Magnets & Copper Wire: A Pickup Building Thread

[rudy4444]

The back story on Jason re-releasing his winder book was always interesting to me. I paid less than $100 for an original copy and sold it for what I paid after I read it. Some unscrupulous folks were starting to sell photocopies of the original, and that was just plain wrong. I was glad when Jason re-released his winder manual because at least it stopped some of the dishonest sellers from making money on what was rightfully his work. At the time it was a hard decision to wrestle with, because he had inadvertently created competition for his own pickups by providing information to folks who were getting interested in winding.

At the time the Lollar book was published the internet information just wasn't as commonly available as it is nowadays.

The winder book was available at our library as an inter-library loan, but I didn't want to limit myself with a two week window to glean everything I wanted to get out of it. It did have flat work patterns and other useful info beyond the winder building instructions. I ended up winging it and made a perfectly functional winder from a brand new $15 bargain bin electric drill.

I used a couple of his Chicago Specials in my lap steels when requested by folks ordering custom laps from me, and they have Jason's mojo in spades. His motto should read "Often imitated, but never duplicated".

I also purchased the only other book that had any usable information in it when it was first released, and still have that one laying around here somewhere:
https://www.amazon.com/Pickups-Wind...ocphy=9057525&hvtargid=pla-453391868600&psc=1

 

[dwizum]

Just to be clear - in case anyone misconstrued my comments above - I would never actually try to make money off stockpiling someone else's book like that!

 

[Freekmagnet]

Has anyone read the Animal Magnetism book? I was thinking about ordering a copy.

 

[slowburnaz]

Has anyone read the Animal Magnetism book? I was thinking about ordering a copy.

Yup. It's pretty cool, and has a few different designs in it that he details. Hell, it even goes over making an entire bass...

Depending on how much you can get it for, its worth it just to have, if nothing else, IMO.

 

[Freekmagnet]

Yup. It's pretty cool, and has a few different designs in it that he details. Hell, it even goes over making an entire bass...

Depending on how much you can get it for, its worth it just to have, if nothing else, IMO.

He sells the book on his website. He charges more for shipping than the cost of the book.

 

[slowburnaz]

He sells the book on his website. He charges more for shipping than the cost of the book.

Yikes! Maybe the pages are made from lead.

 

[Freekmagnet]

Yikes! Maybe the pages are made from lead.

Nope, copper hahaha!

 

[Matt Liebenau]

Has anyone read the Animal Magnetism book? I was thinking about ordering a copy.

I read it a long time ago. I think I still have it around the house somewhere.

 

[Bruce Johnson]

Has anyone read the Animal Magnetism book? I was thinking about ordering a copy.

Yes, I have a copy of Animal Magnetism that I bought back in the '90's, around the same time I got Jason's book. I learned more useful info from Animal Magnetism. Jason's book is mostly about building a simple little winder with hand tools, and the basics of how to wind wire on classic style bobbins. Beginner-level stuff. Not much about the more complicated parts of designing and building pickups.

Animal Magnetism shows how the author builds some unusual bass pickups from scratch. Not wide coverage of alternate pickup designs, but good detail on his particular design and process. What you are doing now, Jeremy, is more advanced than what he covers in his book. It's a good book, but I'm not sure you would learn much from it. You are past that already.

 

[ardgedee]

I'm really not interested in experimenting with lower TPL rates and making looser sloppy coils.

I have a question about packing wire as close to the coil as possible. Would it be advantageous to make pickups taller (that is, the core is taller and the bobbin around the core fits more strands per layer), so that a 6,000 turn coil would have more copper closer to the core than a conventionally-sized pickup, or would it be a waste of metal? Granted there are practical limits due to instrument design anyway since a coil more than an inch and a half tall might go entirely through the body. And anyway I'm not likely to build pickups any time soon so this is just an idle thought.

 

[Freekmagnet]

I have a question about packing wire as close to the coil as possible. Would it be advantageous to make pickups taller (that is, the core is taller and the bobbin around the core fits more strands per layer), so that a 6,000 turn coil would have more copper closer to the core than a conventionally-sized pickup, or would it be a waste of metal? Granted there are practical limits due to instrument design anyway since a coil more than an inch and a half tall might go entirely through the body. And anyway I'm not likely to build pickups any time soon so this is just an idle thought.

The general axiom is:

taller, narrower coil = brighter, more focused sound

shorter, wider coil = fatter sound

something like that. I don’t know that it’s a question advantageousness as opposed to what the pickup designer is trying to achieve. Some guys might argue that having more copper closer to the coil is more “efficient”, but as far as weather or not a more efficient pickup makes a better-sounding pickup is completely subjective.

