High Alnico II pickup vs low Alnico IV

SunDevil

So I believe that the magnet strength and the amount of coil material determine the pickup’s output, but it’s also true that the strength of the (inductance?) field decreases the further away from the magnet.

This seems to be backed up by the increased proportion of bottom end you get from raising a pickup closer to the string - more power / output allowing better low frequency transfer

If I’m correct, then for the same pickup wind, it should be possible to achieve the same inductance field strength with a Alnico IV magnet pup as you get from an Alnico II pickup - you just need the Al IV further from the strings?

Ergo, you can get them to sound the same with different pickup heights

Whaddya reckon?

Alegree

Try it. You'll quickly notice that's not the case.

You can't get the same combination of distance from the string and string magnetism at any one time, both of which play an integral part in the tone.

SunDevil

Thanks @Alegree

Assuming the field strength decreases by 1/R, I guess there’s less variation in that field strength over a certain string vibration frequency for a stronger magnet - is that the difference?

Alegree

I believe it's a inverse square relationship of distance (but don't hold me to it).
So you'll notice the same amount of change regardless of magnetic strength in theory.

Alegree

To clarify my previous point - same amount of change in terms of a percentage of the original.

robgilmo

I liked this subject better when I thought pickups were magical things that us mortals could never understand.

Modulus_Amps

so you are saying you don't think the type of magnet material affects the tone and that is is purely a function of inductance field strength? I do think there is some magical things that go on beyond field strength.

SunDevil

I think (..always dangerous!) that it’s th magnetic / inductance properties of the pickup that matter.

The physical makeup of the magnet only determines its ability to hold and retain a charge?

So,  in theory I believe you can degauss an Al IV to the maximum gauss of a Al II and IF I understand @Alegree correctly, the magnetic strength decreases with distance in a reverse exponential curve and so 2 magnets of different strengths would have different curve angles with distance from the magnet, if you were to draw them on the same graph.

So a lower pickup height with Al IV will give a different flavour from a higher set Al II, because those curves dictate a different inductance change over the travel of the string vibration and you’d get them closer by degaussing the Al IV to Al II levels??

Roland

This is the point where some one with a spreadsheet draws a nice graph showing not only the reduction of magnetic field with string height, but also the variation over the distance which the string vibrates. 

Danielsguitars

just buy different magnets, problem solved