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Thread: Is it possible to accurately describe the tone of magnets and/or pickups?

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    Junior Member Tone Cam's Avatar
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    Is it possible to accurately describe the tone of magnets and/or pickups?

    I have been trying to come up with a system for describing the tonal properties of magnets of the same alloy that come from different suppliers. It is obvious that a variable describing overall EQ (bright vs. dark, or bass,middle,treble balance) is needed and a second variable that quantifies the density of harmonics (fat vs thin?) would be useful. It also seems important to have a variable that describes how smooth or harsh the tone is at high frequencies and possibly a fourth that deals with how open (vs. compressed) the tone is.

    It would also be useful to have a similar system for pickup tone. A few established pickup makers have attempted to describe their products with variables like EQ, output level and 'attack' but these descriptions seem to leave out a lot of important tonal information.

    Is it possible to accurately describe the tone of magnets and/or pickups with a few (<6) key variables?

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    Bent Member Chuck H's Avatar
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    Quote Originally Posted by Tone Cam View Post
    A few established pickup makers have attempted to describe their products with variables like EQ, output level and 'attack' but these descriptions seem to leave out a lot of important tonal information.
    What's left out? I'm sure there's the consideration of what real life guitar players can cognate I suppose they could include "relative to a typical PAF" or something to add scale to the image?

    FWIW I've never thought that the typical bass, mid, treble references were adequate for describing pickups. I really think you'd need AT LEAST six bands of eq AND a relative scale to known pickups if "I" were going to get my head around what it might sound like. But again, try that with Jhonny Rocker in his living room studio playing into a POD, Sansamp or Line 6. The typical demographic for these products gets confused when you say things like "upper midrange", "higher treble frequencies" or any expression that uses the abbreviation Hz. As a result I don't think there's going to be much outside of what people (likely people here on this forum) that own spectrum analyzers and such have tested for themselves. It'll be a small list. If "I" owned a spectrum analyzer and tested every pickup I've used in my life it would be a small list. But I'm an amp guy and not a pickup guy. But my point is that it's a tall order. Though like you I wish it weren't.

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    Quote Originally Posted by Tone Cam View Post
    It would also be useful to have a similar system for pickup tone. A few established pickup makers have attempted to describe their products with variables like EQ, output level and 'attack' but these descriptions seem to leave out a lot of important tonal information.
    Well, some of the "missing tonal information"...is going to have to do with the guitar the pickups are installed in, among others the scale length, pot values, the type of bridge, string length behind the saddles, the pickup's location relative the the strings both vertically and horizontally, and that's before you get into the shadier areas of 'tonewood' or the even shadier artistic intentions of the musician with said pickup. Fo'shuh some of those variables you can describe objectively, but there are far too many combinations for the pickup maker to take into account when describing their product. As Chuck says, is is down to the 'real life guitar player' to fill up those holes in the text and make an educated guess at what he's going to get in the end. And we haven't even talked about amps yet.

    A pickup maker who states his pickup is the sole factor in the player's tone and says 'it'll give you this at 2.5k Hz' is either misguided or a crook of some kind. The best he/she can do is to quantify how much he/she can't predict, and live with it. The players have to live with it too. And most of the time they do

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    Junior Member Tone Cam's Avatar
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    Thanks for the inputs - they indicate that I need to provide some background and restate my question in clearer terms.

    While every element of a player's setup affects the tone that he gets from his amp, it is possible to isolate the contribution from the pickup magnets by holding all of the variables, with the exception of the magnets, constant. Those who have made accurate tone samples of different pickup models know how to control everything that is downstream from the pickup and experienced winders can control the variables in their winding setup well enough to make a few test samples that have coils with similar tonal properties.

    Assuming that all the variables affecting tone except the Alnico 5 pole pieces in a set of Formvar-wound, strat-style single coil pickups are held essentially constant, the tonal properties of different magnets can be compared by winding a series of pickups, sequentially mounting them in the same guitar, adjusting string height, etc. to predetermined values and plugging them into a test amp that has been warmed up long enough for its tone to stabilize before each test. Performing this test with Alnico 5 pole pieces from the 6+ magnet vendors that have been discussed in other threads on this site, will yield 6+ tones that are, in some cases, significantly different from each other.

    I believe that it would be useful to have a clear way to describe these differences - both in discussions on this forum and in explaining to luthiers and musicians the tradeoffs associated with putting different magnets in their pickups. I further believe that the descriptions need use variables that describe tonal qualities as perceived by a human observer rather than numerical parameters that can be measured with an LCR meter, scope or spectrum analyzer.

