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Post by antigua on Sept 3, 2021 22:14:14 GMT -5
The output level also depends on how close the coil is to the strings. Making the pole pieces taller means that the coil can't be raised as close to the strings as possible. I mean in Strat pickup there are quite thick, looks like 3-4mm, fiber-airgap-plastic "sandwich" between copper wire and top surface of pickup. It could be reduced to ~1mm discarding decorate plastic cup and using bobbin made from polycarbonat instead of fiber. So coil could be 2-3mm closer to strings than it is, independent from pole pieces position. Yeah that would certainly increase the output. Seymour Duncan has as pickups called the SSL-4 which makes the pole pieces and coil about as flush as possible. |
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Post by antigua on Sept 5, 2021 3:43:37 GMT -5
I think I have to take back my earlier assumption that the string is saturating, because I tried a new test tonight, where the pickup has no core and no magnet, and 100% of the magnetic source is external. The setup is like this:  I have an AlNiCo 5 pole piece sticking to one of the screws. There is a Strat pickup in there with no pole pieces, and the pickup is connected directly to a Boss wireless transmitter. This is a guitar I bought direct from China to use for experiments, so it looks a bit ugly aside from the spalted maple veneer. The first think that really surprised me is 1) how much remnant flux remains in the strings even after the magnet is removed. Audibly about half the volume, easily loud enough to be usable. And 2) the maximum of that remanence is achieved with the AlNiCo 5 pole piece is about a centimeter away from the strings. It's not even necessary to tough the magnet to the strings. To degauss the strings again, I could turn the AlNiCo 5 pole piece over and hold it about one centimeter over the string, and it would null out the existing remnant flux, and cause the voltage output to become completely inaudible. Moving the AlNiCo any closer than one centimeter merely re-polarized the strings again, with the opposite polarity. A few posts back it was mentioned that the permeability of the guitar string is most self-sustaining along the length of guitar string, and it seems that guitar string might be especially good at supporting a magnetic field due to the fact that it's long and continuous. But the more important observation is that the string didn't appear to demonstrate saturation with this setup. The voltage output continued to get higher and higher as the external magnetic becomes closer to the string, up to the point of touching the string. What that tells me is that if you have a pickup under the strings, the strings can't be saturated, there's still increasing potential for the strings to magnetize up to the point where the pickup would be touching the string. You might think that's obvious, because if you raise the pickup it gets louder and louder until it touches the strings, but maybe that could have owed to the coil being moved closer to the string, but as it turns out, it seems to be both factors are at play. I also tried this with a neodymium and got the same result, and that's important because the neodymium is not permeable, so it acts as an indiscriminate magnetic source, rather than an interactive one. The neodymium was also able to nullify the remnant flux in the string when flipped over, but at a distance of about two and a half centimeters, instead of just one centimeter. So in the previous type of test, holding the external magnet over a fully functional pickup in a way that complimented the magnetic field of the pickup, didn't result in an increased output, and it seems like a plausible explanation is because the string is moving away from one magnet and towards another at all times. The magnetic field changes from being stronger over the pickup, to becoming homogenous over the pickup. If the output doesn't increase when a second magnet is brought in from above, this must mean 1) some of the output voltage (the sum of magnetic change through the coil by time) owes to the movement of the string with it's remnant flux, and that's what's happening when there is no magnet aside from the residual magnetism of the string, and 2) additional to that, some of the voltage owes to the change of flux that comes as a result of the string oscillating near and far from a single source of magnetism. The reason why bringing a second magnet from the top doesn't increase the output is because what is gained in sum flux density, is lost by the fact that the mangetic field around the string have become homogenous. In conclusion, the string doesn't seem to be saturated, I was probably wrong about that. This experiment shed a lot of light on things. |
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VT
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Post by VT on Sept 5, 2021 5:45:47 GMT -5
In conclusion, the string doesn't seem to be saturated, Good update antigua! Time ago I tried this but noticed that flux that remains in string not stable, it become weaker after playing or in time. I am not sure enough, will check it next week. Sound is also different because there are no more Eddy currents losts (Q-factor higher). Looks like you reach here maximum remanence of this kind of steel.. P.S. By the way - what is the contraption between neck and bridge pickups? |
