Why do the various grades of alnico sound different?

[Folkcafe]

Guilty as charged

I throw myself on the mercy of the court.

For me this was not a practical exercise. Instead really a mental exercise (that can be taken any number of ways).

Just for clarification. I was only looking at Alinco 2 formulations and processing and was trying to understand why there would tonal variances between the same grades of magnets from different manufacturers. On the surface, it simply didn't make sense to me. So I have developed some far fetched and perhaps reasonable theories over the last couple of days.

I did learn a little while spinning my wheels and my brain hurts a bit. Looking at papers about phase decomposition is not exactly light reading

Tomorrow is another day. I have parts arriving via ups to finish the modifications to the winder. Then I can focus on building pickups again.

I really need to cut back on the Sunday morning coffee.

[Possum]

....

The simple answer is that none of them are using the same recipe. And probably variations in methods, but mostly the recipe. This is a GOOD thing. Some companies' alnico 2 sucks and some is awesome. I have probably have five varieties of alnico 2 here myself to use for various pickups. Fit the magnet to the pickup and forget about what grade its called

[tonedeciple]

Now that's what I call feedback! Never the less, I do have a better understanding of the why. A magnet's composition affects the eddy currents and inductance, which helps to shape a pickups tone. That's about as far as I need to go. At least now I can give a reasonably intelligent answer when some one asks me why an A5 sounds different than an A2. In the past I always mumbled something like, "one is more magnetic than the other." Ouch!

[Possum]

...

Just tell them there are more chocolate atoms in alnico 2 than 5....

[Folkcafe]

The simple answer is that none of them are using the same recipe. And probably variations in methods, but mostly the recipe.

If by recipe, you mean chemistry, I thought the same thing at the start of this. Now I am not convinced that slight variations of say 16.8% FE vs 17% would net a tonal difference you could hear all by itself.

When I looked past the formulation and into the process of making magnets, the first questions I had was why the rapid cooling and tempering. Usually these processes are for changing the mechanical properties of a material. Why would anyone care about the hardness or wear factor of a magnet? As I looked further, I learned that these processes affect and enhance the magnetic properties of the material. Another "Doh!" moment.

Quenching slowly allows the formation of a greater number of non-magnetic phase regions. The faster you cool, the less you have. Tempering also greatly affects the magnetic properties. Vary these processes and you have a great deal of variance in the magnetic properties of the end material.

My conclusion (take it with a grain of salt, I'm a two day expert in the field) is that process has a greater affect on the magnetic properties than minor variations of chemistry.

I wanted to know, like many here, if there were variables that could be specified in the manufacture of magnets. The conclusion I have reached is that from a practical point of view, there is not. The number of variables that have a direct impact on the magnetic properties of a magnet are too great for a simple solution such as "change this one thing". (sometimes you just have to find some answers on your own)

A large client might have enough sway to insist on tight controls on the methodology of production but I doubt you or I could do so.

As you have very eloquently stated, you have to find the right magnet for your pickup and move on. (I'm paraphrasing) I've found the answer I was looking for and I'm moving on. As you were the one that inspired me with the idea of "recipe" (repeatedly), I thank you.

Anyone looking for where I started to come to a conclusion on this, simply search "Phase chemistry and properties of Alnico 2 permanent magnets". The one paragraph "Discussion" at the end was insightful but there are little nuggets throughout if you can figure out what to search for.

[FunkyKikuchiyo]

What Possum said is interesting.... what changes is the big chunk of metal. Considering the big differences you can get by changing slugs, baseplates, keepers, etc. that does make sense.

I think of something like the DiMarzio Air series, where they put in gaps instead of degaussing, and you end up with something entirely different than if you had simply degaussed or used a "weaker" alloy. I haven't found a good explanation for that yet.

But Mesa, I'm not sure how oersted and gauss can not vary proportionately. Strength of a magnetic field and density of a magnetic field are very closely related, right? A field becomes strong by being dense, it seems like they would always go hand in hand. The only way you could violate that is by using dissimilar magnet sizes. Or, am I wrong? Or, are you talking more about BH curve stuff?

[David Schwab]

I think of something like the DiMarzio Air series, where they put in gaps instead of degaussing, and you end up with something entirely different than if you had simply degaussed or used a "weaker" alloy. I haven't found a good explanation for that yet.

Have you read their patent (5399802)?

They state:

These prior art arrangements are characterized in that the permanent magnet element is in direct contact with the pole pieces to provide a strong magnetic field. It is known in the art that variation in tonal quality can be achieved by changing the strength of the magnetic field in which the strings vibrate. As will be understood, the magnetic field tends to dampen the vibrations of a string; the stronger the field, the greater the damping. Differences in the damping factor will affect qualities of the sound generated by the strings, such as the length of the note generated, referred to as the "sustain" and distortion. To the musician, reduction in the damping effect by a limited amount will produce a more pleasing musical sound. However, in the past, this has been accomplished by reducing the field strength of the permanent magnet employed in the pickup in ways that have produced undesirable side effects.

In one such expedient, magnetization of the permanent magnet material is calibrated such that the material is magnetized to less than the maximum possible field strength. Magnets so produced suffer from the tendency to lose magnetic strength relatively quickly, thus affecting sound quality and requiring replacement more frequently. Another expedient is to use an alloy having a weaker field strength, such as Alnico 2 or 3, in place of the stronger field strength and less costly, Alnico 5.

