timtam
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Post by timtam on Nov 17, 2023 23:56:04 GMT -5
As part of maintaining my library of guitar science research, I have coincidentally accumulated what is probably close to the sum total of the published academic research on guitar pickups in scientific journals and conference proceedings (and a few theses). That particular research "niche" is not a large body of work. There's no real "scientific community" of academic pickup researchers, nor journals or conferences that regularly attract work on pickups. But I thought it might be interesting to list those works here for anyone who wants to read them. Most of the work was probably done as a "side-gig" by a university academic engineer/physicist/scientist who is expert in a related field but who also happens to play guitar, or because a grad student wanted to do their thesis on pickups (but most high-level scientific research groups don't give students a free choice of their thesis topic) and then published a paper or two from that. In any case there is no guarantee of lots of useful insights let alone revelations here. There is other work that could also be termed "academic" in nature that's been covered here before. The McDonald technical report has been covered, as has Jungmann's thesis, Manfred Zollner's work (and other work by GITEC), the work of Helmuth Lemme, as well as that of Stephen Errede, Malcolm Moore, Donald Tillman, and probably a few others (links in my later post below). But most of those works are not journal publications or published conference presentations, which does distinguish most of the works below - granted that publication in such places does not indicate research 'quality' in any real way. In any case I don't think the published works listed below have come up here before. If you can't get any of the full papers at the link provided let me know. Sci-hub (that is the source for some) may be blocked in some locations (you can try a VPN, or the VPN within the Opera browser; or Tor, or the Tor interface in the Brave browser; or google the paper title and maybe another source will come up). If anyone knows of any other such papers, let us know too.
Feinberg, J., & Yang, B. (2018). Natural-frequency splitting of a guitar string caused by a non-uniform magnetic field. The Journal of the Acoustical Society of America, 144(5), EL460–EL464. sci-hub.se/10.1121/1.5080465
Giampiccolo, R., Bernardini, A., & Sarti, A. (2023). Virtualization of guitar pickups through circuit inversion. IEEE Signal Processing Letters, 30, 458–462. www.researchgate.net/publication/370167984_Virtualization_of_Guitar_Pickups_through_Circuit_Inversion
Guadagnin, L., Lihoreau, B., Lotton, P., & Brasseur, E. (2017). Analytical modeling and experimental characterization of a magnetic pickup for electric guitar. Journal of the Audio Engineering Society, 65(9), 711–721. sci-hub.st/10.17743/jaes.2017.0024
Harazono, M., Kitamura, D., & Nakayama, M. (2012). Humbucking pickup response excited by string vibration. Acoustical Science and Technology, 33(5), 301–309. doi.org/10.1250/ast.33.301
Horton, N. G., & Moore, T. R. (2009). Modeling the magnetic pickup of an electric guitar. American Journal of Physics, 77(2), 144–150. sci-hub.st/10.1119/1.2990663
Lemarquand, G., & Lemarquand, V. (2007). Calculation method of permanent-magnet pickups for electric guitars. IEEE Transactions on Magnetics, 43(9), 3573–3578. sci-hub.st/10.1109/TMAG.2007.891671
Nishiguchi, I., Kaimori, H., Kameari, A., Takebuchi, E., & Nojima, Y. (2019). Modeling of magnetic pickups for electric musical instruments. 2019 22nd International Conference on the Computation of Electromagnetic Fields (COMPUMAG), Paris, France. sci-hub.st/10.1109/COMPUMAG45669.2019.9032828
Novak, A., Guadagnin, L., Lihoreau, B., Lotton, P., Brasseur, E., & Simon, L. (2017). Measurements and modeling of the nonlinear behavior of a guitar pickup at low frequencies. Applied Sciences, 7(1), 50. doi.org/10.3390/app7010050
Novak, A., Guadagnin, L., Lihoreau, B., Lotton, P., Brassseur, E., & Simon, L. (2016). Non-linear identification of an electric guitar pickup. Proceedings of the 19th International Conference on Digital Audio Effects (DAFx-16), Brno, Czech Republic. www.researchgate.net/publication/308076553_Non-Linear_Identification_of_an_Electric_Guitar_Pickup
Novak, A., Lihoreau, B., Brasseur, E., Lotton, P., & Simon, L. (2020). Guitar pickup: Measurement of its two-dimensional nonlinear function. Journal of the Audio Engineering Society, 68, 184–192. sci-hub.st/10.17743/jaes.2020.0002
