How do the metals in Alnico affect tone?

[kevinT]

I know that each grade of alnico has a different effect on tone. However, what i am unclear about is how do the metals in the bar magnet affect the current that is induced in the coil making a pickup sound the way that it does.

another way to put it....A magnetic field is a magnetic field whether it is A2 or A8 magnetic field ...right? (I'm not considering gauss here) How do the percentages of metal alloys of an A2 and the alloys of an A8 translate into the tone.

For me there is a disconnect in how the metal in the mags physically flavor/alter the tone.

Does it flavor the current in the coil a certain way.

Can anyone explain this in layperson's terms?

[David King]

I heard a talk with the head pickup designer from Guild in 1988 and he swore up and down that the way the current is induced in a pickup is the subtle demagnetization and re-magnetization of the magnet by the string passing back and forth over it. He claimed that this is why Alnicos were better than ceramics, they had a lower coercive threshold and were more easily affected by the string. I have nothing to back this theory up but it's a theory we could probably test out. It certainly doesn't explain why samarium -cobalt and neodymium powered pickup work as well as they do. (when I asked him about the feasibility of using rare earth magnets in pickups he said they wouldn't work well but I doubt he'd even tried them at that point.)

[black_labb]

aside from the gauss, i would say it is inductance. inductance changes the frequency response in the coil. when different materials are put in the middle of a coil the inductance changes. i think more inductance will create a bit of a high end roll off, but could be more complicated than that.

in very simple terms, inductance is a coils resistance to change (ie ac). inductors are used to smooth out voltage ripple in amplifiers to clean up the dc.

someone with more knowledge will probably chime in.

the resistance of the alnico grade may effect it as well (eddy currecnts maybe?)

[soundmasterg]

I will say that my RIC humbuckers that use samarium cobalt magnets have a bright top end with lots of power, and the highs can be somewhat harsh. I use flatwound strings on this guitar to tame the highs down a bit.

Greg

[David Schwab]

I heard a talk with the head pickup designer from Guild in 1988 and he swore up and down that the way the current is induced in a pickup is the subtle demagnetization and re-magnetization of the magnet by the string passing back and forth over it. He claimed that this is why Alnicos were better than ceramics, they had a lower coercive threshold and were more easily affected by the string. I have nothing to back this theory up but it's a theory we could probably test out. It certainly doesn't explain why samarium -cobalt and neodymium powered pickup work as well as they do. (when I asked him about the feasibility of using rare earth magnets in pickups he said they wouldn't work well but I doubt he'd even tried them at that point.)

Current is induced by what is called "variable reluctance".

The idea is when ever a magnetic field is moved by a conductor, current flows. And conversely when you flow current down a wire, it produces a magnetic field, as long as the wire has resistance. Electric fields and magnetic fields are considered two parts of the same phenomenon.

I think some magnets have a "softer" field, and that changes the tone.

[chevalij]

I'm with KevinT. I dont' get it. To me, the only thing that makes sense it the gauss of the magnet. Stronger field, stronger signal. How the hell can the amount of cobalt affect tone. It's magic I tell ya. Abigal was a witch, or a duck, I can't remember which one but she floated!

[Mike Sulzer]

David and Black_labb mention two aspects of the same thing: most ferromagnetic materials respond to applied magnetic fields and amplify them. The degree to which they do this is called the permeability. So the pickup cores do in general amplify the small fluctuating field from the vibrating string. And the core amplifies the field from currents flowing in the coil, increasing the inductance.

But rare earth magnets do not do this significantly; their fields are mostly frozen in, which means they have low permeability. But when used as pickup cores, their very powerful fields magnetize the strings strongly and so they can give high output even though the permeability is low. The high field can make a guitar string sound harsh since its vibration is affected. Heavy strings with high tension should be less affected, but David would know more about that.

[David King]

Hey Mike! What the hell is a nice person like you doing in a place like this? Welcome.

So to summarize, "hard" (low permeability) mags like Ndym and SmCo and C8 are good for bass but not so good for guitar while "soft" (high permeability) magnets like A2 and A3 are better for high strings to the average human ear?

