with the adjustment of double coil or humbucking pickup, in which case things are a little different and more elaborate. Information provided here about single-coils should be enough to get a clear, full and balanced sound from your guitar. But always beware of laces!
.Milan, Pickups - Centerstream Publishing, 2007