Novak, A., Lihoreau, B., Lotton, P., Brasseur, E., & Simon, L. (2018). Experimental study of guitar pickup nonlinearity. Proceedings of the 21st International Conference on Digital Audio Effects (DAFx-18), Aveiro, Portugal. 280–287. dafx2018.web.ua.pt/papers/DAFx2018_paper_39.pdf
Outside the scope of the specific pickup-related papers here, there are some other papers that address sound synthesis of electric guitar sounds. They are often simply exercises in digital signal processing to model the output signal characteristics, and may not reveal much about real pickups per se. eg Lindroos, N., Penttinen, H., & Välimäki, V. (2011). Parametric electric guitar synthesis. Computer Music Journal, 35(3), 18–27. sci-hub.st/10.1162/COMJ_a_00066Similarly there is a number of papers on estimating things like pickup position from their output. eg Mohamad, Z., Dixon, S., & Harte, C. (2017). Estimating pickup and plucking positions of guitar tones and chords with audio effects. Proceedings of the 20th International Conference on Digital Audio Effects (DAFx-17), Edinburgh, Scotland. 420–427. www.researchgate.net/publication/324756820_Estimating_Pickup_and_Plucking_Positions_of_Guitar_Tones_and_Chords_with_Audio_EffectsI can provide lists of those works too if anyone is interested.
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Post by newey on Nov 18, 2023 12:40:27 GMT -5
timtam- A Tour de Force, and will be a useful resource. However, it's a bit hard on the eyes. You might consider formatting the bibliography by spacing in between entries, or using the "List" tool to bullet-point the items.
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timtam
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Post by timtam on Nov 18, 2023 22:02:19 GMT -5
timtam- A Tour de Force, and will be a useful resource. However, it's a bit hard on the eyes. You might consider formatting the bibliography by spacing in between entries, or using the "List" tool to bullet-point the items. Good suggestion. Spacing now done.
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kitwn
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Post by kitwn on Nov 19, 2023 17:34:19 GMT -5
As someone who has been learning about pickups recently and hoping to do some experiments with my own designs and electronics, this is a brilliant resource. Who'd have thought there was so much to say about a magnet with a bit of wire wrapped round it?! Do you study psychoacoustics as well? It's all part of the mix.
Thanks for posting this list.
Kit
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timtam
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Post by timtam on Nov 19, 2023 22:57:12 GMT -5
As someone who has been learning about pickups recently and hoping to do some experiments with my own designs and electronics, this is a brilliant resource. Who'd have thought there was so much to say about a magnet with a bit of wire wrapped round it?! Do you study psychoacoustics as well? It's all part of the mix.
Thanks for posting this list.
Kit
For someone just starting to dive more deeply into pickup physics, it's probably best to begin with the works I mentioned that have already come up around here:
Zollner, M. (2022). Physik des Magnettonabnehmers. Regensburg, Germany: Selbstverlag (Self-published).
Also just remembered that some of these are also listed here (along with some others):
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Post by ms on Nov 20, 2023 6:19:28 GMT -5
Towards the end of of Tillman, "Response Effects of Guitar Pickup Position and Width":
"Pickups do not sense the string at a single point source, but rather over an area due to the width of the magnetic field. This sensing area is called the "aperture" of the pickup and is about an inch wide on a thin single coil pickup and about 2.5 inches wide on a wider pickup such as the Gibson humbucker."
I wouldn't refer to this unless he fixes it. This is a popular article, and so responsible for much misunderstanding.
McD's article is a great introduction to how the law of magnetic induction works, but it is very much intended to be viewed with "physics thinking", that is, something made fun of by the old joke about assuming a spherical cow. His assumptions about the magnetic field from the string are not in line with reality, and he does not make this clear.
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Post by newey on Nov 20, 2023 6:29:02 GMT -5
Stickied this thread for posterity.