[Possum]

how magnets "sound" is not just gauss. You can have an alnico 4 magnet and an alnico 2 magnet hitting exact same charges and they are not going to sound the same. Inductance for sure is a prime thing that affects tone but I don't think you're going to find a critical analytical list of how each element is going to affect tone. Some elements affect coerciviity and permeability so the more of that stuff in there its going to change how the sound signal sounds. The amount of iron is key also as this is related to inductance. I'm starting to learn more about this stuff because I'm trying to figure out magnetic alloys that are out there. Same stuff as used in magnets. Really, all you can do is use each alloy and listen what it does to bass, midrange, and treble and dynamics. I suppose you could try to quantify that somehow but some thing can't be quantified I guess.....

[Mike Sulzer]

Hey Mike! What the hell is a nice person like you doing in a place like this? Welcome.

So to summarize, "hard" (low permeability) mags like Ndym and SmCo and C8 are good for bass but not so good for guitar while "soft" (high permeability) magnets like A2 and A3 are better for high strings to the average human ear?

Hi David; I have lurked around here for a few months, but took some time off from posting anywhere after I got booted off mimf. (Hello to David Schwab, too!)

Yes, I agree. If you are using just the magnets and want reasonably high output, you have be careful of excessive string pull with neo and SMCO with guitar strings. On the other hand, if you do not need such high output, you can avoid the string pull by using smaller magnets, or moving them down in the coil. I think the rare earth magnets are most convenient when you are using cores made from some non-permanent magnetic material. They allow you to adjust the inductance (and thus the resonant frequency) independently of the magnetic field strength. The rare earth mags do not affect the inductance, so you can optimize the field strength by adjusting the size of the magnets on the bottoms of the pole pieces (or on top if you use really small magnets) without changing the resonant frequency.

On the other hand, I really like pickups with alnico pole pieces. Some time I want to make a pickup like described above, with both the field strength and resonant frequency exactly matching, for example, a tele lead pickup and then compare them.

[David Schwab]

But rare earth magnets do not do this significantly; their fields are mostly frozen in, which means they have low permeability. But when used as pickup cores, their very powerful fields magnetize the strings strongly and so they can give high output even though the permeability is low. The high field can make a guitar string sound harsh since its vibration is affected. Heavy strings with high tension should be less affected, but David would know more about that.

Hi Mike!

I haven't tried them with guitar yet, but I use steel cores in my coils most of the time anyway.

I was able to try a few pickups out swapping between ceramic 8, alnico V and N42 neodymium magnets. It was interesting hearing the tonal changes with each magnet. Using the ceramic as a baseline, alnico is darker and spongier, while the neo has more texture in the mids and highs... a sort of snarly tone.

[SK66]

I believe the two main factors are Gauss and Permeability.
Both are determined by the magnet's material composition and method of creation. Gauss is gauss and has it's effect which I think has been fairly well explained.
However, as Possum noted, two magnets with the same gauss may have different tonal characteristics.
Think of a higher permeability magnet as a "more efficient" magnet. Because it is more efficient at transmitting its magnetic field, it is also more efficient in "recirculating" it's magnetic field to the opposite pole. The resulting magnetic field will have a narrower aperature making it more "focused/brighter" sounding.

[David Schwab]

That fits right into what I hear with the various magnets I've tried.

[Possum]

Are there specs or charts that show this? The same thing applies to magnetic alloys and metals, I haven't seen anything on this comparing alnico grades, that would be something to see if it exists somewhere.....

[David King]

http://www.grouparnold.com/products/alnico/alnico_cast_properties_2-3-4.htm
http://www.grouparnold.com/products/alnico/alnico_cast_properties_5-800.htm
http://www.grouparnold.com/products/alnico/alnico_cast_properties_8-9.htm
http://www.magnetapplications.com/USA/alnico.htm

[Possum]

ok, now explain all those terms to me in detail :-)
Where the hell do you learn this stuff anyway? Physics books? Porn sites?

[Mike Sulzer]

ok, now explain all those terms to me in detail :-)
Where the hell do you learn this stuff anyway? Physics books? Porn sites?

