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
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.)
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.
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?
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.
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.
With the risk of sensing things that are not there, though. OP mentioned weird audiophile shit.
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.