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Post by antigua on Sept 5, 2021 14:00:26 GMT -5
In conclusion, the string doesn't seem to be saturated, Good update antigua! Time ago I tried this but noticed that flux that remains in string not stable, it become weaker after playing or in time. I am not sure enough, will check it next week. Sound is also different because there are no more Eddy currents losts (Q-factor higher). Looks like you reach here maximum remanence of this kind of steel.. P.S. By the way - what is the contraption between neck and bridge pickups? As a matter of fact there was an guitar that had a pickup with no magnet, and the guitar came with a magnet, and you were supposed to magnetize the strings before playing, each and ever time. I have no idea what the point was, I read about in some old guitar history book, I can't remember the details, I think it was intended for an acoustic guitar and that the intention was to have a pickup that was very light weight. I remember that it was assumed the magnetic charge in the string had to be replenished often, so it came with a magnetic "wand" included. I think the magnetized domains of steel are not stable, I would guess that the strings lose remanence even at rest, but I wonder if plucking the strings also causes them to lose change. I know that AlNiCo, for example, can lose charge due to physical shock. The remnant flux is definitely maxing out, because getting a magnet closer than an inch to the strings doesn't increases the volume of the "remanence only" volume output, and then the remanence can be nulled completely from some distance away. I think it's interesting that the string doesn't saturate despite being so thin, and it really goes to show how a guitar string makes a really effective magnet due to the fact that it's long. It's also true that a pickup with an air coil has a VERY high Q factor. If you had a pickup with neo's, or any other setup that is free of eddy currents, steps would have to be taken to lower it in order to get a pleasing sound from the pickup. The strange thing in the middle is a string plucker device guitarnuts2.proboards.com/thread/8001/string-plucking-mechanism-consistent-testing . I didn't use it here, but I didn't want to remove it for the picture. If I were to do some amplitude testing, the string plucker would come in handy since it provides a near-constant string movement, but that sort of test is a lot of work to set up and conduct. |
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timtam
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Post by timtam on Feb 20, 2022 23:21:40 GMT -5
This new video came up on one of my feeds yesterday. Seems to be a good just-the-essentials, step-by-step video summary of antigua's and Willmott's procedures.
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Post by antigua on Feb 21, 2022 16:32:14 GMT -5
This new video came up on one of my feeds yesterday. Seems to be a good just-the-essentials, step-by-step video summary of antigua's and Willmott's procedures.
Wow, I'm glad someone did this. I have put a lot of work into testing pickups, but making videos is a whole other ton of work on top of that. I futz around a lot just to take simple pictures of the pickups. I can't imagine making a whole video. Really great video, I was watching for any mistakes, and I didn't see any. Maybe the only think it was missing was a summary at the end about what the purpose of a bode plot is, some discussion about eddy currents and brass versus nickel covers. But that's why I don't make videos, I would create a lot of work for myself. Maybe he will cover that in a future video. It's good a for a pickup maker to have these tools, so that if they're tasked with duplicating a pickup, they can know pretty much everything there is to know about what they're recreating, and if they're not sure what type of metal allow is used, the bode plot really helps to figure out what it is. The hardware is so cheap, about the cost of a set of boutique pickups, that I can't imagine why a pickup business wouldn't want to have this type of test suite on hand. |
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Post by stratotarts on Feb 21, 2022 19:15:58 GMT -5
Holy cow! I had no idea that was out there! That's a really useful video, and well produced.
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Post by rivetpickups on Apr 17, 2022 18:13:01 GMT -5
Great post, Antigua. You gave me some good challenges in my early days making pickups which I much appreciated and hope I'm putting to good use. Appreciate it all.
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yanyan
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Post by yanyan on May 24, 2022 11:39:59 GMT -5
As an aside, because current is induced when the magnetized strings move near and from from the pickup, the side-to-side movement of the string cannot be heard audibly, because side-to-side movement does not cause the string to become significantly nearer or further from the pickup. Therefore, even though a guitar string moves along an x and y axis above the pickup, you only ever hear the movement in relation to the y axis. This is part of what gives an electric guitar it's distinct tone.
I'm feeling like an idiot by asking this, but i'd like to understand this more. Why is current induced only by the up and down motion of the string and not the side to side? What are the implications here of string and polepiece alignment? How would this change in a rail-type pickup?