You need to understand some kind of combination of physics and engineering. Most of those terms are shorthand ways of expressing what happens in a materials hysteresis curve. Wikipedia has a pretty good explanation: http://en.wikipedia.org/wiki/Hysteresis. Scroll down to Magnetic hysteresis. Remember that you apply a magnetic field (H) on the horizontal axis, and see the result (B) on the vertical axis.

[dazzlindino]

Isnt any pickup or change to a pickup, just a way to make electrons move?
There is no "sound" coming out of a pickup, just different intensities of electron movement, correct or not?

[David Schwab]

Isnt any pickup or change to a pickup, just a way to make electrons move?
There is no "sound" coming out of a pickup, just different intensities of electron movement, correct or not?

No, it's way more complex than that. A coil of wire is also an inductor, plus there's resistance to the coil, and capacitance. And the coil has a resonant frequency, and is anything but flat.

Then you have different types of cores which each change the response curve.

And different magnets sound different.

The only time you get an almost pure signal is from a very low impedance coil, which is why they make microphones that way. And even then, you have response curves.

I can wind identical pickups, just changing things like wire gauge and amount of turns, and get drastically different sounding pickups.

Think of it this way, does a Strat pickup sound like a Jazzmaster pickup, or a P-90, or even a Tele for that matter?

Pickups do have their own sound. I started off making pickups with no tone of their own, but now I'm having fun making pickups with various tonalities.
:D

[dazzlindino]

My point is that the electron pulse/push etc. is all that a pickup does,
and changing magnets, poles, windings, gauge all influence this.
Now givin that it makes pedals / amps respond differently , attenuating frequencies and so forth, is what makes it sound different.
Absolutley no part in itself makes a sound unless it is coupled to an amp that has been graciously set up to mimic what we think a guitar should sound like.
On amps changing tubes, biasing, different resisters , caps etc are all changing the flow of electrons, which at the end of the line move speakers, which would not make a sound in a vacume , no?
In other words we are jetting a carburator, put the right jets in and the motor is in better "tune" / sounds better.
I am not here to argue but to learn from Jedi masters:D
Thanks, and God Bless

[David Schwab]

Well it all starts at the guitar. But even if you put a pickup on a guitar, with strings and all, and you don't plug it into anything, it's not making any sound. ;)

But the reason why it's not simply pushing electrons (which is not how current flows anyway) it's an imperfect device, and that's where the tone comes from.

It's also moving around photons by the way. :eek:

[dazzlindino]

So its not moving electrons, but it is moving photons....

But something is moving, how dynamically this accurs is dependant upon all parts that comprise a pickup? A stronger magnet would make a stronger pulse, more windings would mean more resistance to said pulse, but once moving would in effect hit the amp harder...

hehe he said harder....
shut up Beavis....:o

[Mike Sulzer]

So its not moving electrons, but it is moving photons....

But something is moving, how dynamically this accurs is dependant upon all parts that comprise a pickup? A stronger magnet would make a stronger pulse, more windings would mean more resistance to said pulse, but once moving would in effect hit the amp harder...

hehe he said harder....
shut up Beavis....:o

Suppose you throw a switch connecting a battery to two wires that then connect to a resistor. Current starts flowing and moves down the wire at almost the speed of light. Electrons do move, but not very fast. The current flows by electrons bumping other electrons along. There has to be a net motion of electrons for this to happen, but they move much more slowly (fraction of inch per second) than the signal produced by the bumping (almost at the speed of light). Photons have nothing to do with this. The flow of electric current is explained here: http://en.wikipedia.org/wiki/Electric_current

[David Schwab]

So its not moving electrons, but it is moving photons....

It was a bit tongue in cheek, but my point was that the electromagnetic force operates via the exchange of messenger particles-- photons and virtual photons.

What is a magnetic field? (http://www.geocities.com/dsligar.geo/mfield.html)

Richard Feynman refers to photons from a magnet in his book, Q.E.D., The Strange Theory of Light and Matter. Feynman explains that under certain circumstances, including when a very large number of electrons are all moving in the same way, such as going around in the coils of an electromagnet, a large number of photons are emitted, all of exactly the same kind.