    So - to restate my original question in clearer terms:

    Is it possible to describe the tonal qualities of different magnets using a few (<6) perceptual variables?? If so, what variables would you use????

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    When comparing PU magnets, everything else should be kept the same. Thus it may be a good idea to charge all magnets to be compared to a similar Gauss level.
    There is indication that magnet strength on its own has some sound influence.

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    Junior Member Tone Cam's Avatar
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    That is clearly the case - just forgot to put it into the list of variables. Several well-known pup makers advertise models with 'degaussed' magnets.

    I think that there are two effects:

    1. The interaction of the poles and strings changes and
    2. The small loop hysteresis losses vary with position on the demagnetization curve.

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    Quote Originally Posted by Tone Cam View Post
    I have been trying to come up with a system for describing the tonal properties of magnets of the same alloy that come from different suppliers. It is obvious that a variable describing overall EQ (bright vs. dark, or bass,middle,treble balance) is needed and a second variable that quantifies the density of harmonics (fat vs thin?) would be useful. It also seems important to have a variable that describes how smooth or harsh the tone is at high frequencies and possibly a fourth that deals with how open (vs. compressed) the tone is.

    It would also be useful to have a similar system for pickup tone. A few established pickup makers have attempted to describe their products with variables like EQ, output level and 'attack' but these descriptions seem to leave out a lot of important tonal information.

    Is it possible to accurately describe the tone of magnets and/or pickups with a few (<6) key variables?
    The actual difference that is made is in terms of how much the pickups pulls on the strings magnetically. The effect can't be summed up with typical tone words because the changes vary depending on which position the pickup is in, and they vary by how far the pickup is set from the strings, and the changes differ by harmonic level. The string is divided up into harmonics nodes and anti nodes, and so the harmonic effects depends on how close the pulling force is to an anti-node, and how strong the magnetic pull happens to be. The more pull there is at an anti-node, the more that specific harmonic will be disrupted. The strong the pull, the complicated things get. Because there is so much change at different harmonic levels, it's almost more of a difference in timbre than it is tone, and timbre is much harder to describe, like describing the difference between a piano and an acoustic guitar.

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    Quote Originally Posted by Antigua View Post
    The actual difference that is made is in terms of how much the pickups pulls on the strings magnetically. The effect can't be summed up with typical tone words because the changes vary depending on which position the pickup is in, and they vary by how far the pickup is set from the strings, and the changes differ by harmonic level. The string is divided up into harmonics nodes and anti nodes, and so the harmonic effects depends on how close the pulling force is to an anti-node, and how strong the magnetic pull happens to be. The more pull there is at an anti-node, the more that specific harmonic will be disrupted. The strong the pull, the complicated things get. Because there is so much change at different harmonic levels, it's almost more of a difference in timbre than it is tone, and timbre is much harder to describe, like describing the difference between a piano and an acoustic guitar.
    Also, it is how and where you strum relative to the turned on pickups(s). Guitars typically have a second harmonic peak for the first part of the initial attack and this can be controlled by pick thickness and picking style sort of like the subtle sounds made by speech and singing. Strings are just another type of vocal cord. Once the strings rotate from their initial horizontal motion through the strum, the strings will rotate to their normal motion and the initial second harmonic of sideways motion will get less as the string starts to decay.

    The only truly scientific way to test this is to automatically pick the string in the same place relative to the pickup and change pickups and magnets and compare the observable differences and then what you hear. String damping, even by a small amount, can be heard as a loss in sustain even if the pickup is not turned on.

    Joseph J. Rogowski

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    Last edited by bbsailor; 08-06-2018 at 11:33 PM.

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    Supporting Member John_H's Avatar
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    Is it possible to accurately describe the tone of magnets and/or pickups?
    With all of the variables already discussed, it's pretty easy to recognize that any measurements taken would be questionable. Tone is subjective, but describing tone in it's basics isn't difficult. Describing in accurate terms the differences between Brand X, and Brand Z's A5 humbucker bar magnets wouldn't be so easy. Start with the hard data that you can measure. Take accurate measurements, and gauss readings. I'm sure there are some differences.

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    Junior Member Tone Cam's Avatar
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    I appreciate the suggestions but don't think folks have a clear understanding of what I am asking.

