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I hear a lot of hocus pocus in music. One such thing called "Premium" pickups are heralded as some must-have for a good sounding guitar.

To me, it seems like pickups are just electromagnets and their performance is governed by the laws of electrodynamics, not marketing. So why on earth would anyone spend 250 european thalers(!) 😱 on a glorified electromagnet?!

I see the following physics affecting the frequency response of a pickup:

  • magnetic field strength
  • magnetic field location relative to the strings
  • winding thickness, turn count and internal resistance
  • inductance

other factors not related to the construction of the pickup:

  • pickup position along the length of a string (standing wave harmonics)
  • cable capacitance (and tone capacitor)
  • load resistance

I'm sure I'm missing something, so...

What determines the tone/frequency response/distortion of a pickup?

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    Those four things you listed are the main things affecting the response of a pickup (and don't forget the dynamic range, noise, and distortion in addition to frequency response). The thing is, we can hear even minor differences in any of those four factors, because the human ear is amazingly sensitive. Also, getting a certain field strength or winding thickness, turn count, etc., can be very tricky. So making a pickup that sounds just so is not easy, and can be expensive. – Todd Wilcox Jul 8 '20 at 4:28
  • Pickups do not have a min/max field-strength they can measure and don't have distortion by themselves. (ergo:they dont have dynamic range) Amplifiers do have a dynamic range (and distortion). The noise profile is a property of the 'whole' system (incl. amp/cable). Some pickups are marketed as 'noiseless' and I don't buy it. Either it's a humbucker that blocks common-mode signals or you get mains hum from a single pickup. -- But what determines the frequency response? None of the things listed determines the frequency response of the pickup! (Amplifier distortion is something else, obviously) – Xunie Jul 8 '20 at 6:33
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    Note: pickups don't measure a string's position when it leaves the pickup's magnetic field. So there is some form of non-linearity when the strings effect on the magnetic field (and thus the electric field) start dropping off. But is that distortion because of the pickup itself? Depends on how you look at it. It's actually a property of the string/pickup setup, not the pickup itself. Seems like this will have a major effect on tone, which is confirmed by endless internet resources telling you to adjust pickup height! Certainly important to note here! – Xunie Jul 8 '20 at 6:37
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    @Xunie to be fair, an absurdly large, fast-moving string could saturate the core. I agree not in any realistic guitar. – Carl Witthoft Jul 8 '20 at 13:51
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    I’m afraid some of your comments suggest that there’s knowledge of physics and electrical engineering that you might be lacking. Magnetic fields don’t end, they decrease In strength over distance by the inverse square law, and could be blocked in some cases. Guitar strings are never outside of the magnetic field of the pickups. Also distortion is caused by all non-linear components and boy howdy are pickups non-linear. Since pickups respond differently when the guitar is played harder or softer, they definitely have a non-zero dynamic range. – Todd Wilcox Jul 9 '20 at 2:04
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That first bit of your post is a bit of an unfounded rant, so here's an analogy:

A quick analogy - why would anyone pay thousands for a bottle of wine? They are all just grapes.

Because they want specific wines - perhaps rarity, perhaps reputation, perhaps because the wine/pickup is exactly the way they want. They are all different, with nuances a particular individual may want.

Your actual question, though, is good. You are correct that the main factors affecting tone response are magnet strength, winding count, internal resistance, wire gauge, inductance, field position under the strings, however there are further nuances:

  • distance to strings is important, but where the field sits in relation to each string is also key - see multi-pole magnets, single bar pickups etc.
  • physical construction - both in terms of potting the coils, but in fixing the pickups to the guitar body. Yes, pickups are all about EM, but if the pickup is resonating/vibrating, its relationship with the string changes
  • gain - while not creating distortion itself, a high gain pickup will feed in "hotter" to your preamp/input stage so brings the signal level closer to distorting. It also can increase signal to noise ratio

Remember, each factor has side-effects, such as stronger magnets damping the strings more, which affects the response across the frequency domain and the time domain.

