cutting posts?

[Peter Naglitsch]

Straight out of your own posts:

The screw side is slightly stronger in this test.

17% is not a large number, and I do not consider it in disagreement with my crude measurements, and did not mean to imply that they were particularly accurate or final.

First you claimed that the screw side was stronger than the slug side. Then I show you how incorrect that is. At that moment you start to claim that the difference is not significant enough and that it is hardly audible and so on. That is really something.

De facto there is a difference. Is it a big difference or not? As suggested, listen to the pickups you wind. Use your ears and tell us what you think. There is more difference to look for than only output strength. If you do not hear the difference in output and tone/timbre that I hear, I don’t really know if we listen in the same way. But hey, all ears are different.

Is your air core coil (for measuring response) small enough to measure the response near individual pole pieces, or does it look at the overall response?

I’m not sure I get your question completely, but if you mean that the coil is so small I can poke it in the close proximity of one single pole, thus measuring the response from one individual pole and eliminating the response of surrounding poles the answer is no But if you mean that the coil is small enough to be in approximately the same place as the string will be the answer is yes. . And I do not really see the point of measuring the tonal response of individual poles as I am not interested in that but the tonal qualities of the complete pickup

[Robmosis]

Mr. Sulzer I am starting to wonder if you just have a strong personality or if you criticize the way you do to be abnoxious. Of course you could just have an ego the size of this forum.
I found this site to be a fantastic way of getting info and learning the arts I want to. It seems that I have stumbled upon multiple posts in which you seem to purposely get under peoples skin.
Maybe you need take a look at everybody you know and realize how different they all are compared to each other. Now while you realize this, think about the fact that, because they are all so vastly different they will approach tasks in different ways. Meaning people are different and thus they will do things in different ways because this is the easiest way for them to learn or accomplish their task.
So instead of calling people out because their opinion differs from yours why don't you try and just explain your way of doing something. This will get people more apt to look at your opinion and think about it instead of just assuming your an ass and ignoring you.
If I offended you I apologize, but it seems someone needed to tell you.
Sincerely Rob

[chevalij]

I'm still trying to figure out how he converted gauss measurements to db? Especially 1 db which is basically IMPOSSIBLE to notice. How are you measuring your output??

"The two coils in the humbucker I am testing sound about the same. And they measure about the same using a string as a signal source."

[Mike Sulzer]

I'm still trying to figure out how he converted gauss measurements to db? Especially 1 db which is basically IMPOSSIBLE to notice. How are you measuring your output??

The 1 db is based on the change in field strength that Peter measured, not on my measurement.


Sorry, did I get the number of db wrong? The (temporary) magnetization of the string is very close to proportional to the field strength caused by the permanent magnet on the pole piece. Therefore the voltage output of the pickup is proportional to the field strength of the pole.

1 db is indeed pretty small. So if the difference in field strength only causes a db change in output (and maybe that is wrong), then it is small.

[Mike Sulzer]

So instead of calling people out because their opinion differs from yours why don't you try and just explain your way of doing something. This will get people more apt to look at your opinion and think about it instead of just assuming your an ass and ignoring you.
If I offended you I apologize, but it seems someone needed to tell you.
Sincerely Rob

I am not offended, but I do think the importance of opinions in art and engineering is very different.

[Mike Sulzer]

First you claimed that the screw side was stronger than the slug side. Then I show you how incorrect that is. At that moment you start to claim that the difference is not significant enough and that it is hardly audible and so on. That is really something.

You have shown me that the screw side is stronger than the pole side on your pickups. I judge this to be a small difference because it cannot change the level very much. Do you understand my reasoning? The pickup I measured could be different from yours. The difference does depend on the materials in the slugs and screws. I agree that my measurement is not very good; it will improve with better equipment. When you say "That is really something", I think it is because you do not understand what I meant.

De facto there is a difference. Is it a big difference or not? As suggested, listen to the pickups you wind. Use your ears and tell us what you think. There is more difference to look for than only output strength. If you do not hear the difference in output and tone/timbre that I hear, I don’t really know if we listen in the same way. But hey, all ears are different.

