How do I question the engineering physics of magnetic fields in a guitar pickup?
How do I question the engineering physics of magnetic fields in a guitar pickup?
tl;dr don't bother. This is too abstracted and nuanced. That is okay to skip.
I like to understand the abstract scope of engineering. This is way beyond the simple surface level, with pics below to illustrate my point.
With electric guitar pickups, the complexity of field shaping and design control over the sensor seems like a place where optimising the profitable manufacturability of the final product remains the primary constraint with little deviation.
I struggle to qualify and quantify my intuitive hunch that there is a whole lot more potential to engineer something new and better within the realm of modern manufacturing. I don't know the principal questions I should ask or what might disprove my ideas from the get go.
- Most transformers shape the magnetic field far more than guitar pickups.
- a guitar pickup appears to be more of a two dimensional sensor that picks up the motion of a ferromagnetic string in the two primary directions of motion
- there are more complex harmonic motions present than a pickup can register in two dimensions
- the coil and slugs of a pickup are surrounded by a single large winding, yet the strings each have very different frequencies
- it is now possible to make a powdered ferrite core of nearly any shape and frequency
- the traditional pickup has little effective shaping of the magnetic field path
- guitar pickups are not optimised to a point where they are readily used elsewhere in other sensory applications and devices as economy of scale should dictate in an open and manipulation free market... I don't think they are anyways
- what might be the result if a 270° toroidal powdered core were designed and shaped for each string while tailoring the copper winding and ferrite for each string's mean frequency and shielding each of these
- would a chord segment gap in a toroidal core pick up more 3d motion from the string
- what effect would a primary and secondary winding wound in the opposite dot notation direction have on the pickup of more complex harmonics and motion
- why does none of this matter due to the filtering of LCR and the noise floor or other aspects
Like here is the basic range of commercial products:
The typical schematic of operation:
Basic construction:
This is a typically low noise toroidal transformer that has been around for ages:
Now I need you to abstract this concept with me a little bit. Imagine if a small toroidal core was below each string and offset towards the neck or bridge so that they will fit. Nothing would stick out or surround the string. The 270° is not a radius cut like a pie. Instead it is a chord and removed segment:
There are totally random pics from DDG that are somewhat illustrative in abstract:
These are just some random powdered core ferrites that illustrate how these can be formed into any shape now:
I usually avoid anything audiophile related because it draws out pseudo science nonsense like crazy, but at the center of this question is really a desire for a deeper understanding of sensors and magnetics that have much broader applications in precise motion control and sensors for a range of equipment.
In a higher level of abstraction, I'm also really asking when and where does this subject become the realm of the illusive bearded nude virgin demigods that get enslaved to corpo NDA masters from birth. .5/s
Your... inquiry? into the magnetic field shaping of guitar pickups touches on some interesting engineering possibilities, but it seems you're conflating the simplicity of traditional designs with a lack of innovation. Pickups are indeed optimized for their specific purpose: sensing the motion of ferromagnetic strings and translating that into electrical signals, where manufacturability and cost-effectiveness are primary considerations.
Your suggestion to use toroidal cores and tailored winding for each string could potentially enhance the pickup's sensitivity to complex harmonic motion, but the trade-off in practical terms (cost, complexity, and diminishing returns due to signal filtering) likely limits the broad adoption of such techniques.
Moreover, modern pickups function well within the constraints of musical performance, where the focus is often tonal character over scientific precision. If you're seeking a deeper understanding, it's worth considering how current designs reflect a balance between engineering feasibility, cost, and the subjective nature of sound in music. Moving beyond that, you're entering the realm of motion sensors or experimental designs—potentially valuable but perhaps not practical for most applications.
Would this more intricate engineering result in a noticeably better product for the average guitarist? No. Would it just be a niche curiosity for audiophiles and engineers? Also, probably, no.
Would this more intricate engineering result in a noticeably better product for the average guitarist? Would it just be a niche curiosity for audiophiles and engineers?
This is AskSCIENCE so it's not surprising that you would approach the musings from this perspective.
But OPs idea is about the intersection of science and art. I think the question is really: Would some of these ideas result in an output signal that was controllable in a new way?
