Magnet type vs sound

[Marko Ursin]

Just a very simplified questiob;
Let’s say I have a pickup with steel blade. I also have a ceramic, A5 and neodymium magnet that all are the same strength and when mounted on the pickup read the same Gauss at blade top. How much do the sound differ with each magnet?
I understand that if the magnets are same size they will have effect on sound via different strength.

[mozz]

Your pickup inductance will change, hence a change in sound.

[Antigua]

I also have a ceramic, A5 and neodymium magnet that all are the same strength and when mounted on the pickup read the same Gauss at blade top.

Why would they all measure the same strength, though?

[eschertron]

Why would they all measure the same strength, though?

I think the OP's question is hypothetical?

But yours is a fair question. I know nothing about magnets, but for settling hypothetical versus realistic can we say:
1. Is it possible/likely to find A2 and A5 magnets that produce the same field strength. Do they sound the same? How do they differ?
2. Is it possible to find A5 and ceramic magnets that produce the same field strength? same questions
3. Is if possible to find ceramic and neo magnets, etc. etc...

Null hypothesis: If the field strength is the same, they sound the same. Please tell me why this is false.

[Antigua]

I think the OP's question is hypothetical?

But yours is a fair question. I know nothing about magnets, but for settling hypothetical versus realistic can we say:
1. Is it possible/likely to find A2 and A5 magnets that produce the same field strength. Do they sound the same? How do they differ?
2. Is it possible to find A5 and ceramic magnets that produce the same field strength? same questions
3. Is if possible to find ceramic and neo magnets, etc. etc...

Null hypothesis: If the field strength is the same, they sound the same. Please tell me why this is false.

If a material is conductive, it will cause eddy currents, bringing down the treble response of the pickup to some extent (by way of reducing the Q factor). If the material is permeable, it will boost the magnetic field created by the coil(s), increasing the inductance, also bringing the resonant peak down somewhat. Ceramic and neodymium are effectively inert, having low permeability and conductivity. It's almost the same as if air occupied their space. AlNiCo has a non-trivial amount of permeability and conductivity, AlNiCo 2/3/4 more so than AlNiCo 5, so they cause some eddy current and increase the inductance, reducing the treble response relative to ceramic or neodymium.

The degree to which the treble is reduced not only owes to the permeability and conductivity of the material, but also much of it there is, and the degree to which it intersects with the magnetic field of the coil(s). Materials in or near the core of the coils have a much greater impact than metals that are farther from the coils. Steel has a much higher conductivity and permeability than AlNiCo, and because a lot of pickups feature steel slugs and screws in the cores of their coils (P-90, PAFs, Filter'trons), those steel parts the primary cause of their high inductance and eddy current induced treble attenuation, not the magnets. The only context in which AlNiCo is significant in that role is in Fender style pickups, where AlNiCo is used as pole pieces, and occupy the core of the pickup's coil. In pickups where the magnet is external to the core of the coil, it has a much smaller effect in terms of inductance and eddy currents.

[eschertron]

If a material is conductive, it will cause eddy currents, bringing down the treble response of the pickup to some extent (by way of reducing the Q factor). If the material is permeable, it will boost the magnetic field created by the coil(s), increasing the inductance, also bringing the resonant peak down somewhat. Ceramic and neodymium are effectively inert, having low permeability and conductivity. It's almost the same as if air occupied their space. AlNiCo has a non-trivial amount of permeability and conductivity, AlNiCo 2/3/4 more so than AlNiCo 5, so they cause some eddy current and increase the inductance, reducing the treble response relative to ceramic or neodymium.

The degree to which the treble is reduced not only owes to the permeability and conductivity of the material, but also much of it there is, and the degree to which it intersects with the magnetic field of the coil(s). Materials in or near the core of the coils have a much greater impact than metals that are farther from the coils. Steel has a much higher conductivity and permeability than AlNiCo, and because a lot of pickups feature steel slugs and screws in the cores of their coils (P-90, PAFs, Filter'trons), those steel parts the primary cause of their high inductance and eddy current induced treble attenuation, not the magnets. The only context in which AlNiCo is significant in that role is in Fender style pickups, where AlNiCo is used as pole pieces, and occupy the core of the pickup's coil. In pickups where the magnet is external to the core of the coil, it has a much smaller effect in terms of inductance and eddy currents.

So for an experiment with two Fender-type coils, one with A2 and one with A5: If we are given that the pole pieces are the same size, have uniform construction, are positioned in the coils the same way, and are charged the same (I assume that field strength correlates strongly with magnet charge?) then the differences in permeability and conductivity (the only variables under consideration) result in an A2 coil that damps HF response and pulls the resonant frequency down more than the A5 coil. In the vernacular, A2 is 'darker' and A5 is 'brighter'. Can this be said?