SUMMARY OF THE INVENTION

It is the object of the present invention to provide an electromagnetic pickup for musical instruments in which the magnetic field strength is reduced by a predetermined desired amount to enable the instrument with which it is used to produce more pleasing tonal qualities.

In accordance with the present invention, the controlled reduction in magnetic field strength is achieved by providing a predetermined non-magnetic gap or spacing between the permanent magnet element, preferably made of Alnico 5, and the ferromagnetic pole pieces...

By appropriate placing of the pole pieces on the retainer bar, the gap between the pole pieces and the magnet may be precisely determined. Different spacings may be selected to provide different tonal qualities.

So it seems it was a way to get a similar tone as degaussed mags, or other grades of alnico, while still using a fully charged alnico 5. For a big factory, that means less work with degaussing magnets, and a simpler inventory of magnets used.

[Ronsonic]

Have you read their patent (5399802)?


So it seems it was a way to get a similar tone as degaussed mags, or other grades of alnico, while still using a fully charged alnico 5. For a big factory, that means less work with degaussing magnets, and a simpler inventory of magnets used.

It also means consistency and repeatability. No more fussing with inconsistencies like partial charging or dealing with less stable magnet materials. That fully charged A5 and a 0.0XX shim will be the same on every pickup and likely stay that way for years.

I don't know if it makes for a significantly better pickup, but better is a matter of taste. It does mean they can make thousands of them that sound the same.

[David Schwab]

It also means consistency and repeatability.

Yes, I forgot to mention that.

[RedHouse]

I think we would be able to answer these questions ourselves if we knew WHY magnet composition affects tone. In other words what's actually happening to the tone when a magnet is change from one composition grade to another.

It easy to state that changing the composition changes different tone, but apparently it's much harder to say exactly why or what's happening to cause this. I've done a little research myself in the last day or so and no one seems to have a concise answer.

I don't agree really.

This would be just like that tired-old eddy currents thing, lots of heat/friction/smoke but no light. It's enough that we know they sound different, we should be using our ears and winding skills to make tone happen not so much chemistry/physics recipies.

Ever see an old violin maker select a piece of wood for a top? absolutely no time spent discussing tree growth patterns, carbon content, yearly ring density etc, he grabs a piece and taps on it with his finger, using his ear and experience he knows when he has the right piece when it sounds right.

[David Schwab]

I don't agree really.

This would be just like that tired-old eddy currents thing, lots of heat/friction/smoke but no light.

You can't hear light. You can hear eddy currents. Take a humbucker stick a cover on it. How does it sound?

Ever see an old violin maker select a piece of wood for a top? absolutely no time spent discussing tree growth patterns, carbon content, yearly ring density etc, he grabs a piece and taps on it with his finger, using his ear and experience he knows when he has the right piece when it sounds right.

Don't forget that the wood piles he's going through was already sorted for various attributes like how close the rigs are and stiffness.

You certainly can get a lot of tones out of one set of parts, but you can also get many more tones from other parts.

Gut instinct and experience count for a lot too!

[RedHouse]

You can't hear light.

It's one of those old armchair euphemisms, but never mind.

...Take a humbucker stick a cover on it. How does it sound?

You're preachin to the chior David, that was exactly my point "how does it sound", ...make notes, ...and move forward but never mind.

...Don't forget that the wood piles he's going through was already sorted for various attributes like how close the rigs are and stiffness....

As are our magnets and covers, but the ear is the tool.

[FunkyKikuchiyo]

I was under the impression that part of what made the air series sound unique was that gap, they tend to have more harmonics, a more dynamic midrange.... maybe it is just because dimarzio normally doesn't incorporate weaker magnets in their designs? That certainly explains a lot, then.

[Possum]

....

The air gap thing definitely gives a tone thats different than degaussing a magnet. Unfortunately I think they use the air gap thing in their PAF repros, which is totally ridiculous and ensures the pickup will never sound like a real PAF That and the brass baseplate used on same. Yes the heat treat, tempering thing for sure will change the sound of the magnet etc. same thing for steel, and is one reason manufacuter's different steel batches sound different too, that and how much compression is used in cold drawing. I"m sure magnet making is a very super complicated process and modern processes are probably nothing like what they did in the 50's. About the only thing you might have some control over is to find a magnet you really like and send it to a magnet company and ask if they can reproduce it. I wonder if they actually could since methods aren't the same and I'm sure they're not using similar raw materials as used in the 50's.

[David Schwab]

DiMarzio uses nickel silver baseplates on their PAFs. Right now the only PAF they have is the 36th Anniversary model. They also claim that the covered models use nickel silver covers plated with no copper.

Their PAF is a real interesting design though, rather than copy a real PAF in the way it's made, they say:

These pickups are not merely clones. We re-engineered the PAF® using our patented technology and Larry DiMarzio’s own 1959 cherry sunburst Les Paul® as the reference. Larry’s Les Paul® has a uniquely amazing sound and it’s not only due to the pickups - it’s the total fusion of many elements of the guitar itself.

My buddy had one and had to switch the baseplate with a different one because of the way he was mounting it. The slugs are shaped just like the screws, with a narrow shaft and a wider head. They had extra slugs installed between the string sensing slugs and screws to increase the inductance, and then they had the spacers on the four outside screw/slugs to keep the magnet a certain distance. They used small nylon washers. The magnet was glued to the bottom of the pickup.