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timtam
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Post by timtam on Nov 20, 2023 9:39:07 GMT -5
Towards the end of of Tillman, "Response Effects of Guitar Pickup Position and Width": "Pickups do not sense the string at a single point source, but rather over an area due to the width of the magnetic field. This sensing area is called the "aperture" of the pickup and is about an inch wide on a thin single coil pickup and about 2.5 inches wide on a wider pickup such as the Gibson humbucker." I wouldn't refer to this unless he fixes it. This is a popular article, and so responsible for much misunderstanding. McD's article is a great introduction to how the law of magnetic induction works, but it is very much intended to be viewed with "physics thinking", that is, something made fun of by the old joke about assuming a spherical cow. His assumptions about the magnetic field from the string are not in line with reality, and he does not make this clear. It would be good if these lists prompted some discussion like that, especially where there are things that are not quite right. With no real "community" of academic pickup researchers, the published works in the lists will probably not have been through a very rigorous peer review process. There just isn't a pool of known academic pickup experts for journal editors to send submitted work out to for review. So the papers are very likely to have only been reviewed by a generalist, or an expert in only a vaguely related field. Many conference papers are barely reviewed at all. Really good work doesn't really need that rigorous review, but poor work can slip through into publication without it. And theses are hit or miss quality-wise - if you know your student's thesis is high quality work you'll send it to high-level assessors; but if you know it's not great, maybe it goes to softer assessors to get it over the line.
Then of course a number of the papers in the second list - the ones that have come up most often here before - are basically just self-published. But they wouldn't have been talked about around here unless there was some quality there.
With the papers that do have key important messages, what are they ? We each possibly have different specific areas of expertise that might allow us to easily pick specific bits that are not right and also what's really important ... things that others would miss. Pickups are only kind of a peripheral area of interest for me - as I said I accumulated these references somewhat coincidentally as part of assembling a comprehensive wider collection. So I'm as interested to hear some expert assessments as the next person.
Maybe ms you could elaborate on how that section of Tillman would be improved ? And where McDonald is maybe not correct. I also recall someone questioning some of Jungmann recently. All that is kind of what a Journal Club does - pick a paper, summarize its important bits, and then dissect it. 
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Post by mikecg on Nov 20, 2023 10:43:20 GMT -5
Hello timtam, Thanks for listing your guitar pickup publications. The discussion concerning the publication of reviewed and non-reviewed work is not new, and is ongoing. If all publications were rigorously reviewed - that would make life a lot simpler for the reader, but then as you point out the quality of the review process is a variable that will remain difficult to assess, and it seems that even 'top level' reviewed papers can be misleading or even downright fraudulent! By the way, papers published in languages other than English will be of limited value for those restricted to reading in English! |
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Post by ms on Nov 20, 2023 12:51:58 GMT -5
Maybe ms you could elaborate on how that section of Tillman would be improved ? And where McDonald is maybe not correct. I also recall someone questioning some of Jungmann recently. All that is kind of what a Journal Club does - pick a paper, summarize its important bits, and then dissect it.
Sure, happy to. The problem with Tillman's analysis in the section "Effects of pickup width" is that the the aperture is determined by the width of the pole piece, not the pickup. To understand this we need to consider the answers to two questions: 1. What is the purpose of magnetizing the string?, and 2. What is the nature of this induced magnetization? The purpose is to produce magnetic flux pointing along the axis of the coil, that is perpendicular to the plane of the windings and through the coil. The magnetization flux must vary when the position of the string changes. Long thin objects, such as guitar strings, magnetize along their length. The important thing is that this magnetization points along the string, but in opposite directions towards the bridge and the nut as you move away from the pole piece. This is because magnetic field lines of the permanent magnet come out of the top of the pole piece and bend over, eventually reentering the pole piece at or near the other end. It is the component of this field along the string that magnetizes it, and you can see that it points in opposite directions towards the bridge and nut. Field lines leak out of the string progressively along it, and they return to and re-enter the string at or near the pole piece. (You can think of the magnetized string as two long thin magnets, one on each side of the pole and pointing in opposite directions.) This bending of the field lines (of the "string magnets") near the pole piece (so they can reenter the string) makes the component of the field from the string that points through the coil. This only happens at or near the pole piece, and so the aperture is about equal to the width of the pole piece. Also you can see the field lines from both "string magnets" have components through the coil that point in the same direction so that they add rather than cancel. |
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kitwn
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Post by kitwn on Nov 20, 2023 17:20:10 GMT -5
Maybe ms you could elaborate on how that section of Tillman would be improved ? And where McDonald is maybe not correct. I also recall someone questioning some of Jungmann recently. All that is kind of what a Journal Club does - pick a paper, summarize its important bits, and then dissect it.