 

[dwizum]

I do think it begs a question though. Which relationships matter in terms of determining the sound? The magnet creates a magnetic field. We sometimes use slugs or bars of steel to help shape the field. And then we put both a wire coil and a string somewhere in the field. I suppose you could distill it to three elements - the magnetic field, the coil, and the string. Is it possible to change the relationship between two of those without impacting the third?

In other words, if you change the coil shape from short and fat to tall and narrow, you may be putting more copper in closer to the magnet, but you're also changing the relationship between the copper and the string, right? Does that matter?

I'm not sure if I'm even formulating my question well here...

 

[Freekmagnet]

I do think it begs a question though. Which relationships matter in terms of determining the sound? The magnet creates a magnetic field. We sometimes use slugs or bars of steel to help shape the field. And then we put both a wire coil and a string somewhere in the field. I suppose you could distill it to three elements - the magnetic field, the coil, and the string. Is it possible to change the relationship between two of those without impacting the third?

In other words, if you change the coil shape from short and fat to tall and narrow, you may be putting more copper in closer to the magnet, but you're also changing the relationship between the copper and the string, right? Does that matter?

I'm not sure if I'm even formulating my question well here...

All of the relationships matter to some degree. Shape of the coil, magnetic material, size of the magnet, number of winds, gauge of the wire, etc. They all have an effect on the overall sound.

Given all the variables on the table, I think pickup placement probably would have the most drastic effect on how the pickup sounds.

 

[Bruce Johnson]

I have a question about packing wire as close to the coil as possible. Would it be advantageous to make pickups taller (that is, the core is taller and the bobbin around the core fits more strands per layer), so that a 6,000 turn coil would have more copper closer to the core than a conventionally-sized pickup, or would it be a waste of metal? Granted there are practical limits due to instrument design anyway since a coil more than an inch and a half tall might go entirely through the body. And anyway I'm not likely to build pickups any time soon so this is just an idle thought.

Yes, that's an important factor in the design of pickups. Making the bobbin taller and narrower and pulling the turns of wire tighter around the magnets gives the pickup higher definition and clarity. Making a coil short and fat makes the sound more muffled and blurry. The reason is because, as you build up more turns out at a farther radius, the length of wire of each turn gets longer. Every time a magnetic field line swings through the coil, there is a longer delay in the signal pulse going through the outermost turns and the innermost turns. The summation of the pulses (the overall signal) becomes more blurry.

That's a main difference between standard P-pickups and J-pickups. P-pickups are short and wide; J-pickups are tall and slim. P-pickups are designed to sound thick and somewhat fuzzy on purpose. J-pickups are designed to be more clear and high definition.

Some pickup makers, like me, push the clarity and definition thing even farther. My AMB-2 pickups use very large tall, powerful magnets. My coils are about an inch tall, and are wrapped densely and in close around the magnets. I do this for very wide frequency range, clarity and high definition.

 

[Bruce Johnson]

I do think it begs a question though. Which relationships matter in terms of determining the sound? The magnet creates a magnetic field. We sometimes use slugs or bars of steel to help shape the field. And then we put both a wire coil and a string somewhere in the field. I suppose you could distill it to three elements - the magnetic field, the coil, and the string. Is it possible to change the relationship between two of those without impacting the third?

In other words, if you change the coil shape from short and fat to tall and narrow, you may be putting more copper in closer to the magnet, but you're also changing the relationship between the copper and the string, right? Does that matter?

I'm not sure if I'm even formulating my question well here...

I'll refer you back to page 2, post #40 of this thread:

There are two halves to the "aperture" thing; shaping the sound:

One is how the magnetic field surrounds the moving string. That includes how powerful the magnetic field is, the size and shape, and how it's located around the motion of the string. All this is mostly about the magnets and pole pieces (if any); size, shape, position, magnetic power. How the motion of the string is transferred into making the magnetic field wiggle.

The other part is how the coil fits within the other end of the magnetic field. This determines how the wiggling magnetic field creates a wiggling electrical signal within the coil. This is where coil geometry comes in; tall, narrow, short, wide, densly-packed, scatter-wound, etc. Where the turns are within the field. That affects the amplitude of the signal, the clarity of the signal, and shift of the frequency curve.

If you look at a basic standard Fender-style magnetic pickup, with a row of Alnico rods standing up vertically, the magnetic field shape is pretty simple. In that case, a tall, narrow, dense coil (like a Jazz) packs the wires in around the densest part of the magnetic field. That makes a big, clear, relatively clean signal. The Jazz sound. Put a short, wide looser coil (like a P-bass) around that same magnetic field, and half of the turns of wire are hanging out farther away from the dense core of the magnetic field. The signal buildup in the coil gets more confused and muddy, and the frequency curve gets a bigger lump. The P-bass sound. That's an example of how the geometry of the coil, in relation to a simple magnetic field, is used to shape the sound.