    I made some quick measurements on single isolated Alnico pole pieces that will address some of the comments. The pole pieces measure 0.187 (+/- .001) x 0.671 and have very different tonal properties. I have made a number of Strat sets (with similar winding parameters) from each material and gotten feedback on their tonal properties both professional and amateur musicians. At the present time the most skilled blues player I know (over 45 years of professional experience) has neck and middle pickups from each material in two hybrid (tele bridge and strat neck/middle) teles. He likes both, recognizes that there are significant differences in their tonal properties but is unable to describe the differences beyond saying that one of the materials "sounds more like a 57 strat" than the other.

    My measurements show the difference in field strength between the two fully magnetized poles to be less than 5% and I find it hard to believe this difference to be large enough to account for the nature and size of the tonal differences between the two materials.

    This conclusion is further supported by an experiment in which I added a 0.032 thick x 0.188 dia. unmagnetized disc of Alnico 3 to the bottom of one pole and repeated the field measurement. The disc had virtually no effect on field strength even though past experience has shown that attaching them to the bottom pole surfaces of a fully magnetized strat pickup will significantly alter its tone.

    All the available experimental evidence (and I have accumulated a lot over the past 9 years) indicates that the tonal differences that are observed in samples of the same alloy from different manufacturers are due to variations in ferromagnetic loss. These losses also contribute significantly to observed tonal differences in the soft ferromagnetic materials that are commonly used to make humbucker slugs, screws and keeper bars. In all cases they are sensitive functions of composition, the methods used to cast the materials, and the details of their thermal and mechanical histories. Samples from different foundries vary significantly with respect to one or more of these parameters.

    I don't think it is possible ( or reasonable) to measure the differences in ferromagnetic loss directly but do think it should be possible to describe their effect on pickup tone using reasonably precise terminology. Terms such as 'like a PAF' or 'similar to a '57 strat' get used a lot but have poorly defined meanings.

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    Last edited by Tone Cam; 08-07-2018 at 03:56 AM. Reason: typos

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    Old Timer J M Fahey's Avatar
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    Quote Originally Posted by Tone Cam View Post
    So - to restate my original question in clearer terms:

    Is it possible to describe the tonal qualities of different magnets using a few (<6) perceptual variables??
    Very short answer?: no.
    For the very good reason that nobody knows what those variables would be.
    If so, what variables would you use????
    Dunno, you tell us, itīs your theory and investigation.
    I appreciate the suggestions but don't think folks have a clear understanding of what I am asking.
    You donīt seem to have a clear understanding either, your question is still too vague and undefined.
    I made some quick measurements on single isolated Alnico pole pieces that will address some of the comments. The pole pieces measure 0.187 (+/- .001) x 0.671 and have very different tonal properties.
    Well, you say so and I believe you, and probably *listening* to them we could find differences ... or not .... but if not even you can describe differences clearly ..... what can we do at the other end of a screen?
    I have made a number of Strat sets (with similar winding parameters) from each material and gotten feedback on their tonal properties both professional and amateur musicians. At the present time the most skilled blues player I know (over 45 years of professional experience) has neck and middle pickups from each material in two hybrid (tele bridge and strat neck/middle) teles. He likes both, recognizes that there are significant differences in their tonal properties but is unable to describe the differences beyond saying that one of the materials "sounds more like a 57 strat" than the other.
    Ok. If even such an experienced player, who *uses* them, can not describe differences, and to boot only by the vaguest most undefined and unmeasurable terms, what do you expect us to do?
    And you want us to come up with 5 or 6 variables? Wow!!!!

    My measurements show the difference in field strength between the two fully magnetized poles to be less than 5% and I find it hard to believe this difference to be large enough to account for the nature and size of the tonal differences between the two materials.
    Doubt that is the only difference and everything else is exactly the same.

    This conclusion is further supported by an experiment in which I added a 0.032 thick x 0.188 dia. unmagnetized disc of Alnico 3 to the bottom of one pole and repeated the field measurement. The disc had virtually no effect on field strength even though past experience has shown that attaching them to the bottom pole surfaces of a fully magnetized strat pickup will significantly alter its tone.
    Ok, keep experimenting.
    Use different magnets: a whole one, another 90:10 , another 80:20 , and so on, make a table showing results, then make an hipothesis and verify it with further experiments. Thatīs the Scientific method.