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Post by antigua on May 24, 2022 13:58:04 GMT -5
As an aside, because current is induced when the magnetized strings move near and from from the pickup, the side-to-side movement of the string cannot be heard audibly, because side-to-side movement does not cause the string to become significantly nearer or further from the pickup. Therefore, even though a guitar string moves along an x and y axis above the pickup, you only ever hear the movement in relation to the y axis. This is part of what gives an electric guitar it's distinct tone.
I'm feeling like an idiot by asking this, but i'd like to understand this more. Why is current induced only by the up and down motion of the string and not the side to side? What are the implications here of string and polepiece alignment? How would this change in a rail-type pickup?
I had this same question about six years ago, and "ms" explained it. This article explains it in very technical detail www.physics.princeton.edu//~mcdonald/examples/guitar.pdf . The way voltage is created in the pickup is through magnetic change through the pickup's coil. If you apply current to a coil, it creates a magnetic field, and a pickup works by just doing the opposite; inputting magnetism and outputting current. The magnetic field is nearly homogenous across the top of a rail pickup, so you can move the string side to side, and the net change of magnetism through the coil very nearly zero. But the magnetic field is not homogenous with respect to distance, so when the string moves nearer or further from the rail, the magnetism through the coil changes. With pole pieces, the magnetic field is not homogenous across the top, the magnetic field strength drops off with respect to both axis, so you get voltage as a result of the string moving near and far as well as side to side, but as the McDonald article explains, the voltage produced by the side to side is small compared to the voltage produced by near/far string movement, because the magnetic field strength difference is much larger from near to far compared to side to side. Also, those side to side voltages are double the frequency (one octave higher) of the near to far movement, because when the string moves near to far, there is one cycle of magnetic increase and decreased as the string makes one full trip from near to far and back, but for side to side movement, the string is passing across the magnetic axis the pole piece, and that means there are two cycles of increase and decrease as the string makes one trip back and forth. It's the fact of the string travelling across the axis that causes that doubling of the voltage cycle, the doubled octave, so if you bend the guitar string such that the side to side movement is not directly over the axis of the pole piece, then that double harmonic disappears and the side to side movement will produce the same frequency as the near to far movement. The fact that you can barely perceive a difference in sound when you bend the string away from the pole piece axis, or even notice when a guitar string is not over the pole piece axis, a testament to how low that voltage is, as is stated in the McDonald article. |
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yanyan
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Post by yanyan on May 26, 2022 8:47:48 GMT -5
I think I have to take back my earlier assumption that the string is saturating, because I tried a new test tonight, where the pickup has no core and no magnet, and 100% of the magnetic source is external. The setup is like this: I have an AlNiCo 5 pole piece sticking to one of the screws. There is a Strat pickup in there with no pole pieces, and the pickup is connected directly to a Boss wireless transmitter. This is a guitar I bought direct from China to use for experiments, so it looks a bit ugly aside from the spalted maple veneer. The first think that really surprised me is 1) how much remnant flux remains in the strings even after the magnet is removed. Audibly about half the volume, easily loud enough to be usable. And 2) the maximum of that remanence is achieved with the AlNiCo 5 pole piece is about a centimeter away from the strings. It's not even necessary to tough the magnet to the strings. To degauss the strings again, I could turn the AlNiCo 5 pole piece over and hold it about one centimeter over the string, and it would null out the existing remnant flux, and cause the voltage output to become completely inaudible. Moving the AlNiCo any closer than one centimeter merely re-polarized the strings again, with the opposite polarity. A few posts back it was mentioned that the permeability of the guitar string is most self-sustaining along the length of guitar string, and it seems that guitar string might be especially good at supporting a magnetic field due to the fact that it's long and continuous. But the more important observation is that the string didn't appear to demonstrate saturation with this setup. The voltage output continued to get higher and higher as the external magnetic becomes closer to the string, up to the point of touching the string. What that tells me is that if you have a pickup under the strings, the strings can't be saturated, there's still increasing potential for the strings to magnetize up to the point where the pickup would be touching the string. You might think that's obvious, because if you raise the pickup it gets louder and louder until it touches the strings, but maybe that could have owed to the coil being moved closer to the string, but as it turns out, it seems to be both factors are at play. I also tried this with a neodymium and got the same result, and that's important because the neodymium is not permeable, so it acts as an indiscriminate magnetic source, rather than an interactive one. The neodymium was also able to nullify the remnant flux in the string when flipped over, but at a distance of about two and a half centimeters, instead of just one centimeter. So in the previous type of test, holding the external magnet over a fully functional pickup in a way that complimented the magnetic field of the pickup, didn't result in an increased output, and it seems like a plausible explanation is because the string is moving away from one magnet and towards another at all times. The magnetic field changes from being stronger over the pickup, to becoming homogenous over the pickup. If the output doesn't increase when a second magnet is brought in from above, this must mean 1) some of the output voltage (the sum of magnetic change through the coil by time) owes to the movement of the string with it's remnant flux, and that's what's happening when there is no magnet aside from the residual magnetism of the string, and 2) additional to that, some of the voltage owes to the change of flux that comes as a result of the string oscillating near and far from a single source of magnetism. The reason why bringing a second magnet from the top doesn't increase the output is because what is gained in sum flux density, is lost by the fact that the mangetic field around the string have become homogenous. In conclusion, the string doesn't seem to be saturated, I was probably wrong about that. This experiment shed a lot of light on things.
