Speaker magnets

There are magnets and then there are magnets.  The older speakers either used Ferrite or Alnico magnets.  The alnico magnets were used in some of the better speakers at the time, like JBL.

From what i understand the size is not necessarily the thing that make it better. For example High Q driver used in Open baffle designs can have small magnets but smaller gaps in the voice coil (closer tolerances from what i understand are part of what makes a higher efficiency driver hi efficiency).
 Magnets got really big in the desire for big bass from small drivers to get the control of the cone and maximize excursion (why small speakers usually need lots of power and damping). Large drivers may not need the excursion so the magnets may be smaller. so magnet size is not a factor in sound quality from my experience, its all in the overall design and intended use. 

Maybe a speaker designer will chime in and clear some of this up. 

Thanks guys,  there is plenty of info here to get me started in the right direction.  Looks like I have a bit of reading, accompanied by a fair bit of trial and error, good job I have plenty of free time :^)

There is always a trade off.  The magnet needs to match the designers goals.  Large magnets do increase efficiency.  They also roll off and limit low frequency extension (all other variables being equal).

Most modern speakers do not have anywhere near the size magnet or magnet strength of a good vintage speaker at all, nor anywhere near the voice coil size and type and amount of wire around the coil, which gives the vintage type driver a tremendous advantage in efficiency and control over cone motion. They use a type of magnet that does not deteriorate over time as well as a fiber surround that does not deteriorate either. I have 70+ year old vintage models that work and sound like they were made yesterday because of these reasons.