    [QUOTE]All the available experimental evidence (and I have accumulated a lot over the past 9 years) indicates that the tonal differences that are observed in samples of the same alloy from different manufacturers are due to variations in ferromagnetic loss.
    Ok. so you do have a Theory.
    Now experiment and confirm/discard/correct it. Thatīs the way to go.
    These losses also contribute significantly to observed tonal differences in the soft ferromagnetic materials that are commonly used to make humbucker slugs, screws and keeper bars. In all cases they are sensitive functions of composition, the methods used to cast the materials, and the details of their thermal and mechanical histories. Samples from different foundries vary significantly with respect to one or more of these parameters.
    Cool, now repeat experiments but show results in table form.
    Otherwise itīs only light talk.
    I don't think it is possible ( or reasonable) to measure the differences in ferromagnetic loss directly
    Hey!!! WHY not!!!
    If itīs the basis of your Theory, then you MUST experiment changing that variable and showing results in a table form.
    but do think it should be possible to describe their effect on pickup tone using reasonably precise terminology.
    No "terminology" will ever be more precise than actual measurements, whth results shown in an ordered/compiled form.
    Terms such as 'like a PAF' or 'similar to a '57 strat' get used a lot but have poorly defined meanings.
    You bet, and thatīs exactly my point, glad you agree.

    I suggest you continue with your experiments, and show results in an ordered way.

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    In a way, I actually see value in your blues player friend's feedback. Without any absolute measurement, tone is more efficiently compared than described. When mixing a track, you often see experienced sound engineers using an already mixed track as reference point, because they know that even their ears aren't a 100% reliable after listening to a work in progress many times. Some mixes aren't objectively harsh, they are only so compared to other mixes. One gets used to hearing certain types of sound, which is related to musical genre, what gear was available and what was fashionable at that time, etc. So in a way, your friend is giving you the most honest and accurate answer possible.

    As for investigating the impact of using magnets from different manufacturer on the 'tone', as JM Fahey suggests, you would have to repeat the tests a few dozen times to get any results of scientific value, but there are still far too many variables to take into account, at least far more than six. You would also have to compare magnet samples from the each manufacturer with themselves to test the internal variations of their production.

    This is all written from the humble point of view of a guy whose scientific background is that of a 'soft' science, ie. psychology. There are lots of guys here who come from 'harder' sciences who I'm sure will be more to the point. But in a way, the study of the human mind feels as slippery a terrain as that of tone. One can either look into a phenomenon with one's common sense & inductive processes, which are not without worth as they will be close to the thinking of the consumer, or study that phenomenon with a proper experimental framework, which takes time and resources. There is sadly not much value to anything in between those two and it can become very depressing to realize you've spent a lot of time, money and efforts on a biased experiment. We're not saying you can't do it, we're just saying that you need to do it very carefully and understand what such a study entails.

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    The small loop hysteresis losses vary with position on the demagnetization curve.
    I am not sure about this. Is there any measurement data or literature supporting this? Generally the losses caused by magnets are very low, especially in relation to other causes. And the recoil permeability doesn't change much with charge.

    But there are also other effects:

    - Professor Zollner found that PU aperture is influenced by the field strength at the strings' positions. Higher fields shorten the aperture, which allows higher string harmonics to be picked up.
    - I found that replacing the weak magnets (450G) in a P-90 type PU by stronger ones (700G) reduced the PU's inductance by over 10%.

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    Quote Originally Posted by epizootics View Post
    In a way, I actually see value in your blues player friend's feedback. Without any absolute measurement, tone is more efficiently compared than described.
    You can have an absolute measurement in the form of FFT analysis, in a controlled setting. It's not that it can't be done, it's that very few people ever have done it. I've done some testing of this sort, and witnessed that magnetic strength causes variations at different harmonic levels, and that the differences were not linear, which is to say that when the magnet is stronger, you don't just get "more" of something, but entirely different effects emerge at different harmonic levels, depending on the degree of disruption caused by the magnet. At one extreme, the string ring naturally as if there was no pickup in the guitar, while at the other, you get "wolf tones" or "Stratitus", and then there is everything in between, which constitutes the various "flavors" you get with different magnets and different pickup height settings.