I realize all this ignores the history of pickup making, with all its variation on coil winding and magnet charging. But for an ignoramus like me, seeing a result in isolation helps paint the picture

[Antigua]

So for an experiment with two Fender-type coils, one with A2 and one with A5: If we are given that the pole pieces are the same size, have uniform construction, are positioned in the coils the same way, and are charged the same (I assume that field strength correlates strongly with magnet charge?) then the differences in permeability and conductivity (the only variables under consideration) result in an A2 coil that damps HF response and pulls the resonant frequency down more than the A5 coil. In the vernacular, A2 is 'darker' and A5 is 'brighter'. Can this be said?

This is correct. I once ordered AlNiCo 2, 3, 4 and 5 pole pieces, and then stuck them each into a plastic Strat-style bobbin, and produced bode plots with each of the AlNiCo sets, including air coil:



You can see how AlNiCo 2, 3 and 4 produce the lowest frequency, due to having the highest permeability, and the lowest Q factor, due to having the highest conductivity. The AlNiCo 3 appears to be more conductive than the AlNiCo 4, which appears to be more conductive than the AlNiCo 2, but all appear to have effectively identical permeability. AlNiCo 5 has both lower conductivity and permeability, so it trends closer to the "air coil".

[eschertron]

This is correct. I once ordered AlNiCo 2, 3, 4 and 5 pole pieces, and then stuck them each into a plastic Strat-style bobbin, and produced bode plots with each of the AlNiCo sets, including air coil:

[ATTACH=CONFIG]56740[/ATTACH]

You can see how AlNiCo 2, 3 and 4 produce the lowest frequency, due to having the highest permeability, and the lowest Q factor, due to having the highest conductivity. The AlNiCo 3 appears to be more conductive than the AlNiCo 4, which appears to be more conductive than the AlNiCo 2, but all appear to have effectively identical permeability. AlNiCo 5 has both lower conductivity and permeability, so it trends closer to the "air coil".

This was done with unmagnetized pole pieces, demonstrating how the AlNiCo interacts with a field produced by the coil? I can see that A5 is different than the others, but I'm not certain that if I could even hear the difference I'd be able to qualify it. Not to derail the thread, but does A5's appeal come from other aspects of its composition, like how much charge it can hold relative to A2 and the others?

[Antigua]

This was done with unmagnetized pole pieces, demonstrating how the AlNiCo interacts with a field produced by the coil? I can see that A5 is different than the others, but I'm not certain that if I could even hear the difference I'd be able to qualify it.

The permeability and the conductivity of the AlNiCo are in play regardless of whether the pole pieces are charged or not. I believe that in order for the permeability of the AlNiCo to drop, it would have to be saturated within a powerful magnetic field, one that's a lot stronger then it's own residual flux.

The inductance measured 1.9 henries with AlNiCo 5, and increased to 2.2 henries with AlNiCo 2/3/4. It's a small difference, but you would likely be able to perceive the drop in resonant peak. In a PAF type humbucker context, the increase in inductance is much smaller, only about 20 millihenries or so, since the AlNiCo car is not on the core of the coil(s). There's no way you'd be able to perceive an increase or drop of 20mH, especially with a pickup that features a very low Q factor, due to the steel slugs and screws.

Not to derail the thread, but does A5's appeal come from other aspects of its composition, like how much charge it can hold relative to A2 and the others?

I think if you're going to consider when makes A2 or A5 sound more to your liking, at that point it makes sense to think about how magnetic strength itself affects things, and not only consider the electrical affects of the metals. When you subject one side of the guitar strings to magnetic pull, it leads to asymmetrical stiffness along the length of the string, and that affects the harmonic amplitudes in ways that defy simple description. It's similar to how pinch harmonics shift harmonic amplitudes, except that the "pinch" is a soft, broad magnetic pull, rather than a fingertip.

[Chuck H]

Sooooo... What could be wrong with experimenting with something like a neo cap on an iron core!?! There's probably more than one way to skin any cat. The subtleties would probably make experimentation prohibitive from a manufacturers standpoint, but I bet you could effectively simulate any magnet type with neo if you only used it as a cap on some other material of considered permeability. So the neo provides the magnetism to the string and the rod provides the permeability for the desired inductance. It may seem complicated at first, but it could open up a world of possibilities. So you have neo caps of relative magnetic strengths and rods of relative permeability. Mix and match. Which combination sounds right for duplicating "alnico5", "alnico2", ceramic, etc.

Food for thought?

[HaroldBrooks]

The permeability and the conductivity of the AlNiCo are in play regardless of whether the pole pieces are charged or not. I believe that in order for the permeability of the AlNiCo to drop, it would have to be saturated within a powerful magnetic field, one that's a lot stronger then it's own residual flux.