And of course the electric circuitry in your guitar and amplification chain can then alter any part of the sound - but that is a separate issue :-)

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    I really love the wine analogy. – gingerbreadboy Jul 8 '20 at 16:08
  • I think we can all agree that wine snobbery and toxic marketing are very real things that affect wines (as well as pickups). ;-) Strong static magnetic fields do not dampen the strings by themselves as the field is static. If I am to believe this guy, he says that the electromagnetic coupling of the pickup to the string is negligible and doesn't cause sustain issues either. – Xunie Jul 9 '20 at 0:01
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    Sadly that guy is only talking about the static field. He fails to mention the extent to which the string gives energy to the pickup (a "hotter" pickup gives higher output - that energy has to come from somewhere) – Doktor Mayhem♦ Jul 9 '20 at 16:55
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You are essentially correct, but it might be good to look at this from a couple of angles. Single coils are single coils, right? Well... sort of. Lets take two single coils with very different sounds...

Compared to other single coil designs, such as the ubiquitous Fender single coil, the bobbin for a P-90 is wider but shorter. The Fender style single coil is wound in a taller bobbin but the wires are closer to the individual poles. This makes the P-90 produce a different type of tone, somewhat warmer with less edge and brightness.

This is essentially the practical application of what you have listed in your question, but it is quite a big, bold difference. Subtle differences in construction make a more subtle difference...

Scatter Wound is the idea that the wire is wound in patterns that are not nice perfect rows. Certain winders do it certain ways and therein lies the better part of the nuance of a pickups’ sound. Therein lies the art. A painting can be copied and still be a beautiful painting, but if it had to be reproduced by hand by another painter, the art of the painting would be found in the nuanced differences of colors, brush strokes, and even mistakes.

Can one pickup builder scatter better than another. Maybe, maybe not. But could one pickup builder be said to scatter more consistently from pick up to pickup? Yes, I'd say so. So I'll pay more for a brand-x because i know that the product is consistent, it will sound exactly like the demo i heard.

Then we get to tolerance. Every component (be it an elctronic/electrical or mechanical part) has a tolerance. Bobbin manufacturer-x produces bobbins to a highly precise tolerance, more so that manufacturer-y. This makes the wire layout slightly more predictable. So again, pickup builders who use the more expensive X bobbin have a more consistent and predictable product, but much charge more. Same goes for wire gauge and magnets and everything else.

So now I've got two manufactures one who makes pick-ups which sounds fine, and one who makes picks which are very tightly spec'd and manufactured to a high tolerance from the ground up.

As a consumer I can buy either, but if I want a very specific sound the higher price tag gets me closer to that sound. Is the sound better, not objectively but it is in line with my expectation more so.

And then... If I can produce things to a tighter spec, I can diversify in a narrow space. Trad Telecaster pickups "all sounds the same" except you can get 52s, 54s, 56s, 62s, 68s and on and on which are subtly different. The R&D time and effort and the quality control required to slice up this narrow market is expensive and that cost is passed on to the consumer. The 52s aren't better, the 68s aren't better, but they are more tightly controlled than the generics.

I'm not really in to expensive pickups, but that's mostly because I've never been after that tone, other than replacing a super-budget humbucker with a $35 P90 because I wanted P90 tone in my second Tele.

If I was replacing the trad pickups on my beloved Tele though, yeah I'd do the research and spend the dollar.

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  • Okay, tolerances and repeatibility. Maybe quality control in general. Important qualities to have in products. But I still wonder what determines the tone? – Xunie Jul 9 '20 at 0:09
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    @Xunie - gingerbreadboy and I, and Todd and Carl have told you what contributes to the tone from the pickups. For most of my guitars, though, I get more of a change in tone from the wood, bridge, construction of the guitar, and even more from the remainder of the electrics, so you may be focusing on the wrong thing here... – Doktor Mayhem♦ Jul 9 '20 at 16:59

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