alnico or ceramic?

I currently own a vibrochamp and 2 champs. I replaced the vibrochamp and one of the champs with jensen c8r speakers. (I wanted to preserve the original speakers). My last acquisition, last week, came with a destroyed speaker so I put one of the originals from the other 2 in it and I can't believe how much better it sounds than the other 2!! One of the originals has a flat round magnet which I am assuming is ceramic and the other has the smaller, almost cylindrical magnet with a u shaped bracket behind it. Is this one an alnico magnet and if so is this the reason my latest sounds so much more tonefull?

You're correct in identifying the magnet types. There are a lot of factors that affect a speker's tone, but the main difference between the ceramic and alnico speaker magnets is that alnico causes compression as the voice coil field intensifies, while ceramic magnets do not.

The result is loosely analogous to the difference in the distortion characteristics of tubes and transistors.