The inductance measured 1.9 henries with AlNiCo 5, and increased to 2.2 henries with AlNiCo 2/3/4. It's a small difference, but you would likely be able to perceive the drop in resonant peak. In a PAF type humbucker context, the increase in inductance is much smaller, only about 20 millihenries or so, since the AlNiCo car is not on the core of the coil(s). There's no way you'd be able to perceive an increase or drop of 20mH, especially with a pickup that features a very low Q factor, due to the steel slugs and screws.



I think if you're going to consider when makes A2 or A5 sound more to your liking, at that point it makes sense to think about how magnetic strength itself affects things, and not only consider the electrical affects of the metals. When you subject one side of the guitar strings to magnetic pull, it leads to asymmetrical stiffness along the length of the string, and that affects the harmonic amplitudes in ways that defy simple description. It's similar to how pinch harmonics shift harmonic amplitudes, except that the "pinch" is a soft, broad magnetic pull, rather than a fingertip.

Thanks for the education. I came into understanding about pickups very late in my tenure as a guitarist. They can make a world of difference in performance of playing, not just frequency response alone, but I belive with dynamics and transit response, particularly when matched with the correct amp. I've been using an EQ at the end of my rig for years, but to be honest it's a cheaters way of trying to replicate some different types of pickups, and falls short considerably. An EQ is great for making sweeping changes, but can't replicate what's going on with a pickup. Kinda like the problem with modeling a guitar amp correctly by taking just a software perspective. There is a physicality to guitar amps and pickups that is part of their environment, and if you seperate or ignore that, you get a cardboard cutout for your efforts.

I particularly liked that you mentioned the pickups pull on the strings. Important from what I've seen and done. Also adjusting pole pieces on pickups that allow it.

I am very interested in Eddy currents as they relate to magnets and temporary states of demagnitization that happen with speaker magnets, and perhaps pickups as well. I believe I can hear the differences between Field coil speakers and there very similar PM counterparts. If you look at some of the speakers in history at the point of transistion to Alnico, they use the same cone, basket, voice coil. All that has been changed is the magnet and perhaps the pole piece to accomdate the perma magnet, but that seems to be enough to change the speaker sound noticeably.

One day I would like to explore that in a experiment. I've seen some the high end German stereo speakers still use Electro Magnets, and if the power supply is stable and sufficient, I believe that arrangement is more stable than a Perma Magnet, and perhaps better for Hi-Fi, but worse for guitar amps ? Who knows until you try.

It's complex as what is better for Hi-Fi may be worse for a guitar amp. Most field coil speaker old guitar amps have unstable voltage supplies, but there may lie the charm.

Sorry to hijack the thread with speaker talk, but I felt it's related as they use or have used the same magnets.

Will stop now.

[jop120]

You can go down the science route to figure out why they all sound different, but if you wanna make good sounding pickups then IMHO it's not really of much relevance. Each type of magnet sounds very different and some work in certain situations and some don't.
Make a bunch of pickups with different wind styles, gauges of wire, insulation type, number of turns etc. Then get a load of different magnets and try them all out, then listen to them all and try to remember how they sound. After a while it'll just become instinctive and you'll know what to expect from a pickup before you've even made it.

[Mike Sulzer]

As you wrote: "Each type of magnet sounds very different and some work in certain situations and some don't." If you understand how the electrical properties of the different magnets affect the electrical circuit of the pickup, then you have a good idea what those situations are. Anyway, you can pick a magnetic material and use it in a way such that it has no significant effect on the electrical properties of the circuit. Then you design the properties of the circuit in more appropriate ways. But you will never get there if all you do is try different combinations of various things.

You can go down the science route to figure out why they all sound different, but if you wanna make good sounding pickups then IMHO it's not really of much relevance. Each type of magnet sounds very different and some work in certain situations and some don't.
Make a bunch of pickups with different wind styles, gauges of wire, insulation type, number of turns etc. Then get a load of different magnets and try them all out, then listen to them all and try to remember how they sound. After a while it'll just become instinctive and you'll know what to expect from a pickup before you've even made it.

[jop120]

I dunno, my goal is to make awesome sounding pickups and I find there aint no better way of measuring if something sounds good than with the old ears. Also this is the world of the guitar not the Hifi, what is correct is often wrong, what sounds good sounds good, it's really that simple. I've had a lot of success by trying stuff out and having a good listen.

[Mike Sulzer]

I did not write that measuring the electrical properties of pickups is to determine if they sound good or not. Not true at all. The purpose is to better understand what affects the sound of a pickup and how to use available materials to make improvements. That is what I wrote in my post from 1:13 today, not at all like what you seem to be saying I wrote.

I dunno, my goal is to make awesome sounding pickups and I find there aint no better way of measuring if something sounds good than with the old ears. Also this is the world of the guitar not the Hifi, what is correct is often wrong, what sounds good sounds good, it's really that simple. I've had a lot of success by trying stuff out and having a good listen.