Wow. This IS interesting!
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yanyan
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Post by yanyan on May 26, 2022 8:59:24 GMT -5
I'm feeling like an idiot by asking this, but i'd like to understand this more. Why is current induced only by the up and down motion of the string and not the side to side? What are the implications here of string and polepiece alignment? How would this change in a rail-type pickup?
I had this same question about six years ago, and "ms" explained it. This article explains it in very technical detail www.physics.princeton.edu//~mcdonald/examples/guitar.pdf . The way voltage is created in the pickup is through magnetic change through the pickup's coil. If you apply current to a coil, it creates a magnetic field, and a pickup works by just doing the opposite; inputting magnetism and outputting current. The magnetic field is nearly homogenous across the top of a rail pickup, so you can move the string side to side, and the net change of magnetism through the coil very nearly zero. But the magnetic field is not homogenous with respect to distance, so when the string moves nearer or further from the rail, the magnetism through the coil changes. With pole pieces, the magnetic field is not homogenous across the top, the magnetic field strength drops off with respect to both axis, so you get voltage as a result of the string moving near and far as well as side to side, but as the McDonald article explains, the voltage produced by the side to side is small compared to the voltage produced by near/far string movement, because the magnetic field strength difference is much larger from near to far compared to side to side. Also, those side to side voltages are double the frequency (one octave higher) of the near to far movement, because when the string moves near to far, there is one cycle of magnetic increase and decreased as the string makes one full trip from near to far and back, but for side to side movement, the string is passing across the magnetic axis the pole piece, and that means there are two cycles of increase and decrease as the string makes one trip back and forth. It's the fact of the string travelling across the axis that causes that doubling of the voltage cycle, the doubled octave, so if you bend the guitar string such that the side to side movement is not directly over the axis of the pole piece, then that double harmonic disappears and the side to side movement will produce the same frequency as the near to far movement. The fact that you can barely perceive a difference in sound when you bend the string away from the pole piece axis, or even notice when a guitar string is not over the pole piece axis, a testament to how low that voltage is, as is stated in the McDonald article.
I read and re-read that PDF as well as other references, including the Tillman ones, in earnest. My bruised brain (dammit Jim, i'm a programmer, not a physicist/mathematician!) came up with more questions:
1. Just to clarify: the y movement of the string ALSO generates higher harmonics, right?
2. If there was a way to sense more of the harmonics generated by the side-to-side movement, wouldn't that result in a richer-sounding (subjective adjective alert) pickup? Or a trebly one?
3. Given width w of the coil, can we determine how far B0 extends beyond w? Based on magnet strength? What is the minimum distance beyond w for the 1st and 6th strings at which V(t) would start to decrease?
4. I'm curious about the line, "Furthermore, if the wire is close to the pickup coil such that h = w/sqrt(12), the 2nd harmonic pickup of the x vibration is suppressed." From experience with adjusting pickup heights, lowering the pickup (thus increasing the 2nd harmonic) makes the tone more bassy. Shouldn't the tone become more trebly instead? By the way, where'd that figure 12 come from?