The energy in a magnetic field is carried by photons. Photons make your magnet stick to the fridge. Photons have no charge, but they exert momentum, and that momentum causes attraction and repulsion.

Photons are also thought to carry the charge up a wire at the speed of light that gets the electrons wiggling.

And yes, photons are responsible for visible light, and also radio and microwaves. The frequency is what changes. They have more energy at lower frequencies, such as in magnets.

Also see Wikipedia: Photon (http://en.wikipedia.org/wiki/Photon)

In physics, the photon is the elementary particle responsible for electromagnetic phenomena. It is the carrier of electromagnetic radiation of all wavelengths, including gamma rays, X-rays, ultraviolet light, visible light, infrared light, microwaves, and radio waves.

And also Electromagnetic Radiation (http://en.wikipedia.org/wiki/Electromagnetic_radiation)

Electromagnetic (EM) radiation, is a self-propagating wave disturbance in space which is the phenomenon perceived by the human eye as light. EM radiation has an electric and magnetic field component which oscillate in phase perpendicular to each other and to the direction of energy propagation. Electromagnetic radiation is classified into types according to the frequency of the wave, these types include (in order of increasing frequency): radio waves, microwaves, terahertz radiation, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays. Where radio waves have the longest wavelength and Gamma rays have the shortest EM radiation carries energy and momentum, which may be imparted when it interacts with matter.

Particle model
Because energy of an EM wave is quantized, in the particle model of EM radiation, a wave consists of discrete packets of energy, or quanta, called photons. The frequency of the wave is proportional to the magnitude of the particle's energy. Moreover, because photons are emitted and absorbed by charged particles, they act as transporters of energy.

In the everyday world it doesn't really matter. :D

[Mike Sulzer]

In the everyday world it doesn't really matter. :D

Exactly; when explaining something to someone, it is a good idea to use the concepts that apply. For what we do, the concepts of classical electromagnetism are a good description. That means Maxwell's four equations apply, and electric and magnetic fields are distinct quantities. There is no need to talk about virtual photons mediating the force; that is from the quantum world.

But you do agree, no matter how you look at it, that electrons move slowly around a wire when a current flows, right?

[Mike Sulzer]

That should be "along a wire", not "around a wire".

[dazzlindino]

So with that being said, magnets, coils, gauge, poles actually add up to force X, correct?
In other words , a pickup changes an acoustical force into an electronic force.
A pickup does not read "tone", only sends a pulse / force through to an amp.
Point is this there would be hundreds of ways to come up with the same force in said X, it would be easier to acheive the same tone using the same mtrls, but not neccesary, yes / no / hell no?

[Mike Sulzer]

So with that being said, magnets, coils, gauge, poles actually add up to force X, correct?
In other words , a pickup changes an acoustical force into an electronic force.
A pickup does not read "tone", only sends a pulse / force through to an amp.
Point is this there would be hundreds of ways to come up with the same force in said X, it would be easier to acheive the same tone using the same mtrls, but not neccesary, yes / no / hell no?

To me it makes more sense to say that a pickup produces electrical voltage and current that represents the vibration of the string at some level of accuracy.

[David King]

Think of moving electrons as being similar to water in a hose. If the hose is full (a conductive material) when you turn the water on at one end -the water comes out the other end instantaneously but the actual water molecules at the hose bib take a while to come out the other end.

[David Schwab]

There is no need to talk about virtual photons mediating the force; that is from the quantum world.

I know... I just like the quantum world. ;) It's just cool looking at the minute stuff that's behind the big stuff.

But you do agree, no matter how you look at it, that electrons move slowly around a wire when a current flows, right?

Absolutely. Electrons are the thang.

[David Schwab]

Think of moving electrons as being similar to water in a hose. If the hose is full (a conductive material) when you turn the water on at one end -the water comes out the other end instantaneously but the actual water molecules at the hose bib take a while to come out the other end.

I always liked the marbles in a long hose analogy.. the hose if filled with marbles from end to end... you stick a new one in one end, and one pops out the other.

Except the electrons never really leave the wire. :eek: