Monday, March 22, 2010


I finally have some hard flux measurements on a filed coil project we have been working on.  The request was for a field coil version of an existing commercial driver and the first step in the process was to tear apart an existing unit to get the needed measurements for an apples to apples comparison.  Somehow I get great pleasure from tearing things apart to see how they work.  You never know what surprises you might find.
 I just love that wire and as you can see the cone has been removed from this driver to allow me access to the gap.  The big surprise came when I would place the cone on a flat surface and how it acted like a suction cup and would not let go.  The surround is so soft and pliable that it creates such a suction that it must be slid of the edge to remove it.  It will slide freely across a flat surface but the minute you try to pull upward it grabs on and will not let go.  I actually put this to good use when I had to replace the hard drive in my imac.  The plexi screen protector is held in place with magnets and to remove it you are instructed to use rubber suction cups to pull.  Having the Alpair 10 basket handy a quick pull liberated the plex and I was free to proceed with the drive replacement.  I know the verbal account doesn't really illustrate how cool this "basket as suction cup" really is so here is a picture to show my faith in the strength of the bond.

Enough with the destruction and onto some production. I guess this means that the cat is officially out of the bag so it is safe to say we are working with Mark Fenlon to come up with an affordable field coil.  The projected debut of the prototype driver will be at the Lone Star Audio Fest in a few weeks. 

At the fear of becoming overly technical, I will close with the plots of  the gap flux density of the motor in question both measured and simmed.  The target flux is about 1.3T  and things are looking good.  


  1. Go guys, go!

    Will the efficiency go up? Let me know when I can order a pair for the Azurahorns --


  2. A funny aside. It seems that our humble blog is banned form Mainland China. I guess that means their Junk can get out, but our junk isn't getting in.



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