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    Quote Originally Posted by Tone Cam View Post
    I made some quick measurements on single isolated Alnico pole pieces that will address some of the comments. The pole pieces measure 0.187 (+/- .001) x 0.671 and have very different tonal properties. I have made a number of Strat sets (with similar winding parameters) from each material and gotten feedback on their tonal properties both professional and amateur musicians. At the present time the most skilled blues player I know (over 45 years of professional experience) has neck and middle pickups from each material in two hybrid (tele bridge and strat neck/middle) teles. He likes both, recognizes that there are significant differences in their tonal properties but is unable to describe the differences beyond saying that one of the materials "sounds more like a 57 strat" than the other.
    These observations are not solid enough to be actionable. In order to derive an objective conclusion from a survey, you need a lot more than one source of feedback, so that it can be said that what you conclude is true of many different people, and not one person. Also, if you're testing magnetic effects, it would be crucial that absolutely everything else is controlled, meaning the same coil is used, and the height of the pickup in relation to the strings never changes. In general, it is so difficult to assure that all of these things are accounted for that it's not merely enough to say that you have accounted for them, I'd expect a detailed description of the process by which you accounted for them. If you do none of this, then in all likelihood there will be some experimenter's bias at play, and I can only assume that the outcome you report is the outcome you had wanted from the beginning.

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    You could do "waterfall" plots of the same pickup with different mags installed and see if you can "see" any differences in the plots. You would need identical plucks.

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    Magnets do not have tonal properties; they have magnetic and electrical properties, which contribute to the sound of the pickup in combination with the other components of the pickup. For example they have a magnetic field strength, electrical conductivity, and magnetic permeability.

    Quote Originally Posted by Tone Cam View Post
    I appreciate the suggestions but don't think folks have a clear understanding of what I am asking.

    I made some quick measurements on single isolated Alnico pole pieces that will address some of the comments. The pole pieces measure 0.187 (+/- .001) x 0.671 and have very different tonal properties. I have made a number of Strat sets (with similar winding parameters) from each material and gotten feedback on their tonal properties both professional and amateur musicians. At the present time the most skilled blues player I know (over 45 years of professional experience) has neck and middle pickups from each material in two hybrid (tele bridge and strat neck/middle) teles. He likes both, recognizes that there are significant differences in their tonal properties but is unable to describe the differences beyond saying that one of the materials "sounds more like a 57 strat" than the other.

    My measurements show the difference in field strength between the two fully magnetized poles to be less than 5% and I find it hard to believe this difference to be large enough to account for the nature and size of the tonal differences between the two materials.

    This conclusion is further supported by an experiment in which I added a 0.032 thick x 0.188 dia. unmagnetized disc of Alnico 3 to the bottom of one pole and repeated the field measurement. The disc had virtually no effect on field strength even though past experience has shown that attaching them to the bottom pole surfaces of a fully magnetized strat pickup will significantly alter its tone.

    All the available experimental evidence (and I have accumulated a lot over the past 9 years) indicates that the tonal differences that are observed in samples of the same alloy from different manufacturers are due to variations in ferromagnetic loss. These losses also contribute significantly to observed tonal differences in the soft ferromagnetic materials that are commonly used to make humbucker slugs, screws and keeper bars. In all cases they are sensitive functions of composition, the methods used to cast the materials, and the details of their thermal and mechanical histories. Samples from different foundries vary significantly with respect to one or more of these parameters.

    I don't think it is possible ( or reasonable) to measure the differences in ferromagnetic loss directly but do think it should be possible to describe their effect on pickup tone using reasonably precise terminology. Terms such as 'like a PAF' or 'similar to a '57 strat' get used a lot but have poorly defined meanings.

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    Bent Member Chuck H's Avatar
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    Quote Originally Posted by Mike Sulzer View Post
    Magnets do not have tonal properties; they have magnetic and electrical properties, which contribute to the sound of the pickup in combination with the other components of the pickup. For example they have a magnetic field strength, electrical conductivity, and magnetic permeability.
    I was thinking the same thing. But then I thought, what if that's not all there is. Is it possible that there is some difference in delivery of magnetism as it relates to the bounce back/beating of the string? I ask because I honestly don't know. What I mean is, do some magnetic materials yield/recover more/less in the presence of another magnetic force? This would certainly change the feel and tone. I thought of this because alnico speakers have a reputation for being more compressed sounding when driven hard. I haven't used enough alnico speakers to report on it. Maybe it's bunk, but a lot of guys are spending three times for the alnico speakers what their ceramic counterparts cost for some reason.