Sure, happy to. The problem with Tillman's analysis in the section "Effects of pickup width" is that the the aperture is determined by the width of the pole piece, not the pickup. To understand this we need to consider the answers to two questions: 1. What is the purpose of magnetizing the string?, and 2. What is the nature of this induced magnetization? The purpose is to produce magnetic flux pointing along the axis of the coil, that is perpendicular to the plane of the windings and through the coil. The magnetization flux must vary when the position of the string changes. Long thin objects, such as guitar strings, magnetize along their length. The important thing is that this magnetization points along the string, but in opposite directions towards the bridge and the nut as you move away from the pole piece. This is because magnetic field lines of the permanent magnet come out of the top of the pole piece and bend over, eventually reentering the pole piece at or near the other end. It is the component of this field along the string that magnetizes it, and you can see that it points in opposite directions towards the bridge and nut. Field lines leak out of the string progressively along it, and they return to and re-enter the string at or near the pole piece. (You can think of the magnetized string as two long thin magnets, one on each side of the pole and pointing in opposite directions.) This bending of the field lines (of the "string magnets") near the pole piece (so they can reenter the string) makes the component of the field from the string that points through the coil. This only happens at or near the pole piece, and so the aperture is about equal to the width of the pole piece. Also you can see the field lines from both "string magnets" have components through the coil that point in the same direction so that they add rather than cancel. That's a great explanation ms, thanks for that. Do you have any field diagrams, links to diagrams or (even more fabulous) links to software than can generate diagrams for any given geometry? Kit |
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kitwn
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Post by kitwn on Nov 20, 2023 17:35:45 GMT -5
Thanks timtam. I've read some Lemme and have his book on electric guitar secrets plus a download of The Book from GITEC but some more light reading for the evenings will be welcome 😎. Guitar pickups remind me very much of wireless antennas, which were part of my professional activity when I still had to work for a living... Basically very simple but fiendishly complicated when you look a bit closer.
Kit
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timtam
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Post by timtam on Nov 20, 2023 20:58:18 GMT -5
.... By the way, papers published in languages other than English will be of limited value for those restricted to reading in English! Four easy translation tools have recently vastly changed my ability to utilize non-English resources ... 1. Google Translate's web site does a decent job of translating/saving whole non-English PDFs (up to 10mb IIRC; sometimes PDF compression needed to get them under that). I have recently been able to read theses in Slovenian and Polish that way ! I also use it for translating Zollner's German-only PDFs.
2. Google's right-click Translate to English in Chrome can usually translate non-English web sites well (and I find it easier to use than other web site translation options). One can read Helmuth Lemme's German site that way for example. eg 3. If one uses the free Zotero as one's PDF reference collection manager, there is a translation plugin. 4. For non-English youtube videos, one can turn on Closed Captions/Subtitles and then set Auto Translate to English. That's how I watch Zollner's and GITEC's German videos (albeit translation is sometimes not great). |
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kitwn
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Post by kitwn on Nov 21, 2023 3:09:58 GMT -5
.... By the way, papers published in languages other than English will be of limited value for those restricted to reading in English! Four easy translation tools have recently vastly changed my ability to utilize non-English resources ... 1. Google Translate's web site does a decent job of translating/saving whole non-English PDFs (up to 10mb IIRC; sometimes PDF compression needed to get them under that). I have recently been able to read theses in Slovenian and Polish that way ! I also use it for translating Zollner's German-only PDFs.