I do not hear a big difference between the coils of this pickup. Maybe it is my hearing, which is not as good as it used to be. Or maybe there is not much difference with this pickup.

I’m not sure I get your question completely, but if you mean that the coil is so small I can poke it in the close proximity of one single pole, thus measuring the response from one individual pole and eliminating the response of surrounding poles the answer is no But if you mean that the coil is small enough to be in approximately the same place as the string will be the answer is yes. . And I do not really see the point of measuring the tonal response of individual poles as I am not interested in that but the tonal qualities of the complete pickup

I was thinking that you could measure on the slug side and then the screw side. This would give you another way to measure the differences between the two sides. And this way would depend very little or not at all on the permanent field. The sensitivity of the two sides could be different due to different materials in the two sides. This kind of difference could also result in a different inductance and thus a different resonant frequency; so one could look at it that way as well. These measurements are not perfect because the coils are a bit coupled when sitting on the base. I will measure the full impedance magnitude vs. frequency on these two coils and let you know what I find. It is unlikely that they are all that different because they cancel hum well.

[Peter Naglitsch]

You have shown me that the screw side is stronger than the pole side on your pickups. I judge this to be a small difference because it cannot change the level very much.

Yes, on my pickups. I base the numbers on more than enough pickups to be very confident with those measurements. My pickups have come to a level of consistency were I repeat the same measurements pickup after pickup. How can you “judge” it to be a small difference? You measured one single pickup. Especially a science guy like you must admit that that is a far too small amount of data to draw conclusion from.

I do not hear a big difference between the coils of this pickup. Maybe it is my hearing, which is not as good as it used to be. Or maybe there is not much difference with this pickup.

Or the difference is in the way we listen to pickups. I wind pickups on a regular basis (not as much as some of the guys here) and I constantly listen for the small tiny details in the sound and what difference a small change of factors make. The difference is really in the details. Without a trained ear all pickups of the same basic construction can sound the same. You have to “train” your ear to realise what make a pickup sound good. How do you listen? And how often do you evaluate pickups you have made? And how much pickups have you done? I’m not asking because I think that you need to be an established pickup winder to be allowed an opinion, but it would be interesting to know how much practical and empirical knowledge you have from pickup winding and the details that becomes the sound of the pickup.

I was thinking that you could measure on the slug side and then the screw side. This would give you another way to measure the differences between the two sides.

Yeah I could do that. And I do measure (which I failed to mentioned) the response from one of the individual coils of the pickup if the customer have asked for a coil split pickup. In that case I record the curve of the split coil by itself. But I really think it is interesting to hear you suggest that I should measure both sides of the pickup. Especially as you have earlier argued that there was no significant difference. So why should I bother to measure a difference that you have claimed were of no importance. I’m sorry Mike, but you keep arguing against yourself here.

[Mike Sulzer]

Peter: "How can you “judge” it to be a small difference?"

Here we were discussing the strength of the permanent field. The physics says that when you change the strength of the permanent field, you change the voltage output in proportion. Somewhat over a db is not very much. The physics also says that when you change the permanent field strength, you slide along the hysteresis curve of the material of the cores, possibly changing the permeability. But not my very much in this case.

Peter: "How do you listen? And how often do you evaluate pickups you have made? And how much pickups have you done?"

Put the pickups in a guitar and listen. Always. I have made maybe 30 pickups, nearly all different over the last few years. All experiment, no production. Electric guitars are my hobby. I would like to understand how much of the differences can be attributed to changes in the electrical circuit affecting the frequency response (measurable in principle), and how much must be attributed to the details of small effects of the magnetic materials (harder to quantify). What I am doing is not all like trying to make a pickup with a particular sound because your customer wants it. I want to understand how it works, and so the relationship between measurement and sound is important.

Peter:"I’m sorry Mike, but you keep arguing against yourself here."