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Post by ms on May 26, 2022 10:19:51 GMT -5
The strength of the McDonald analysis is that it shows you how the equations of E&M describe how a signal voltage is generated in a guitar pickup. The assumption of a constant B field pointing perpendicular to the face of the pickup is not right. In fact, it is one of those "spherical cow" assumptions that physicists are supposed to be fond of making. (We all know that cows are rectangular so that they can pack in cartons of milk more efficiently.)
A guitar string is long and thin with a relative permeability typical of high carbon steel, about 100. Such a structure magnetizes almost exclusively along its length if there is a component of the driving field in that direction. The field from the pole piece bends over as it emerges from it, and so there is. Notice that the magnetization flips direction right over the pole piece, and is zero right over the center. It is this change in magnetization that generates the component of the field that points through the pickup coil.
The sampling width of the pickup is about equal to the diameter of the pole piece, not the width of the pickup as many assume for convenience.
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Post by antigua on May 26, 2022 15:49:24 GMT -5
I read and re-read that PDF as well as other references, including the Tillman ones, in earnest. My bruised brain (dammit Jim, i'm a programmer, not a physicist/mathematician!) came up with more questions:
1. Just to clarify: the y movement of the string ALSO generates higher harmonics, right?
2. If there was a way to sense more of the harmonics generated by the side-to-side movement, wouldn't that result in a richer-sounding (subjective adjective alert) pickup? Or a trebly one?
3. Given width w of the coil, can we determine how far B0 extends beyond w? Based on magnet strength? What is the minimum distance beyond w for the 1st and 6th strings at which V(t) would start to decrease?
4. I'm curious about the line, "Furthermore, if the wire is close to the pickup coil such that h = w/sqrt(12), the 2nd harmonic pickup of the x vibration is suppressed." From experience with adjusting pickup heights, lowering the pickup (thus increasing the 2nd harmonic) makes the tone more bassy. Shouldn't the tone become more trebly instead? By the way, where'd that figure 12 come from?
1) the y movement doesn't produce any artificial harmonic content like the x movement over an axis does, but there are higher harmonics present based on the movement of the guitar string itself, for example when you do a pinch harmonic, you can hear those harmonics in your ear, and they're picked up by the pickup, where as the double harmonic of the x movement is something that the pickup causes to happen due to geometrical alignment, and can't be heard if the guitar isn't plugged into an amp. 2) Adding some proportion of second harmonic of the fundamental doesn't change the timbre much at all, it's just one octave higher than the fundamental. When you play an octave on two guitar strings, it does sound rich, but that's because of intermodulation causing beating, which sounds lively, but the octaves coming off a single guitar string are all synchronous, and it just sounds like more mids or more treble. It's like the difference between a neck and bridge pickup, but far more subtle than that. Like I said above, if you bend the string away from the center axis of the pole that it's over, the double harmonic goes away, so it's easy to hear for yourself, and it's somewhere between barely and not perceptible. 3) The magnetic field shape stays the same no matter the field strength. That's something else I asked ms a while ago. I'm not that great at math actually, I barely understand it myself, but as ms says, the model is an approximation, and I think you can get a more pragmatic result by bending the string away from the pole piece and making note of the volume drop. 4) It's saying that if the string is close enough the pole piece, the pole piece acts like a rail in terms of producing a homogenous magnetic field, but I think that McDonald is presuming the pole piece, represented as "w", is not circular. With a real pole piece, because it's a cylinder, it will never have a homogenous field above it, like a rail does, at any distance, because by definition something which is round is not linear, where as a rail is obviously linear. |
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nienturi
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Post by nienturi on Feb 20, 2024 0:40:41 GMT -5