2. Google's right-click Translate to English in Chrome can usually translate non-English web sites well (and I find it easier to use than other web site translation options). One can read Helmuth Lemme's German site that way for example. eg 3. If one uses the free Zotero as one's PDF reference collection manager, there is a translation plugin. 4. For non-English youtube videos, one can turn on Closed Captions/Subtitles and then set Auto Translate to English. That's how I watch Zollner's and GITEC's German videos (albeit translation is sometimes not great). I like the GITEC site and Helmuth Lemme's work a lot. I've started looking at suitable components to implement an Arduino-controlled state-variable filter with digitally controlled potentiometers to combine with low inductance, wideband pickups in what might turn into a very versatile not-quite-a-Stratocaster guitar. Whether it ever gets off the design page and into the workshop is another matter, but the design work allows me to sit in a comfy chair and stay out of mischief in the evening after a busy day weeding the orchard and watering the veggies. |
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Post by ms on Nov 21, 2023 6:08:38 GMT -5
That's a great explanation ms, thanks for that. Do you have any field diagrams, links to diagrams or (even more fabulous) links to software than can generate diagrams for any given geometry? Kit aquin43's threads and posts in other threads are a great place to look. For example: guitarnuts2.proboards.com/thread/8530/2d-magnetised-string-simulation |
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Post by mikecg on Nov 21, 2023 7:42:33 GMT -5
.... By the way, papers published in languages other than English will be of limited value for those restricted to reading in English! Four easy translation tools have recently vastly changed my ability to utilize non-English resources ... 1. Google Translate's web site does a decent job of translating/saving whole non-English PDFs (up to 10mb IIRC; sometimes PDF compression needed to get them under that). I have recently been able to read theses in Slovenian and Polish that way ! I also use it for translating Zollner's German-only PDFs.
2. Google's right-click Translate to English in Chrome can usually translate non-English web sites well (and I find it easier to use than other web site translation options). One can read Helmuth Lemme's German site that way for example. eg 3. If one uses the free Zotero as one's PDF reference collection manager, there is a translation plugin. 4. For non-English youtube videos, one can turn on Closed Captions/Subtitles and then set Auto Translate to English. That's how I watch Zollner's and GITEC's German videos (albeit translation is sometimes not great). Hello timtam, Thanks for listing your links to some web based language translation tools. Unfortunately, I find the performance of the Google tool to be inadequate (i.e of limited value), for scientific and technical papers published in the Japanese or Chinese languages. |
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Post by ms on Nov 22, 2023 13:12:12 GMT -5
timtam asked me to comment also on the McD explanation that is first on the list places to go first in a previous post. Near the end of Section 1 there is a figure, the last figure in that section. It shows a permanent field pointing perpendicular to the string and away from the coil. This field is uniform; that is it does not vary in space as well as time. It produces string magnetization in the same direction as it points. The resulting field from this magnetization points through the coil and so produces a voltage when the string vibrates, changing the flux density through the coil. As I described earlier in the thread when describing Tillman's explanation, the field through the coil actually results from magnetization pointing along the string. This magnetization is zero right over the pole piece and points in opposite direction on opposite sides of it. It is this change that causes the component of field through the coil. McD did say that his model is simplified, but it is easy to miss what that means.
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Post by unreg on Nov 22, 2023 18:01:13 GMT -5
Unfortunately, I find the performance of the Google tool to be inadequate (i.e of limited value), for scientific and technical papers published in the Japanese or Chinese languages. try duck.com and search “translate”; then choose from detect language dropdown on the left; then paste text in that language and it will display English equivalent, unless you adjust with the English dropdown on the right |
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Post by mikecg on Nov 22, 2023 19:56:19 GMT -5
Hello unreg, Thanks - I'll try anything once - but I have my doubts - especially after my recent 'encounters' with the 'Chat GPT' and 'Bing' AI's! |
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Post by ms on Nov 23, 2023 6:56:46 GMT -5
I would like to suggest the first part of this:
What the Pickup "Sees": Its Aperture, Manfred Zollner (https://www.gitec-forum-eng.de/wp-content/uploads/2021/04/z60e_aperture_mt.pdf).
It begins with a description of why the aperture might matter, that is, the filtering out of possibly important high frequency components, and then describes an aperture measurement technique and shows the results, which can be summarized in a simple way as "in a Fender type single coil pickup, it is the diameter of the magnet that approximately defines the aperture." (This should apply in an approximate way to the steel slug or screw in a Humbuckers or P90. There is a confusing translator's note near the end of the paper which casts doubt on this, but I do not think that this note is correct.)