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    Quote Originally Posted by Chuck H View Post
    I was thinking the same thing. But then I thought, what if that's not all there is. Is it possible that there is some difference in delivery of magnetism as it relates to the bounce back/beating of the string? I ask because I honestly don't know. What I mean is, do some magnetic materials yield/recover more/less in the presence of another magnetic force? This would certainly change the feel and tone. I thought of this because alnico speakers have a reputation for being more compressed sounding when driven hard. I haven't used enough alnico speakers to report on it. Maybe it's bunk, but a lot of guys are spending three times for the alnico speakers what their ceramic counterparts cost for some reason.
    Here is another view of this issue. Consider the direction of the initial string motion relative to the pole piece locations. In a P bass or J bass pickup the string lies between two pole pieces per string. The mass of the bass strings are high enough to be more damped if the pole piece were too large or strong and located directly below the string. With two smaller pole pieces on each side of the string, any horizontal movement will induce a magnetic pulse in the coil at each end of the horizontal string motion thus emphasizing the second harmonic more than if only a single pole were mounted directly below the string. Emphasizing the second harmonic in a bass makes them sound “less muddy” based on comments about their sound.

    How we perceive sound occurs mostly in the first 30 millivolts seconds of the initial attack, especially when playing live with other instruments.

    Here is a simple experiment to do to hear the result of string movement. Pinch a string between your fingers right above the neck pickup. Pull sideways about .125 inches and release. Listen and/or look at an oscilloscope image of this and look at the relative output of the primary frequency versus the second harmonic at twice the frequency. Now, do this again in the same place over the pickup but this time pinch the string and raise vertically and release. This motion will produce a stronger fundamental output with a more asymmetrical output because on the downward motion of the string it is closer to the magnet while at the upper most string location, it will be in a weaker magnetic field. Try this with the string location located between two magnetic poles and observe and listen to the differences.

    This string motion relative to pole piece locations is a topic that does not get much discussion but based on the comments in this thread, it might be time to discuss this.

    When you add the other typical characteristics of the pickup, such as resonance, Q at resonance, loading by on board controls and effect of coax capacitance on overall performance, you can now see if second harmonic emphasis due to pole placement were in line with resonance characteristics, there could be an emphasized interaction that can now be better understood and added to the discussion.

    Joseph J. Rogowski

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    The mass of the bass strings are high enough to be more damped if the pole piece were too large or strong and located directly below the string.
    String vibration damping requires a loss/transfer of energy. While a strong magnetic field/attraction between string and PU may shift string frequencies for the Y-motion and might increase PU distortion, I don't see a possibility for a damping effect as long as the PU itself doesn't start vibrating.

    Are there any measurements showing PU field induced string damping?

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    Quote Originally Posted by Helmholtz View Post
    String vibration damping requires a loss/transfer of energy. While a strong magnetic field/attraction between string and PU may shift string frequencies for the Y-motion and might increase PU distortion, I don't see a possibility for a damping effect as long as the PU itself doesn't start vibrating.

    Are there any measurements showing PU field induced string damping?
    A fixed magnet next to a vibrating steel string. How can that Not have a damping effect?

    I ask from a "isn't that just common sense?" perspective. I don't have any scientific or engineering background.

    I'll be interested to see how this plays out.

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    Quote Originally Posted by Helmholtz View Post
    String vibration damping requires a loss/transfer of energy. While a strong magnetic field/attraction between string and PU may shift string frequencies for the Y-motion and might increase PU distortion, I don't see a possibility for a damping effect as long as the PU itself doesn't start vibrating.

    Are there any measurements showing PU field induced string damping?
    All vibrating strings are subject to a decay rate governed by these things.
    1. Stiffness at the points of rest being the nut or fret and bridge.
    2. Area of the string exposed to the air causing friction while in motion
    3. The air density around the string.
    4. Any magnetic force near a ferrous metal string.

    A simple experiment is to time the controlled pluck of different strings time of decay using an oscilloscope and timer. The time from initial controlled pluck until the sound level decays into the noise is the variable affected by 1,2, and 3 above. Then add different magnet strengths under the string and measure the decline in decay time from the non magnetized string sample.

    When vibrating strings were moved into a vacuum, it vibrated longer due to only the removal of the air friction but other factors would still apply and cause a vibrating string decay.

    As we tend to want higher output voltages from pickups to improve the signal to noise ratio and improve our subjective perception of the sound, there will always be some damping due to the pickup magnetic field but does this damping affect our musical perception of the tone is the key question. If so, then the magnet in the pickup, or test magnet is too close to the string.

    The creative placement of magnets relative to the position of the string needs to consider all the factors that affect sound quality, good, as well as bad.

    Joseph J. Rogowski

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    Quote Originally Posted by ric View Post
    A fixed magnet next to a vibrating steel string. How can that Not have a damping effect?

    I ask from a "isn't that just common sense?" perspective. I don't have any scientific or engineering background.