Determining flux density at the poles and stringsOne major aspect of a guitar's function that is not addressed by the driver coil is the amount of flux change / voltage the pickup is able to acquire from the moving guitar strings. The more powerfully the pickup can charge the strings, the more flux change will occur within the coils, and the more voltage will be generated. Certain grades of AlNiCo, as well as certain magnetic assemblies made out of steel (PAF humbucker) will produce more or less flux density at the strings. Aside from voltage output, another reason to observe the flux density of a pickup is to determine how much magnetic pull can be expected between the pickup and the guitar strings. For example, AlNiCo 5 pole pieces in Strat pickup usually measure a very high strength of ~1050 Gauss, and these pickups are known to cause unpoleasent sounds when they are set too close to the guitar strings, especially the thicker wound strings. In order to determine how much flux density the pickup has to offer the guitar strings at the pole tops, you need a magnetometer. The Spin Doctor magnetometer is commonly used by pickup testers gravitastech.weebly.com/spin-doctor.html , and costs just under $100. This type of magnetometer exploits a Hall effect sensor in order to measure flux density. The Spin Doctor is no longer being produced, but there are similarly priced alternatives, such as the WT10A , which shows values in milliteslas. To convert milliteslas to Gauss, just multiple the value by 10. 100mT = 1000G. Also make note that twice the flux density, as might be seen between AlNiCo 2 and AlNiCo 5, does not mean twice the generated voltage, since there is not a linear relationship between voltage and remnant flux density, but rather the voltage owes to the rate of flux change through the coil, as the string moves, and these two things don't have a linear relationship. Doubling the magnetic flux might only increase the voltage by about 15%, based on observational data. The voltage output will also increase if the pickup's pole pieces have a higher permeability, because this higher permeability increases the overall flux change as well. Therefore, a pickup with a strong AlNiCo pole piece may generate less voltage than a pickup with steel pole pieces and a weaker overall magnetic field, because the permeability of the steel pole pieces nevertheless increases the overall flux change as the guitar string moves nearer and further. As mentioned in the first paragraph, a more useful take away might be how the pickup's magnetic pull effects the guitar string. At it's most extreme, it can cause "Stratitus", or "wolf tones" which is an easily audible inter-modulation and beating of two frequencies that are close together, but even at the non extremes, experiment shows that even minor changes in magnetic pull changes the output waveform as the guitar string's energy decays, and in my opinion, when the differences between magnets are discussed, it's the difference in how the magnet pulls upon the guitar string that is being spoken of. Hi Antigua. I have a question about the approach on the flux measurement. I have recently bought a gaussmeter so that i can use that data on my pickup evaluations & my reviews. How do you get only one value like "screw250G/slug 280G" because i read more non uniform values. For example last night i measured those data from my 8,5K Pearly Gates; Slug=from low-E to hi-e 234 - 268 - 270 - 248 - 253 - 227 Screw=from low-E to hi-e 272 - 248 - 250 - 279 - 265 - 265 So do you calculate the arithmetic mean like 250G for slug and 263 for the screw coil? Or measuring on spesific point like "data of the pole piece top of G string only"? Thank you so very much  |
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Post by antigua on Feb 20, 2024 1:54:12 GMT -5
Hi Antigua. I have a question about the approach on the flux measurement. I have recently bought a gaussmeter so that i can use that data on my pickup evaluations & my reviews. How do you get only one value like "screw250G/slug 280G" because i read more non uniform values. For example last night i measured those data from my 8,5K Pearly Gates; Slug=from low-E to hi-e 234 - 268 - 270 - 248 - 253 - 227 Screw=from low-E to hi-e 272 - 248 - 250 - 279 - 265 - 265 So do you calculate the arithmetic mean like 250G for slug and 263 for the screw coil? Or measuring on spesific point like "data of the pole piece top of G string only"? Thank you so very much Nothing fancy, I just measure the center of the D and G poles and come up with an average, to the nearest 25G. The edges of the pole pieces often show a higher Gauss value, but I stick with the centers. Based on what you measured I would round it off to 250G. The flux density with a PAF / P-90 sized bar manet is a lot less consistent that people realize. Not only do you get a random assortment of values from the pole tops, but if you remove the magnet, and run the probe along the long edges of the magnet, you will find that the Gauss varies along the magnet itself, sometimes even more than the pole and screw tops do. The screws and poles actually serve to even out inconsistency in the magnet itself, by combining the flux density of weaker and strong parts of the AlNiCo bar into the steel, which has a higher permeability, and better metallurgic consistency than AlNiCo. |
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timtam
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Post by timtam on Feb 20, 2024 2:25:18 GMT -5
I'm reminded of Zollner's examples ... |
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nienturi
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Post by nienturi on Feb 20, 2024 8:20:11 GMT -5
