Formula350

iTrader: (3)

I know they're in high quality stuff like microphones, professional loudspeakers and in-ear headphones. BUT, are they in any car audio speakers? Generally it's the higher quality the voice coil, the larger the magnet can be to throw everything around. So why not go with a smaller more powerful magnet like the Neodymium kind?

Silly Q I know, not really even car related, but figured someone around here might know

Snootch

iTrader: (3)

Several manufacturers have used neo magnets in their designs. The one series of current speakers that I can think of are Crystal modile sound's soundstage line: http://www.crystalmobilesound.com/Soundstage.htm
I know Alpine used to incorporate the technology in their DDDrive line of coaxials/components, and so did Aura (most notably with their subwoofers. I'm sure there are several other manufacturers currently making speakers using these magnets as well. The examples above are the ones off the top of my head. The main reason Neodyminium magnets are not widely used are mainly the added cost, and the difficulty creating large magnets. Large magnets must be made of lots of smaller pieces epoxied together, since large neodyminium magnets are brittle.

Formula350

iTrader: (3)

That makes sense, I just figured maybe since they're more powerful, they wouldn't need such big magnets

Now for the REALLY stupid question: Can you add a NIB magnet to the back of your speaker for more power? LOL Say, the one I took out of one of my dead hard-drives

Snootch

iTrader: (3)

No, the speaker's motor assembly is designed for the specific magnet that it was built with. The magnetic force focused into the voice coil by the magnet assembly merely controls cone movement, a larger magnet will do nothing to increase the throw of the speaker due to the design of the magnetic gap. Bigger subwoofers have bigger magnets because their voice coils are larger and their magnetic gaps are wider. Here's some reading material about speaker assemblies and how they work:
http://www.bcae1.com/speaker.htm