simple P-90 Question?

[marku52]

Mike says "There is an effect such as you say, but it involves as well the flux going back up, which points in the opposite direction."

This is what I am thinking of, that the flux lines that are part of small loops close to the magnet that go both up and down inside the perimeter of the outer turns, but penetrate the inner turns, might contribute to a tall coil seeming "brighter". It should have more output as well, if there is anything to this idea.

I'm thinking of looking at a flux plot, as you suggest. And perhaps an experiment using a single strat magnet that I can put in two different small bobbins to test this idea.

[Possum]

Vintage humbuckers are the same height as P90's and some are even shorter, modern ones are only a bit taller. Now to fit a decent amount of wire in a humbucker cavity on a single bobbin, to get something like 8K worth of 42 wire you have to make a very tall coil. The reason tall coils are brighter is because there are less windings on top of eachother than a shorter coil of the same amount of wire, so you have less capacitance, and less inductance because all the copper in the wire has less amount of copper on top the coil within itself. So, in general tall coils ARE brighter, if you're talking same gauge wire and general amount of windings. Easily measured on LCR meter or something like the Sycomp.

As far as magnetic return circuit and tall coils, or short coils, the classic way to warm up a single coil is to make the return further away, so thats why in Rickenbacker pickups and some other classic vintage designs, the coil is short but the poles go way out the bottom of the coil to get rid of some other extreme brightness in alnico pole or bar magne pole pickups. Its also one reason a humbucker's screw pole coil is darker than the slug coil, because the magnetic return is a long path vs. the very short path of the slug pole side. You can warm a bucker up by using two screw pole coils.