Hi Antigua. I have a question about the approach on the flux measurement. I have recently bought a gaussmeter so that i can use that data on my pickup evaluations & my reviews. How do you get only one value like "screw250G/slug 280G" because i read more non uniform values. For example last night i measured those data from my 8,5K Pearly Gates; Slug=from low-E to hi-e 234 - 268 - 270 - 248 - 253 - 227 Screw=from low-E to hi-e 272 - 248 - 250 - 279 - 265 - 265 So do you calculate the arithmetic mean like 250G for slug and 263 for the screw coil? Or measuring on spesific point like "data of the pole piece top of G string only"? Thank you so very much Nothing fancy, I just measure the center of the D and G poles and come up with an average, to the nearest 25G. The edges of the pole pieces often show a higher Gauss value, but I stick with the centers. Based on what you measured I would round it off to 250G. The flux density with a PAF / P-90 sized bar manet is a lot less consistent that people realize. Not only do you get a random assortment of values from the pole tops, but if you remove the magnet, and run the probe along the long edges of the magnet, you will find that the Gauss varies along the magnet itself, sometimes even more than the pole and screw tops do. The screws and poles actually serve to even out inconsistency in the magnet itself, by combining the flux density of weaker and strong parts of the AlNiCo bar into the steel, which has a higher permeability, and better metallurgic consistency than AlNiCo. Thank you so very much. Not in your level but i measure the pickups as much as i can do as a hobbiest and non-electrical background person I ask that in order to have same kind of methodology by measuring. So what did i do is pretty much like you. Take the middle values, calculate the arithmetic mean but i don't round it up. 250G and 260G may not mean anything by hearing but as an engineer i can't control myself |
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nienturi
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Post by nienturi on Feb 20, 2024 8:21:37 GMT -5
I'm reminded of Zollner's examples ... Thank you very much about the graph. I have some bar magnets in the closet. I'll do a mapping tonight or tomorrow. |
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Post by antigua on Feb 20, 2024 14:21:07 GMT -5
Thank you so very much. Not in your level but i measure the pickups as much as i can do as a hobbiest and non-electrical background person I ask that in order to have same kind of methodology by measuring. So what did i do is pretty much like you. Take the middle values, calculate the arithmetic mean but i don't round it up. 250G and 260G may not mean anything by hearing but as an engineer i can't control myself I'd say I hear the softness in a APF clone that measures around 200 versus the bite of one that measures 400 or higher, but beyond that I'm not certain if I hear a difference in magnetism, or a difference in resonant peaks. One time I did do the magnet swap test, this was almost ten years ago now. It was one of things I tested, because magnet swapping was (and is) all the rage in the PAF woowoo scene. To me, AlNiCo 2, 3 and 5 were all the same, but when I switched in the AlNiCo 8 and the ceramic, it definitely took on a sharper sound. I think the specific Gauss values are mostly trivial, especially when you consider that nobody will have their pickups set to an agreed upon height. If a pickup has an especially low Gauss, it just means that it will not offer that "close" sound, but if the pickup has a higher Gauss, then you have a range of choice by lowering the pickup away from the strings. Most guitarists probably wouldn't admit it, but the pickup height has aesthetic value to it, it doesn't look right to have the pickups too high or too low. A specific Gauss can let you achieve a certain degree of magnetic strength, while also having the pickup where you want it for the picture perfect look. |
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nienturi
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Tone Journey
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Post by nienturi on Feb 26, 2024 0:48:53 GMT -5
Not only do you get a random assortment of values from the pole tops, but if you remove the magnet, and run the probe along the long edges of the magnet, you will find that the Gauss varies along the magnet itself, sometimes even more than the pole and screw tops do. The screws and poles actually serve to even out inconsistency in the magnet itself, by combining the flux density of weaker and strong parts of the AlNiCo bar into the steel, which has a higher permeability, and better metallurgic consistency than AlNiCo. I did that test and i must admit how surprised i am. I have several A5, A2s, a few A8s and some ceramics at home. And yes alnicos differ a lot. One of them has very different values from north to south; If you were to evaluate based solely on values, you would think one side is Alnico 2 and the other side is Alnico 5. Ceramics and Neodymiums are much more consistent. |
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