Fine-Tuning the Adjustment of Passive Humbuckers
It’s been said that the best things in life are free, and I find that saying is never more true than when applied to getting a better tone from our guitars. With so many products on the market that claim to improve guitar tone in one way or another – from fancy new picks made from exotic materials, to super-rare new old stock amplifier tubes someone discovered in a factory basement – it’s a relief to remember that we often can make just as big an impact for free with nothing more than a screwdriver and a few spare minutes.
I am, of course, referring to the ancient and noble art of pickup adjustment.
Passive magnetic guitar pickups work by detecting the velocity of string vibration and converting it to an electrical signal via Faraday’s Law of electromagnetic induction. If that reads like it was written by someone who just Googled it themselves, well… There is a lot of technical information that explains this process, much of which can be gleaned from academic resources and other SD blog articles, so I won’t repeat it here. What I will say is that our pickups “hear” string vibration through an electromagnetic field around our strings. Making adjustments to our pickups changes the shape of that field, which, in turn, changes what the pickup hears and thus, changes our tone.
There are many, many different styles and models of electric guitar pickup (which, if you’re reading the Seymour Duncan blog, should not be news to you), and they each have their own levels and methods of adjustment. For the purpose of brevity, we’ll focus specifically on fine-tuning the adjustment of the common passive humbucking pickup.
In a surprising figure supported by no real data whatsoever aside from my own personal hunch after having consulted nobody, it is estimated that fewer than 50% of people who own an electric are even aware that the humbuckers are adjustable, let alone make any attempt to adjust them themselves. For the other > 50%, here is how I imagine most pickup adjustments are performed:
Guitar owner turns screws on either side of pickup, plays a few notes, declares “YEP IT’S NOT TOUCHING THE STRINGS AND IT SEEMS LOUD ENOUGH I AM DONE NOW I THINK I WANT TO HAVE TACOS FOR LUNCH.”
That would do in a pinch I suppose, but what enthusiasm our hypothetical straw man has for taco lunches, he is lacking for some key aspects of pickup adjustment. I want you to have your tone and your tacos, so what follows is my preferred, in-depth method for humbucker adjustment.
Adjusting for Balance
Balance in this case refers to consistent string-to-string volume. Ideally, with a balanced pickup, one can strum all six (or seven or eight) strings and hear each note ring out with even volume through an amplifier. Balanced string-to-string output is good. It makes our chords sound fuller, our runs and leads more consistent, and helps the guitar respond more evenly, like a higher-quality instrument.
Some guitars happily exhibit this trait acoustically, but even those that don’t can be adjusted so that they do through an amp, and that’s really what matters, right?
String-to-string balance is manipulated via the screw poles in the top of the pickup. Again, designs vary, but they all function about the same.
• If the pickup has flat-head screw poles, we’ll need a flat-head screwdriver.
• If the pickup has Philips-head screw poles, we’ll need a Philips screwdriver.
• If the pickup has hex key poles, we’ll need a hex key of the appropriate size.
• If the pickup has two rows of screw poles, or twice as many crammed into one row (I’m looking at you, Carvin), we’ll need a little extra patience.
The screw poles are named so because they are screws; they are screws because they’re meant to turn, and turning them is how we adjust the string-to-string balance of the pickup. Kind of like putting on pants before putting on shoes, I find it’s best to begin with this step so as to avoid messing up other adjustments we will have already made by doing it later.
So, plug in your guitar and turn them.
Tweak them just enough that the strings all sound like they’re ringing out at the same volume when each one is plucked individually. It’s fine to use a guitar amp to monitor this and trust your ears, but I prefer to use something that gives me a visual readout of the string volume (like an audio workstation or any other piece of equipment with a dB meter) as I make adjustments. I pluck a string, note what the dB meter reads, and adjust the screw pole until it matches the meter readings of the rest of the strings. This way I ensure that my adjustments are accurate and my results are not affected by any compression inherent in a particular amplifier.
If the screw poles in the pickup were already adjusted by someone else or are all wonky for whatever reason, “reset” them by screwing them all back to a position where they’re slightly higher than level with the surface of the pickup bobbin. This way there’s plenty of room to adjust up, but also a little bit of room to adjust down without sinking the poles too far below the surface of the bobbin (which looks weird and can collect gunk over time). The goal is to find a mean depth for all the screw poles, so that none of them wind up too high or too low relative to the function of the guitar when finished.
Adjusting for Output
Once we’ve balanced the poles for string-to-string volume, we can adjust the overall height of the pickup for the desired output level. Output refers to the strength of the guitar’s signal from the pickups. More output = a hotter signal. This typically equates to more volume in a clean setup and more overdrive in a dirty one. Raising the pickup increases the output and lowering the pickup decreases it.
There are other incremental tonal changes that accompany this adjustment. These can range in intensity between different pickup models, but generally speaking, a pickup will sound brighter and dirtier closer to the strings and rounder, darker, and woodier further away from the strings.
I find also that pickups set lower are more responsive to picking dynamics. Whether this is a product of decreased median output and hence, more headroom, or if the lower pickup position physically provides them with a larger “window” through which can detect finer detail in string velocity, I don’t know. Whatever. It works. Practical knowledge FTW.
While 95% of what you need to worry about during pickup adjustment is covered above, there are a few ancillary factors to be mindful of, specifically: clearance, sustain, and pickup-to-pickup balance.
Pickups can be raised up pretty close to the strings without actually making contact while we’re testing out the adjustment, but actual playing conditions do vary and we may find that palm mutes or heavy picking causes the string to choke out some against the pickup. This is decidedly… undesirable. It sounds bad and can cause the strings to wear grooves into the tops of your pickups over time. If this happens, lower that puppy down a hair to get it out of the way.
Passive pickups can also exert a small amount of magnetic pull on electric guitar strings. If the pickup magnet is particularly strong or set too near the strings, it can act as a dampening force on them, reducing sustain, and in extreme cases, actually cause the strings to sound out of tune. The latter is rare, and the former is usually an easy fix, so if you find that your guitar seemed to “sing” more before you adjusted the pickups, try lowering them down a little bit.
The last thing to consider is the output ratio between bridge and neck pickups. This presents something of a balancing act between getting the pickup height just right for each of them so they sound their best individually while keeping their output as complimentary as possible. I find that I prefer a slightly hotter bridge pickup compared to the neck pickup and adjust their height accordingly, but tastes differ on what makes a good ratio between bridge and neck pickup output, so again, trust your ears.
If you haven’t adjusted your pickups using something like the above method, give it a try. I guarantee it will take you less time to do than it’s taken me to write about it!
For those of you who’ve done this many times – could I be missing anything? Do you have any alternative methods? Let us know in the comments.