When you get into sidewinders, it gets crazier, because the magnetic field shape gets complicated. You have to understand what that shape is and where it's most dense and powerful. Then design the shape of the coils to fit to that. And adjust them to shape the sound.

The overall point here is that the geometry in the positioning of the string, magnetic field, and coil is where the real action is in shaping the sound of a magnetic pickup. If you want to experiment with pickups, you have to make custom parts to move the geometry around. So much of magnetic pickup design is mechanical.

The coil doesn't "read" the string. The magnetic field "reads" the string and starts wiggling. The coil sees the wiggling magnetic field and makes a wiggling electrical current in its wire. It's a two stage thing.​

 

[BunchyMutt]

Yes, that's an important factor in the design of pickups. Making the bobbin taller and narrower and pulling the turns of wire tighter around the magnets gives the pickup higher definition and clarity. Making a coil short and fat makes the sound more muffled and blurry. The reason is because, as you build up more turns out at a farther radius, the length of wire of each turn gets longer. Every time a magnetic field line swings through the coil, there is a longer delay in the signal pulse going through the outermost turns and the innermost turns. The summation of the pulses (the overall signal) becomes more blurry.

That's a main difference between standard P-pickups and J-pickups. P-pickups are short and wide; J-pickups are tall and slim. P-pickups are designed to sound thick and somewhat fuzzy on purpose. J-pickups are designed to be more clear and high definition.

Some pickup makers, like me, push the clarity and definition thing even farther. My AMB-2 pickups use very large tall, powerful magnets. My coils are about an inch tall, and are wrapped densely and in close around the magnets. I do this for very wide frequency range, clarity and high definition.

Do these electrical principles mean that the opposite is true with sidewinders (since tall, narrowly-wound coils when turned on their side would put coils further away from the magnet than squatter, wider coils)?

 

[ardgedee]

taller, narrower coil = brighter, more focused sound
shorter, wider coil = fatter sound

Fair enough, but that's more than one parameter changed.

Not sure if I was being ambiguous or misunderstanding the terms of art when I said 'taller'... How would two pickups built with the two bobbins below differ in output or sound quality, if at all, given the same wire, same number of winds, same aperture, if the only difference was one was taller? The substantive changes was the taller one would have more wire closer to the core (but more wire would also would be farther from the string*), and the core itself would be taller (more ferrous and/or magnet mass, depending on whether the magnet is in the core or under it).

Some pickup makers, like me, push the clarity and definition thing even farther. My AMB-2 pickups use very large tall, powerful magnets. My coils are about an inch tall, and are wrapped densely and in close around the magnets. I do this for very wide frequency range, clarity and high definition.

Okay, this gets closer to what I was wondering. How would the sound differ if your coils and magnets were 3/4" tall or 1.25" tall, but the number of wraps and bobbin dimensions were in other regards the same?

*(EDIT: Bruce answers this part of the question in post #435. Thanks!)

 

[ardgedee]

The funny thing is it feels like a silly issue but it's gotten stuck in my mind now. I'm happy and thankful to the brain trust here for fielding these oddball questions.

 

[Bruce Johnson]

Do these electrical principles mean that the opposite is true with sidewinders (since tall, narrowly-wound coils when turned on their side would put coils further away from the magnet than squatter, wider coils)?

No, not usually, but it depends on how the magnet structure is made. In most sidewinders, the magnets run horizontally through the center of the coils. Pole plates or pieces at the ends extend the magnetic field up to the strings. So, the field is kind of L-shaped or U-shaped, with the coil wrapped around the middle. The same principles on coil geometry apply. Making the coil compact and wrapped tightly around the field will make the sound more focused and clear. Making the coil fatter and spread out from the field will make the sound more soft and fuzzy. But, it can get complicated when you bend the magnetic field around into shapes.

 

[BunchyMutt]

No, not usually, but it depends on how the magnet structure is made. In most sidewinders, the magnets run horizontally through the center of the coils. Pole plates or pieces at the ends extend the magnetic field up to the strings. So, the field is kind of L-shaped or U-shaped, with the coil wrapped around the middle. The same principles on coil geometry apply. Making the coil compact and wrapped tightly around the field will make the sound more focused and clear. Making the coil fatter and spread out from the field will make the sound more soft and fuzzy. But, it can get complicated when you bend the magnetic field around into shapes.

Fascinating. Thanks!