Imo this modification would empower an artist to interact with their guitar in a novel and creative way? Do I think we'll see mass adoption, no, but I think there are definitely people out there that would be interested in playing a guitar with pickups like this. Even if it's just part of their creative process.
You are generally correct that pickups are relatively primitive devices. However, a guitar is not a device which is intended to perfectly capture the high order dynamics of a plucked string. It is a device which is intended to produce a musical abstraction of that process.
a guitar pickup appears to be more of a two dimensional sensor that picks up the motion of a ferromagnetic string in the two primary directions of motion
It’s actually not a 2 dimensional sensor. It’s 1D, the velocity of the string induces a current in the coil (Faraday’s law)
there are more complex harmonic motions present than a pickup can register in two dimensions
Again not sure where 2d is coming from, but the current perfectly corresponds to the velocity of the string, which we already know is identical to the sum of the velocities created by all of the harmonics (Fourier Transformation).
How did you reach the conclusion that some harmonics are missing from the resultant signal?
the coil and slugs of a pickup are surrounded by a single large winding, yet the strings each have very different frequencies
The human ear also has different sensitivity to amplitudes at different frequencies, with higher pitched sounds not needing as much energy to reach the pain threshold. The distance between each string and the pickups is also adjusted during setups, sometimes including tilting the pickups themselves depending on the type of guitar.
Just a few thoughts I had while reading. This style of pickup really is just popular just because the’ve been popular for so long and they’re supremely reliable even with as much abuse as we put guitars through. There are others; you might enjoy reading about the physics of a piezo pickup, and the problems they often create for players haha
How did you reach the conclusion that some harmonics are missing from the resultant signal?
I forget if it was Veritasium, Steve Mould or one of the other edutainment content creators that was showing how waves move through a string and form the extra major harmonics along the length. I was half baked thinking of that and how the string is not constrained to a single plane of vibrations.
I am thinking of the motion of the string being more complex, like if I placed a coil under the string and one at 90° to the first beside the string, there should be a subtle difference between the two signals. The motion of the string may be oscillating entirely within the field of each pickup coil, but the motion with respect to the magnetic pole of the pickup will be different. If two fields are pointed at the string from opposing angles, perhaps more of this motion is defined. It might alter the sound for more subtle picking techniques like plucking, slapping, palm muting or others.
Also there is the question of what is the optimal turns ratio and signal for each string. If each string had its own pickup and winding, it is like audio channels on a mixer, it creates versatility and nuance. It's just an idea.
there should be a subtle difference between the two signals
Not really. It sounds generally like you’re overvaluing the role of a plane relative to the magnetic poles. The string moves somewhat circularly, like a jump rope. It doesn’t matter how you angularly orient the pickups, all else being equal.
As for per-string pickips, hey, I’m all for it. Give me 6 output jacks as well so that each string can get its own effects chain.
Have you ever considered getting into synthesizers? Based on your thoughts I feel like you’d really enjoy making synth patches
So, you are making half-baked ideas, vaguely recalling a YouTube video, and decided to reinvent guitar pickups based on string motion in multiple dimensions? Ok. The reality is that modern pickups already capture harmonics quite well—that’s why guitarists can play harmonics by lightly touching the string and why we can hear the rich overtones in complex chords. Your idea of capturing "more" harmonic detail by adding a second coil at 90 degrees might sound clever in theory, but let’s be real: any actual benefit would likely be drowned out by filtering, noise, and diminishing returns in the real world.
The suggestion of giving each string its own winding and turns ratio is ... fine, I guess, but this isn’t mixing a multitrack recording; it’s a guitar pickup designed to balance simplicity, functionality, and tone. Innovation also means accepting when a system is already pretty optimized for its purpose, not adding complexity for the sake of chasing minor nuances that might only appeal to a tiny fraction of people who know what "half-baked" string theory even means.
You could certainly make something different, but it wouldn't necessarily be better. Electric guitars have a very well established sound. I'd imagine most people want to have that same sound, or at least something very similar. Those who want a different sound use all kinds of stuff on their pedalboard.
So I'm more thinking about resolution and dynamic range at this level of abstraction. It is not a question of new sound, but more like texture for various modes like palm muting, clarity, adjustability, or natural/pinch harmonics. Most effects are basically modes of bad audio in amusing ways from clipping to poor recording delays, or what it sounds like to play audio through junk materials like plates or springs. Pursuing perfection is nonsense for sure; pursuing resolution and nuances might yield new and unique sounds.