After the description of the measurement, the paper becomes more complicated, developing a model describing the results. This requires some physics knowledge, and I do not suggest studying it unless you have some such knowledge and a strong desire to understand how this works.
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Post by mikecg on Nov 23, 2023 14:21:36 GMT -5
Hello ms, Thanks for the link - I have downloaded the Zollner paper. |
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Post by Yogi B on Nov 26, 2023 22:23:14 GMT -5
Mustonen, M., Kartofelev, D., Stulov, A., & Valimaki, V. (2014). Experimental verification of pickup nonlinearity. Proceedings of the International Symposium on Musical Acoustics ISMA 2014. Le Mans, France. dafx2018.web.ua.pt/papers/DAFx2018_paper_39.pdf... Novak, A., Lihoreau, B., Lotton, P., Brasseur, E., & Simon, L. (2018). Experimental study of guitar pickup nonlinearity. Proceedings of the 21st International Conference on Digital Audio Effects (DAFx-18), Aveiro, Portugal. 280–287. dafx2018.web.ua.pt/papers/DAFx2018_paper_39.pdfThese two have the same URL, the first should be www.ioc.ee/~stulov/isma2014_M.pdf
Thanks for listing your links to some web based language translation tools. Unfortunately, I find the performance of the Google tool to be inadequate (i.e of limited value), for scientific and technical papers published in the Japanese or Chinese languages. At least the papers are modern enough to have been digitally typeset; making it quick to copy & paste the original text into a translator, get whatever result it gives, and move on if that's unsatisfactory. Whereas for older texts, even if the source language is something that online translators handle better, you have the extra hurdle of manually verifying and correcting OCR generated text — vastly slowing down the process. |
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timtam
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Post by timtam on Nov 27, 2023 3:16:03 GMT -5
Mustonen, M., Kartofelev, D., Stulov, A., & Valimaki, V. (2014). Experimental verification of pickup nonlinearity. Proceedings of the International Symposium on Musical Acoustics ISMA 2014. Le Mans, France. dafx2018.web.ua.pt/papers/DAFx2018_paper_39.pdf... Novak, A., Lihoreau, B., Lotton, P., Brasseur, E., & Simon, L. (2018). Experimental study of guitar pickup nonlinearity. Proceedings of the 21st International Conference on Digital Audio Effects (DAFx-18), Aveiro, Portugal. 280–287. dafx2018.web.ua.pt/papers/DAFx2018_paper_39.pdfThese two have the same URL, the first should be www.ioc.ee/~stulov/isma2014_M.pdf
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timtam
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Post by timtam on Mar 1, 2024 21:17:56 GMT -5
New MSc thesis:
Villarreal, L. A. (2023). Electromagnetic Field Analysis, Materials Characterization, and Advanced Modeling of Modern Guitar Pickups [Master of Science in Engineering, University of Texas Rio Grande Valley]. scholarworks.utrgv.edu/etd/1430
Abstract: This Thesis establishes the foundations of modern guitar pickup theory, enhancing
current pickup design by an increase in voltage output, reduction of DC resistance, and a
reduction of production costs. This research investigates factors that have received insufficient
attention, such as the performance of different magnetic materials, magnet geometry, bobbin
geometry, metal effects, etc. An equation to calculate the output of guitar pickups is developed.
Additionally, this work constructs a modern pickup using the techniques developed in this thesis
incorporating theory and advanced modeling techniques to simulate changes in performance and
interactions with different magnetic materials and geometries. The new design developed in this
study features 1200-1850 coil windings, 1.5K Ohms DC resistance, with a resulting output of
368 mV at 85.5 Hz. This work compares traditional pickups and four new experimental versions.
The research discusses the relative costs and properties of three main magnet families:
Neodymium, Ferrite, and Alnico. Neodymium magnets emerge as a promising choice, balancing
cost and performance, particularly the N52 Neodymium magnet, which results in this study
demonstrate it outperforms the industry standard Alnico 5.
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