Most pickups have a number of ‘pole-pieces’. These are are the screws or ‘slugs’ that you see in your instrument’s pickups.
Some instruments only have the non-adjustable slug-type poles (and you definitely should not try to adjust those) but many pickups will be fitted with screw-type poles that can be raised or lowered.
By adjusting each screw pole, you can balance the output of each individual string.
Last time, when I talked about matching pickup pole piece heights to the same radius as the strings, I didn’t give you the whole picture.
Truth is, it’s a bit more complicated.
Update and Warning
(Dec 2, 2017) Someone was kind enough to leave a comment mentioning they found this article after adjusting the poles on their Strat pickup. This made me realise that, while I mention that some pickups have non-adjustable poles and I only discuss screw pole pieces, I didn't make absolutely clear that you should not try to adjust any pickup poles that do not have a screw-slot or hex-head slot.
Many of the Fender-style single coil pickups are non-adjustable pickups can be damaged if you try to adjust them. Don't be tempted to push any of the slug-type poles (the ones with no screw-slots/hex-head).
I have added a parenthetical in the text above and I'm adding this warning here. Only adjust screw or hex-head pickup poles. The ones that are meant to be adjustable.
String output and pickup poles
By raising the screw pole-pieces into an arc matching the string radius, you will even out the distance between each string and its associated pole.
That’s all fine.
Until you remember that the actual ‘influence’ each string can have on the pickup’s magnetic field is not the same.
Some strings, essentially, have more output than others.
Wound and unwound string output
Conversely to what you might think, the unwound strings can have more output than the wound strings. This is because it’s the ‘core’ of the string that gives most of the ferro-magnetic action rather than the wrap windings.
Therefore your skinny strings might actually have more output than that big fat bottom string.
There have been efforts to address this string imbalance over the years and it’s worth having a read about pickup pole-piece stagger.
What string imbalance means for adjusting pickups
What this means for someone adjusting their pole-piece screws is that following the string radius is good, but not great.
We need to compensate a little more (or a lot more in one case) to get a better string-to-string balance.
The ‘G-elephant’ in the room
I made a bad joke by putting a ‘G’ at the start of ‘elephant’. Sorry.
The unwound G string is the main problem though. That unassuming little guy has the most output of all the strings on your guitar. Honest.
So, when you’re adjusting pickups to get a consistent volume across all your strings, that’s the one that needs more attention.
So, you’ll want to adjust that G way down compared to your other strings.
How the whole picture looks
This is a rough idea of the heights I generally set on adjustable pole pieces.
Yes. That G string pole is below the top of the pickup.
Well, like a fox, I say!
Just try it and have a listen.
Of course, it’s important to note that this is a rule of thumb. Think of it as a good starting point. Set your screw poles in roughly this pattern and then listen to each string’s output. Don’t be afraid to adjust things if your ears tell you something’s not right.
Ears are the most important tools.
Plain versus wound G string
The pattern above only applies to plain or unwound G strings.
A wound G string is the opposite and actually needs the pole closer to the string. If you play a wound G, bring that pole piece higher even than the D string.
But, but, the little strings are far away
Our natural inclination is to adjust the pickup closer under the first couple of strings because they look so wimpy. That’s not always a good idea, though.
Listen to the output as you play slowly across the strings. Try to listen to the output or volume rather than the ‘tone’.
Then adjust as needed.
Screw slot pattern
Should the slots in the top of the screws be adjusted in any particular pattern? Should you turn the screws so they point in a particular direction?
Nope. I don’t think so.
There has been a school of thought that an alternating diagonal pattern (similar to that shown above) is best — possibly because adjusting poles to the string radius can end up like that. Personally, I don’t hear any difference according to which way the screw slots orientate.
I don’t like to line the slots up with string direction but that’s aesthetic rather than for any tone reasons. Feel free to ignore this particular quirk of mine.
Use your ears, not your eyes
The bottom line
I know that the pole height pattern above looks weird. Try it, next time you’re setting up, though. Use those lugs on the side of your head and see how the string-to-string output sounds.