    I'll be interested to see how this plays out.
    An immobile fixed magnet cannot produce a damping effect. It just acts like an ideal spring attached that absorbs and releases the same amounts of energy. This follows from the law of conservation of energy. Things change when eddy current effects are involved.
    (I do have a scientific background.)

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    Then add different magnet strengths under the string and measure the decline in decay time from the non magnetized string sample.
    Please show measuring results with perfectly fixed magnets.

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    Quote Originally Posted by Helmholtz View Post
    An immobile fixed magnet cannot produce a damping effect. It just acts like an ideal spring attached that absorbs and releases the same amounts of energy. This follows from the law of conservation of energy. Things change when eddy current effects are involved.
    (I do have a scientific background.)
    Yes, I figured you did.

    Thanks for the explanation in layman's terms. I get it. Ideal spring/ absorbs and releases same amount/ conservation of energy ...I can visualize that.

    A contractor I worked for figured his rafter cuts with calculus on an engineering calculator. I did mine with a measuring tape and framing square. Both methods worked but I remember him saying "Ricky if you know the rules you can play the game"... well there are a lot of things I'll never learn but I do add some things once in a while.

    Thanks again.

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    Quote Originally Posted by Helmholtz View Post
    An immobile fixed magnet cannot produce a damping effect. It just acts like an ideal spring attached that absorbs and releases the same amounts of energy. This follows from the law of conservation of energy. Things change when eddy current effects are involved.
    (I do have a scientific background.)
    Could position of the magnet along the vibrating string length (other than center that is) create a dissonant, and therefor damping vibrations along the strings length? I'm thinking of a problem that is typically called Stratitis. Said to be caused by excessive magnetism due to pickups being adjusted too close to the strings. It causes odd harmonics and damping of sustain is usually reported.

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    "My measurements show the difference in field strength between the two fully magnetized poles to be less than 5% and I find it hard to believe this difference to be large enough to account for the nature and size of the tonal differences between the two materials."

    Maybe 5% is more than enough to cause these changes. Also, if the pickups weren't exactly the same inductance, same capacitance and located in the same pickguard spot, you can not compare them.

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    Quote Originally Posted by Chuck H View Post
    Could position of the magnet along the vibrating string length (other than center that is) create a dissonant, and therefor damping vibrations along the strings length? I'm thinking of a problem that is typically called Stratitis. Said to be caused by excessive magnetism due to pickups being adjusted too close to the strings. It causes odd harmonics and damping of sustain is usually reported.
    Strong magnetic force between string and PU increases the frequencies of fundamental and harmonics for up and down string movement but not for sideways vibration. The result is beating and dissonance, aka. stratitis. Damping can only occur if the PU is loosely mounted and actually vibrates.
    I have not seen any evidence of increased string damping yet.

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    Quote Originally Posted by Helmholtz View Post
    An immobile fixed magnet cannot produce a damping effect. It just acts like an ideal spring attached that absorbs and releases the same amounts of energy. This follows from the law of conservation of energy. Things change when eddy current effects are involved.
    (I do have a scientific background.)
    On the one hand, the ideal spring model makes sense, because there is no damping agent between the magnet and string that serves to eat up the energy, but on the other hand, it's not like a string, either, because the spring will pull when stretched, and push when compressed, but a magnet merely pulls. So the magnetic pull causes the guitar string to be slightly best at all times, when it's moving and even when it's still. A bent string vibrates asymmetrically, because it's being pulled at one end and not the other, and I think it's makes sense that a string which vibrates asymmetrically will sustain for less time than a string that vibrates symmetrically, for the same reason that a spun top will stand and spin around longer if it has perfect symmetry.

    I actually did an experiment with a mechanically plucked D string, listening from a Strat neck pickup, and I moved the pickup from very low, to where the pole piece was almost colliding with the strings, and then I normalized the audio in order to account for the difference in amplitude that accompanies pickup height. Based on that experiment, it does appear that relative amplitude drop more rapidly with increased magnetic interaction.

    Click image for larger version. 

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    Also in this screen shot you can see the harmonic FFT display, here it is expanded

    Click image for larger version. 

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    The most prominent thing that stood out were varying degrees of harmonic beating, especially with the fundamental, and a gradual increase in the 4th and 5th harmonic amplitudes.

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    ..because the spring will pull when stretched, and push when compressed, but a magnet merely pulls.
    Over here we use springs in pull, push and push-pull applications . For pure pull operation some bias force is applied (stretching). This won't change the energy balance.