Actually, no. We started out discussing the effects of the differences of the permanent field on the screw and core side, at least as I understood it. The discussion has broadened a bit and seems to cover anything one can hear, which brings up the effects of the magnetic materials in the two sides on the sensitivity of the pickup at different frequencies. A much more complicated topic. Small differences can be more important when you consider what the pickup does to the signal (inductance, capacitance, resistance, eddy currents, etc.) rather than just how strong the permanent field is.

[Peter Naglitsch]

Peter:"I’m sorry Mike, but you keep arguing against yourself here."

Actually, no.

Well, actually you do. First you argue about the tiny difference that wasn’t audible, only a dB (were the hell did you get a single dB from. You claim it to be one dB and then it suddenly is the truth. Back that up with science my friend) and nothing worth writing home about. Then you want me to measure the output and response from the individual coils. If there were no difference, why should I measure the non existing difference? That is, in my book, arguing against yourself.

I’m sorry Mike. You are probably a swell guy. You’re probably also a great radar engineer. But you have one single flaw. You haven’t noticed that you have one mouth and two ears. Consider that a hint to listen twice as much as you talks. You argue and argue and refuse to take in what other people with far more experience tell you. That gets extremely boring after a wile and I guess that’s why you (as a fellow forum member pointed out to me in a PM) got banned from the MIMF forum. I don’t have the time nor interest in discussing with someone that doesn’t take in what other with greater experience can inform them about because they are too busy to convince the world about their own ideas and thus disregards everything that contradict their own original opinion.

I’m out of this discussion. Live well Mike

[Mike Sulzer]

I got my Hall effect chips (A1322LUA from Allegro MicroSystems, $25 plus shipping from their online store for a calibrated chip). You drive it with a regulated 5V supply and connect it to a DVM. This pickup (Japanese humbucker from Allparts several years ago) does indeed have stronger field on the screw side. The average of the six is 14% stronger on the screw side. This different from the humbuckers that David and Peter have measured.

Since it still is not clear, I will try again. Peter measures 17% stronger field on the slug side. By Faraday's law of induction, this will be 17% more voltage from the slug coil. This is about 1.36 db. This is a small difference in output level.

My humbuckder measures 14% more field on the screw side. It uses different magnetic materials and/or has a somewhat different geometry. The two sides of this pickup are slightly better matched in output level than the average of what Peter measures.

I will discuss a difference between the ac response of the two coils in a later post.

[Joe Gwinn]

Peter measures 17% stronger field on the slug side. By Faraday's law of induction, this will be 17% more voltage from the slug coil. This is about 1.36 db. This is a small difference in output level.

When computing output voltage, it's the change in total (integrated) flux through the core (and thus coil) that matters, not the peak flux density as measured by a gaussmeter) that matters.

Because the poles are not saturated (due to the big air gap), the same total flux going through a smaller pole will have higher flux per unit area (and thus gauss readings), but will not generate more voltage. If leakage is reasonably symmetric and coils are identical, the same voltage will be generated.

[Mike Sulzer]

When computing output voltage, it's the change in total (integrated) flux through the core (and thus coil) that matters, not the peak flux density as measured by a gaussmeter) that matters.

The total flux through the core from the vibrating string is proportional to the field of vibrating string. That field is proportional to the magnetization of the string, which is (almost) proportional to the permanent field at the string (for small changes in the field). Increase the permanent field by 17%, and you increase the induced voltage by approximately 17%. (This is not quite exact because when you increase the permanent field in the core, you move along its hysteresis curve a bit, thus affecting its ability to amplify the varying field from the string. But you are not moving very much.)

Because the poles are not saturated (due to the big air gap), the same total flux going through a smaller pole will have higher flux per unit area (and thus gauss readings), but will not generate more voltage. If leakage is reasonably symmetric and coils are identical, the same voltage will be generated.

So you are saying that as one makes the core thinner, the measured field goes up (everything else equal)? This cannot be true. Consider the limiting case: as the core gets very thin, it must have no effect. You get a much reduced field. The reason it is wrong is because the flux through the two sides is not the same. The high permeability material lines up with the applied field thus increasing the flux. No material, no increase. In the case of the humbucker, we must consider how the screws and slugs are coupled to the magnet, the amount of magnetic material in each, and the fact that a screw has a head. The relative strength can go either way, as Peter's, David's, and my measurements indicate.