That's pretty much what pedals are for..I feel like you're coming up with a solution to a problem that doesn't exist
I guess you're too worried about mass manufacturing history and physics theory. Why not get a few cores, buy some winding wire and set up a rig and give it a go?
I'd suggest attempting it. You've got enough written down here to make a test plan, you'll want to use the same strings, same tension etc and just... Listen.
Our senses, though nowhere as refined as other animals, are still able to notice things one may not note on an o-scope display.
And perhaps moreso when it comes to a musical instrument, what out senses perceive is more important than what one may note on an o-scope.
Sure, all of what you say is correct. I'm more pointing out the interesting textures and other subtle things which may not be immediately obvious on a screen, e.g. if the timescale is too zoomed in... I've missed phenomena before for that exact reason on a 'scope.
With the risk of sensing things that are not there, though. OP mentioned weird audiophile shit.
Yeah, possibly.. iunno, one life and all. Have fun with it 😎
You should look up Fishman Fluence pickups, they've been all the rage in metal circles for a few years and they are in fact made by stacking PCB-like layers rather than in the traditional way.
Dunno, give it a try. With a bit of research to hammer out fine details, a mic jack and some cores could be enough to build what you're describing. Do they make cores like this already, or are you going to have to manufacture them yourself?
The trick, of course, is that you're still going to get a single-wave output, and postprocessing exists that can easily reverse arbitrary distortion in the audio range. Apparently a guitar that doesn't pick up the full range of string motion sounds good enough, at least.
Are you saying you could come up with a better design for a pickup?
Maybe... probably not...
It is a long-time back-burner idea I've toyed around with and mulled over, but the first time I've ever tried to externalize it.
I've wound my own transformer and filter magnetics, but have never messed with audio like this and probably never will. It is just a curiosity. I do not have a very complete or deep understanding of the physics or math.
You should read about (and check out the demos for) Q‐Tuners. They're humbucker pickups based on Neodynium magnets that capture upper harmonics and detailed dynamic range that other pickups would muddy.
Pretty interesting stuff. It seems to me they need a bit more love from EQs and such to sound "right" through an amp compared to other pickups, but having a cleaner source signal definitely seems to capture something extra
I think it's a neat idea. I've responded to a few other commenters with my thoughts too, so check the thread.
Considering electric guitar sound is distorted so much, I'm not sure what could be gained from a more sensitive pickup. After reading a few comments here, current pickups are plenty good enough, reliable, and can take abuse.
Interesting ideas! I encourage you to make a prototype and see how it goes!
A couple open ended questions:
-What does the frequency response of a traditional pickup look like? Is it flat or does it ripple/drop off significantly? Is that corrected somewhere else in the audio chain before it reaches your ears?
-Human hearing only stretches to about 20KHz. If your pickups capture everything up to that frequency then you're really not missing anything. I don't know much about pickups but in my line of work 20KHz is a very small bandwidth, so I would guess it's not difficult to build one that has a nice flat response over that whole band.
-Human hearing perceives different frequencies at different amplitudes. If your goal is to produce 'perfect' sound (i.e. undistorted reproduction of the vibration of the strings) perhaps it would make more sense to correct for that?
-Your idea of changing the orientation of the magnetic field that interacts with the field of the strings of the guitar is interesting. I'm guessing the majority of the signal picked up by traditional pickups is from the component of the string's magnetic field that's aligned with the axis of the pickup. However I would imagine regular strumming produces more vibration perpendicular to that axis than parallel to it. I could see your idea more effectively capturing that energy and producing a larger signal. That would probably give you better signal to noise ratio and effectively give you better sound quality. Whether it's a perceptible change or not is a different story.
Oooh, I can answer some of this!
Frequency response is DEFINITELY non-linear in a traditional pickup. The nonlinearity is one of the prime factors in the tone of a pickup. (And unlike with say home audio amplifiers, there is no argument about the variation in tonality of different pickups.)
How?
Easy. Observe-and I quote "how do I question the engineering physics of magnetic fields in a guitar pick up?" -j4k3