Magnets & Copper Wire: A Pickup Building Thread

[slowburnaz]

Just an added tidbit... I saw somewhere once that it's also best to use the `start` of any coil as the lead that connects to ground. I've done that by convention ever since, but can't back that up with any rigorous scientific reasoning.

 

[RichterScale]

Just an added tidbit... I saw somewhere once that it's also best to use the `start` of any coil as the lead that connects to ground

But then if you need to flip the current direction on a 2nd coil, you'd wire the start lead as +, correct?
Or is it more complicated?

 

[Will_White]

But then if you need to flip the current direction on a 2nd coil, you'd wire the start lead as +, correct?
Or is it more complicated?

With two coils wound the same direction, yes.

 

[slowburnaz]

But then if you need to flip the current direction on a 2nd coil, you'd wire the start lead as +, correct?
Or is it more complicated?

Only if you choose to wind the coils the same direction. On any humbucker I make, I've stuck with the standard of CCW/North polarity up on one coil (I make this the "neck"-most coil), and CW/South polarity up on the other (I make this the "bridge"-most coil). That's just so that no matter what pickups I end up making, if someone mixes and matches, they'll always be in phase as long as I'm consistent with the color coding.

And as such, my start leads are always the ones that go to ground.

 

[RichterScale]

Yeah, I think that would be hard to keep track of for me, not to mention, not having a winder.
If it's functionally the same to wind every coil/bobbin in the same direction, with the start and end leads all being the same and then just reverse whether it's +/-, then I'd do that to start.
I'm hardly ready to be having this conversation, let alone level 5 pickup nerd stuff

 

[Fred Miller]

... And as such, my start leads are always the ones that go to ground.

I woulda thought, having the end lead go to ground and the start lead hot would be best, as the outer windings would act as a shield for the inner windings. Has anyone experimented with this?

 

[Kinkh]

I woulda thought, having the end lead go to ground and the start lead hot would be best, as the outer windings would act as a shield for the inner windings. Has anyone experimented with this?

The outer windings won't shield from anything since they are electrically still part of the coil. If you would want some windings to act a as a form of shield, then you would need the extra winding connected only to ground. Which is exactly what a copper tape shield is - a single, grounded winding on the outer side of the pickup... And that's something pickup makers tend to use.

 

[RichterScale]

Folks, I apologize in advance for an even more rudimentary question, but I googled it and immediately clicked away from the asinine things that google decided were useful. Anything from "one needs a battery and one doesn't", to "tonewood" being mentioned. Not kidding. This is just the first dozen results. I didn't click on any of them. Dear Lord, is there something in the water?
Anyway, just the simplest question and I just wanna hear it from the horse's mouth:
Generally speaking, are pups made for an active system constructed differently than pups intended to be passive? Perhaps wire gauge, wind count, etc?
I know there's a lot of variables, just wondering if there's a general approach for building one or the other.

 

[Jeff Siddall]

Generally speaking, are pups made for an active system constructed differently than pups intended to be passive? Perhaps wire gauge, wind count, etc?
I know there's a lot of variables, just wondering if there's a general approach for building one or the other.

In general, yes, active pickups are constructed differently, but mainly because they can do different things with them knowing they are [typically] going to be amplified at least one more time than passive pickups, and possibly EQ'd too. Often this means lower turn count and stronger magnets.

 

[Fred Miller]

If you were a commercial manufacturer with a reputation to uphold, you'd probably design pickup and preamp together, and do lot of testing with different combinations of the main variables, then bring in focus groups, hire marketing consultants etc. Then of course the accounting dept. would tell you it couldn't be made for less than the national debt of a large first world country...

 

[RichterScale]

In general, yes, active pickups are constructed differently, but mainly because they can do different things with them knowing they are [typically] going to be amplified at least one more time than passive pickups, and possibly EQ'd too. Often this means lower turn count and stronger magnets.

Thank you. Obviously, I'm starting at the beginning beginning with all this.
If we are talking strictly in terms of physical size, can you wind them with less wire to the point that you gain substantial advantages in size and shape options?
Or, for your typical pups, is there not much difference in the amount of copper used?

 

[Jeff Siddall]

Thank you. Obviously, I'm starting at the beginning beginning with all this.
If we are talking strictly in terms of physical size, can you wind them with less wire to the point that you gain substantial advantages in size and shape options?
Or, for your typical pups, is there not much difference in the amount of copper used?

I haven't seen any active pickups that are physically smaller than passive, though I am sure they must exist. Normally the active pickups have been underwound to help with clarity/brightness. This works, but results in a quieter pickup. As a passive pickup, that could be unacceptable, but in active pickups you can offset that loss in gain. The pickup could also become over-trebly (if that's a word) but again, you can compensate that.

 

[RichterScale]

Thanks again.
I saw an EMG preamp that advertised as working with either active or passive and that led me to the questions.
That, and I'll need to build or have built a custom 6 string pup for the next bass and didn't know where to begin.
I don't want to tie up this thread too much, but this is the only place to get any useful answers about this stuff. (At least that I know of)

 

[Fred Miller]

Generally, a preamp will improve the sound of any pickup. By better matching impedances, less treble is lost due to the capacitance of the coils, and less loss due to the capacitance of the cable to the amp. But there'll always be someone who prefers the passive sound.