[Joe Gwinn]

The total flux through the core from the vibrating string is proportional to the field of vibrating string. That field is proportional to the magnetization of the string, which is (almost) proportional to the permanent field at the string (for small changes in the field). Increase the permanent field by 17%, and you increase the induced voltage by approximately 17%. (This is not quite exact because when you increase the permanent field in the core, you move along its hysteresis curve a bit, thus affecting its ability to amplify the varying field from the string. But you are not moving very much.)

This still confuses magnetic flux (unit is the Weber) and magnetic flux density (unit is the Tesla). (One Tesla equals 10,000 Gauss.)

It's the flux in Webers that must rise by 17% to yield a 17% increase in voltage induced by a given string motion.

An optical analogy would be a light fixture consisting of a frosted lightbulb backed by a white reflector. If I measure only the optical brightness of the surface of the lightbulb, can I figure out how bright the surface of my desk will be? No. Insufficient information. I need to know the brightness versus location curve for the lightbulb and the reflector for a start, so I can integrate brightness over the area of bulb and reflector.

So you are saying that as one makes the core thinner, the measured field goes up (everything else equal)? This cannot be true.

I am saying that as the core gets thinner (the cross sectional area of the core becomes smaller) the flux density in Tesla increases, for a given total flux in Webers. Nor can it be otherwise, as total flux in Webers is the integral of flux density in Teslas over the cross section of the core in question.

Given that the permeability of steel is about 1,000 times that of air, essentially all the flux will travel in a steel core if it can. The smaller the cross sectional area, the higher the flux density (Gauss or Tesla) in the core, at least until the steel becomes saturated. Saturation is not an issue in pickups.

http://en.wikipedia.org/wiki/Electromagnetism

Consider the limiting case: as the core gets very thin, it must have no effect. You get a much reduced field.

No. Covered above.

The reason it is wrong is because the flux through the two sides is not the same. The high permeability material lines up with the applied field thus increasing the flux. No material, no increase. In the case of the humbucker, we must consider how the screws and slugs are coupled to the magnet, the amount of magnetic material in each, and the fact that a screw has a head.

The total amount of flux available is what the magnet generates. This flux will flow by the easiest path, and steel has 1000 times the permeability of non-ferromagnetic materials. So, if we have a humbucker magnetic circuit consisting of a row of steel slugs, a bar magnet, and a row of filister-headed screw poles, the same total flux will go through the slugs as through the screw poles. If the screws are smaller than the slugs, the peak flux density in Tesla (or Gauss) over the screw poles will be greater than the peak flux density over the slug poles.

There will be slight differences in leakage flux because the magnetic resistance of the screws (especially the threaded parts) is higher than that of the slugs, both because the cross-section is smaller and because the screw material has different permeability than the slug material.

I recall the SK's FEMM results showed these effects pretty clearly.

The relative strength can go either way, as Peter's, David's, and my measurements indicate.

It would take far better controlled experiments to be able to make such comparisons. A better test would be slugs of various diameters that were machined from the same piece of mild steel, so the material is guaranteed to be the same.

[Mike Sulzer]

Given that the permeability of steel is about 1,000 times that of air, essentially all the flux will travel in a steel core if it can.

Let's take this as a starting point. My interpretation of that statement is that the B field inside a slug should not decrease significantly as one looks inside the slug at greater distances from where it connects to the magnet. This plot:http://www.naic.edu/~sulzer/magWithRod1.png is the output from FEMM of a cylindrical magnet with a piece of steel (slug) attached. (The plot shows the right half only.) The field decreases a lot from the magnet to the other end of the slug. I think this means that the flux is not well confined, and this is what I expect from open rather than closed magnetic circuits. How do you interpret this?

[Mike Sulzer]

Some measurements that show how the field falls off as the length of a 3/16" dia. steel rod is increased (magnet is Neo disk, 3/16 by 1/16, measurement on end opposite where magnet is located):

rod l. Gauss
1/4" 379
3/8" 280
1/2" 227