I came across this analysis of the two types of magnets and thought it may be of interest to people here:
https://www.gitec-forum-eng.de/wp-content/uploads/2019/03/poteg-11-7-magnets-alnico-vs-ceramic.pdf
https://www.gitec-forum-eng.de/wp-content/uploads/2019/03/poteg-11-7-magnets-alnico-vs-ceramic.pdf
Very nice. Thank you for posting that!
I once worked shoulder-to-shoulder with two speaker design engineers. One of them was an expert at designing the actual speaker driver, the other at designing speaker systems using the drivers his colleague designed.
The first of these two could make a speaker sound quite different simply by changing the glues he used to assemble the cone / coil / spider, or by changing the dust-cap over the voice coil, or by changing the cone material, or by several other means.
You know the one thing he did not care about? The type of material used in the speaker magnet. All he cared about was achieving the right value of the BL constant. It didn't matter whether the "B" came from ceramic, AlNiCo, or horse-feathers.
My background is in science, not speakers. And I agree 100% with the speaker designer. Maxwell's equations of electrodynamics tell you exactly what the speaker voice coil does in a magnetic field. The material used to create the magnetic field is quite irrelevant.
Personally, I have very little doubt that "ceramic" and "AlNiCo" guitar speakers sound different because of the materials used to construct them, and not because of the actual magnetic material.
But just try telling that to experienced guitar players. You might get lynched for it.
-Gnobuddy
I once worked shoulder-to-shoulder with two speaker design engineers. One of them was an expert at designing the actual speaker driver, the other at designing speaker systems using the drivers his colleague designed.
The first of these two could make a speaker sound quite different simply by changing the glues he used to assemble the cone / coil / spider, or by changing the dust-cap over the voice coil, or by changing the cone material, or by several other means.
You know the one thing he did not care about? The type of material used in the speaker magnet. All he cared about was achieving the right value of the BL constant. It didn't matter whether the "B" came from ceramic, AlNiCo, or horse-feathers.
My background is in science, not speakers. And I agree 100% with the speaker designer. Maxwell's equations of electrodynamics tell you exactly what the speaker voice coil does in a magnetic field. The material used to create the magnetic field is quite irrelevant.
Personally, I have very little doubt that "ceramic" and "AlNiCo" guitar speakers sound different because of the materials used to construct them, and not because of the actual magnetic material.
But just try telling that to experienced guitar players. You might get lynched for it.
-Gnobuddy
I wonder if anyone has ever tried this? Make a current source, take the magnet out of the guitar pickups, then put the current through the winding to re-make the missing magnetic field. As there will be some voltage drop across the coil, capacitively couple the pickup to the volume control.
Make it so the pickup magnetic strength is another control, either on the amp or guitar itself. I'm pretty sure, someone will swear by it. They do that in speakers and - whooaa! Field Coil Uh, OK. I always thought field coil speakers were a clever way to kill two birds with one stone - eliminate the need to purchase magnet material and a choke for the power supply -
Make it so the pickup magnetic strength is another control, either on the amp or guitar itself. I'm pretty sure, someone will swear by it. They do that in speakers and - whooaa! Field Coil Uh, OK. I always thought field coil speakers were a clever way to kill two birds with one stone - eliminate the need to purchase magnet material and a choke for the power supply -
I agree, a very clever solution for the time.
Then powerful new permanent magnet materials came along, and semiconductor diodes, and large-value electrolytic capacitors. And the price of copper soared as we humans continued to deplete earth's accessible natural reserves.
After all that, feeding vast amounts of DC power into a large electromagnet filled with expensive copper wire no longer made sense.
I still find the strength of contemporary "supermagnets" quite astonishing. A one-inch cube can generate enough force to crush your finger bones if you let it get out of control, and even a little coin-sized one can give your fingers a good pinch and leave you with blood blisters.
Compare that with the weak steel bar-magnets in my long ago middle-school science cabinets, and the difference is incredible!
More on topic, the giant pickup used in the 1932 Ro-Pat-In electric guitars was that big for a reason - the magnetic materials available at the time were very weak, so you needed a huge magnet!
-Gnobuddy