 

[Bruce Johnson]

Generally, a preamp will improve the sound of any pickup. By better matching impedances, less treble is lost due to the capacitance of the coils, and less loss due to the capacitance of the cable to the amp. But there'll always be someone who prefers the passive sound.

Yes, but it depends on how you define "improve". There are tradeoffs when you add a preamp into the circuit. I'm a Passive Only type. I build my pickups to be powerful enough that they can operate without a preamp. Specifically because I don't want the filtering effects of the preamp. I build my basses, shaping the tone through the mechanical frame, and I make my pickup system with as much range and clarity and flat EQ as I can. I don't want the electronics to manipulate the sound.

I realize that most builders do the opposite. They ignore or deaden the effect of the frame, and shape the sound with pickups and preamps. That's their choice.

 

[Fred Miller]

Yes, but it depends on how you define "improve".

Yes, how you define "improve" is a matter of opinion.

And whatever you plug your instrument in to is going to have a preamp, and the best place to have one is as close to the pickup as possible.

 

[RichterScale]

Yes, but it depends on how you define "improve". There are tradeoffs when you add a preamp into the circuit. I'm a Passive Only type. I build my pickups to be powerful enough that they can operate without a preamp. Specifically because I don't want the filtering effects of the preamp. I build my basses, shaping the tone through the mechanical frame, and I make my pickup system with as much range and clarity and flat EQ as I can. I don't want the electronics to manipulate the sound.

I realize that most builders do the opposite. They ignore or deaden the effect of the frame, and shape the sound with pickups and preamps. That's their choice.

Bruce, I don't have much of an opinion on this subject either way. So, I have a fresh, corruptible mind on the subject. As it stands, the only reason I would pick an active system is because there's no way I can know what a bass would sound like until it's finished. I just don't have the experience to influence the final sound through the construction process alone. So, it would be nice to have that little bit of extra electronic help to boost or hide any deficiencies in the overall final sound of the bass. Other than that, I thought the idea of the filter based pre like the distiller would be fun to play with.
Anyway, that's all neither here nor there. I don't prefer active or passive.
On your pickups: Is there a LOT of extra copper on there? As in, does it take a large or small % of extra wire to notice big changes? Not looking for specifics or proprietary secrets or anything. Just a feel for the basics.

 

[Fred Miller]

Specifically because I don't want the filtering effects of the preamp.

A well-designed preamp can have a flat response from dc to way above the range of human hearing.

 

[Will_White]

A well-designed preamp can have a flat response from dc to way above the range of human hearing.

This is where a buffer only preamp comes in handy, you have the same interactions of passive controls, it's more consistent between different inputs and you don't have to worry about cable length.

 

[Bruce Johnson]

Bruce, I don't have much of an opinion on this subject either way. So, I have a fresh, corruptible mind on the subject. As it stands, the only reason I would pick an active system is because there's no way I can know what a bass would sound like until it's finished. I just don't have the experience to influence the final sound through the construction process alone. So, it would be nice to have that little bit of extra electronic help to boost or hide any deficiencies in the overall final sound of the bass. Other than that, I thought the idea of the filter based pre like the distiller would be fun to play with.

That's exactly the attitude of most bass builders and manufacturers. It's much easier to adjust the sound with the electronics. Less R & D and experimenting. That's what Leo did with his basses. He wanted to manufacture them by the millions and have their sound be consistent. He designed the frame of the P-bass to be simple and cheap to manufacture, and to not have much effect on the sound. Then he developed the P-bass pickup specifically to shape the sound it reads on the strings. That's why the sound of most P-basses comes mostly from the pickup and the strings. That was his intention: Cheap to manufacture, pretty good sound, and consistent from one to another.

But then, reality intervened....Players started noticing that some P-basses were sounding better or worse or different due to.....small differences in the construction of the frame! How can this be??? Hilarity ensues. A cottage industry develops making replacement pickups to adjust the sound of P-basses in different ways. And teams form up debating the effects of different Tone Woods! And Leo is up there somewhere, chuckling....

On your pickups: Is there a LOT of extra copper on there? As in, does it take a large or small % of extra wire to notice big changes? Not looking for specifics or proprietary secrets or anything. Just a feel for the basics.

No, I don't put a lot of extra copper in my pickups. I increase the output level of my pickups by increasing the strength of the magnetic field. Big honkin' magnets, man. Increasing the number of turns of wire will generally make a bigger lump in the frequency curve. I don't want that. I want to keep the frequency curve relatively flat. I keep the number of turns fairly low, and use larger gauge wire to keep the resistance low. And I make my coils tall and narrow, wrapped tightly into the most powerful part of the magnetic field. That's for the clarity and range. That's my Secret Formula. Which I've been publicly explaining on this thread from the beginning.