    I think it's makes sense that a string which vibrates asymmetrically will sustain for less time than a string that vibrates symmetrically, for the same reason that a spun top will stand and spin around longer if it has perfect symmetry.
    Asymmetry influences the vibrational pattern of the string, but I cannot see an influence on the decay of vibrational energy. A spinning top is a completely different problem, it has more degrees of freedom and is not comparable to a vibrating string.

    Based on that experiment, it does appear that relative amplitude drop more rapidly with increased magnetic interaction
    Somewhat hard to tell without further explanation. But if so, the PU must have been vibrating with increasing intensity. The vibration amplitudes will be very low, of course, as the PU has a considerable mass compared to the string.

    The magnetic force between string and PU means an elastical mechanical coupling (just like a spring). A spring can only transfer energy from the source (string) to the load (PU), if the load is at least somewhat movable.
    Decreasing the PU-string distance increases this coupling and thus the probability of PU vibration. A rigidly mounted PU, though, cannot vibrate and suck energy from the strings.

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    It is really easy to observe a plucked strings visual vibrations being damped by moving a hand held magnet near the string and even feel the string vibrations in the fingers holding the magnet due to damping energy transfer from the vibrating string. Eddy currents in various Alnico magnet types will vary and roll off some harsher higher harmonics and add a sound that some people call xxxxxxxxxxxx (fill in your own word(s) here).

    Here is a web link that discusses the Alnico vs Ceramic magnets used in guitar pickups from an engineering perspective. https://www.eng-tips.com/viewthread.cfm?qid=105845

    I hope this puts this issue into a more observable and scientific perspective that pickup builders can use to achieve the desired sound goal.

    Leo Fender had a goal to make guitars that sounded good through his amps with enough output to drive the amp for a good musical sound and limited noise. We are still using a pickup technology that is similar to what was invented a long, long time ago but we now have a scientific vocabulary and test equipment to break it down into more technical details. Our current gap is: how is what we call our subjective and marketing characteristics of a pickup sound backed up by objective science?

    Joseph J. Rogowski

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    It is really easy to observe a plucked strings visual vibrations being damped by moving a hand held magnet near the string and even feel the string vibrations in the fingers holding the magnet due to damping energy transfer from the vibrating string.
    Your experiment confirms my statement regarding string damping via magnetic coupling to a movable load (magnet or PU).
    Please see my post #24.

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    Quote Originally Posted by Tone Cam View Post
    That is clearly the case - just forgot to put it into the list of variables. Several well-known pup makers advertise models with 'degaussed' magnets.

    I think that there are two effects:

    1. The interaction of the poles and strings changes and
    2. The small loop hysteresis losses vary with position on the demagnetization curve.
    Did you receive my reply to your PM?
    I have the impression that the reply function to PMs does not work. Also all of my sent items have disappeared from the box.

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    Quote Originally Posted by Helmholtz View Post
    Over here we use springs in pull, push and push-pull applications . For pure pull operation some bias force is applied (stretching). This won't change the energy balance.
    You say a spring captures and releases energy, but I don't see the magnet capturing or releasing any energy in this context.


    Quote Originally Posted by Helmholtz View Post
    Asymmetry influences the vibrational pattern of the string, but I cannot see an influence on the decay of vibrational energy. A spinning top is a completely different problem, it has more degrees of freedom and is not comparable to a vibrating string.
    When you have asymmetry there will be some beating with the harmonics. The question is, does that resultant beating, or wave interference, decrease the duration of the standing wave? In my own testing, when you have so much string pull that "stratitus" is audible, the sustain is also noticeably reduced at that point.

    Quote Originally Posted by Helmholtz View Post
    Somewhat hard to tell without further explanation. But if so, the PU must have been vibrating with increasing intensity.
    What's this talk about the pickup vibrating? As far as I know, the is pickups is/was perfectly still, unable to move vertically in relation to the strings.

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    You say a spring captures and releases energy, but I don't see the magnet capturing or releasing any energy in this context.
    The potential energy is stored in the magnetic field. A changing distance changes the field and the potential energy. I can't see it either, but this is in the nature of potential energy.

    The question is, does that resultant beating, or wave interference, decrease the duration of the standing wave?
    The answer is "no".

    What's this talk about the pickup vibrating? As far as I know, the is pickups is/was perfectly still, unable to move vertically in relation to the strings.
    I don't think you would notice the tiny vibration of the PU. If there was increasing string damping, the PU must have been vibrating. An immovable PU or magnet can not damp the string.

    If you don't believe me, just ask any physicist you trust.

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