Pole length on pickup and it's effect

[sirmuppet]

On 10/04/2023 at 03:03, Baloney Balderdash said:

I am pretty certain that the basic point of the OP is following:

 

If you got 1 magnet of a certain given strength, then cut/split it, so that you now got 2 magnets, but not exactly in half (50/50), but lets say one piece is 60% the size of the original magnet and the other piece is 40% of the original magnet's size, will the two pieces then have exactly equal strength or will the piece that is 60% of the original magnet be stronger than the piece that is only 40% of the original magnet, given the strength is measured from a given isolated identical surface area, say the two ends respectively at which they were cut from the bigger original magnet?

 

Yes exactly this! 😁

 

 

On 10/04/2023 at 08:49, itu said:

Dear Baloney, I think your comment includes the original, although a theoretical question. But magnets are produced in big amounts and the tolerances already dictate the strengths. Magnetizing - which has also tolerances - produces components that are then selected to represent certain specs.

 

A magnet is not ideal, because materials and production methods are not ideal. There's no one magnet that represents all similar sized magnets, except that it's more or less magnetic.

Interesting to know tolerances could vary so much. Noted and thanks 👍

 

 

18 hours ago, ikay said:

As itu says, there are many factors involved in the strength of the magnetic field in any given magnet. However, I think the simple answer to the original post is probably yes. If the poles are of the same material and charged in the same way for the same length of time, the longer magnet contains more magnetic material (domains) that can be aligned and therefore the potential to produce a slightly stronger field. In practice the difference is probably negligible. The proximity of the magnet to the vibrating string will have a much greater effect on the strength of the signal being produced. The purpose of the longer D and A poles is to do exactly that, by compensating for the curvature of the fretboard and therefore the D and A strings being higher above the pickup.

 

https://sciencing.com/causes-different-strengths-magnets-5981925.html

Does the size of a magnet affect its strength? The short answer is yes, but only because the size of a magnet means that there are proportionally more domains that can align and produce a stronger magnetic field than a smaller piece of the same material.

This and the above answers my question.

 

Thanks all.

[Andyjr1515]

On 06/04/2023 at 12:41, sirmuppet said:

Here's a diagram I just made to illustrate my question.

 

 

 

OK - I think I now understand the question but the answer is 'it depends'. 

 

First a couple of things that are relevant, because the answer can be different in each case:

 

- In some pickups, the slugs themselves are individually magnetised

- In other pickups (such as the Entwistles above), the slugs get their magnetism from the bar magnets stuck to the bottom of the pickup.  The slugs themselves are not permanent magnets - put them near or against  the bar magnets and they will become magnetic; take them out and they will not be magnetic.

 

 

In the case that the slugs themselves are magnetised:

The length of the slug is irrelevant - the strength of the magnet is determined by the amount it has been magnetised in manufacture (the gaussing process).  So, all other things being equal, the longer slugs will be the same magnetism as the short slugs.  

In your diagram, however, you have increased the distance from the strings of the four middle slugs.  So in your above example, the longer slugs will usually be the same magnetism as the shorter outer ones, but the pull on the strings will be less.

 

In the case of non-permanently magnetised slugs with bar magnets again, it depends.  If all the slugs use the full depth of the bar magnets, then, again, there will be no difference at all from the length difference of the slugs - only, again, the effect of the distance from the top of the slug to the string.

However, if any of the slugs are lifted so that they are not fully covered by the depth of the bar magnets, then there will be a slight change in the magnetic field - although generally not great enough to be audible - until and unless they are raised to the point that they have been lifted away from the bar magnets altogether.

 

 

Ref your question on the diagram, 

Same distance from strings = same pull

Longer slugs 'more mass', but gaussed to the same level of the others = same pull

Edited April 11, 2023 by Andyjr1515

[Andyjr1515]

5 minutes ago, sirmuppet said:

Yes exactly this! 😁

 

 

Interesting to know tolerances could vary so much. Noted and thanks 👍

 

 

This and the above answers my question.

 

Thanks all.

Great - you posted this while I was posting mine

 

[sirmuppet]

19 hours ago, Andyjr1515 said:

Great - you posted this while I was posting mine

 

Sorry man but your answer you posted while I did was perfect. 

 

The reason I was asking is I had a set of pickups custom made. We had the middle poles radiused the same as a 7.25 vintage Fender but then the middle strings were far too loud. So I had them moved down. When I looked at the pickup I discovered the poles were longer and I wondered if the mass would impact or not. Thanks again for the detailed answer 🙂

Edited April 12, 2023 by sirmuppet

[Andyjr1515]

3 hours ago, sirmuppet said:

Sorry man but you answer you posted while I did was perfect. 

 

The reason I was asking is I had a set of pickups custom made. We had the middle poles radiused the same as a 7.25 vintage Fender but then the middle strings were far too loud. So I had them moved down. When I looked at the pickup I discovered the poles were longer and I wondered if the mass would impact or not. Thanks again for the detailed answer 🙂

Excellent stuff.  Yes - moving those poles down will lower the volumes for it to balance nicely