Redesigning the wheel [speaker magnet question]

[petemoore]

  Difficult to find 'original wheel' information [ie speaker/driver building info].
   Initial results using strong, small magnets and coils indicates to me that unless I'm missing something, making a ''working'' speaker isn't all that tricky.
  I didn't notice that the north and south poles in one diagram were 'inside/outside' of the magnet slot.
   The speakers I've made have the magnet inside the coil only, N/S poles along the coil-line.
     C  o  i  l
     N Mag S
     C  o  i  l 
   While this works quite well, It seems counter intuitive that the poles, according to the diagram with N being the polepiece and S being the surround...how north south on the coil could be pulled N/S when the magnet is "West/East" so to speak.
   Just wondering how the magnetization of pole/surround magnets get the direction 'installed', how much am I missing by using round magnets as pole with North being ''toward the diaphram'' and South being 'toward the back'.

[PRR]

[Mike Burgundy]

PRR's drawing says a lot. Also, for a good speaker you want the magnetic field to be as uniform as possible (density and direction)  across the coil's entire travel. If not, this will result in non-linear distortion (hey, might actually be cool if you're not going for hifi)
Highly recommended: Vance Dickason's books on speaker design. Lots of info and background, focusing on enclosures but also goes into the design of an actual driver. Should be available at a well-stocked library.

[petemoore]

   I'll probably just fiddle around with it some more. 
  Mostly tone is what the ideas are about, probably easier to just buy drivers, but perhaps I'll continue messing with coils/magnet assemblages [ie small magnets make the mag-field structure.
   I likes my speaker/cabinet choices and intend to keep using them.
  I'm not sure I'll be able to make anything worth haulin' around or even plugging in, I have ideas but testing them would be easier with a lab/shop.   

[petemoore]

 Of course the field will be 'better' [stronger at least] when surrounding the other field as shown in the 'good' pic.
  I wish I could find the page again now, it shows "N" in the center-pole, and "S" [on both sides of a cutaway magnet/coil structure diagram] SNS instead of
  N
  S
  ...as the 'good' pic shows.
  Doesn't seem as directly understandable as to how that'd work, and so to just have a devils advocate pose the question:
  Is it feasable to have the mag-poles radial instead of up/down, and what'd be the most common mag-pole orientation.
  I guess the 'good' picture shows it.
  I've never known or seen a magnet with North in the center of a magnetic rod, or that it was even possible.
  So it seemed to me to be one of the following: a misprint or alternative design.
  The pic I can't find now showed East/West fixed magnet orientation to the N/S coil. The pole being "N" and the surround ring being "S".
  Speaker designs seem to segue from basic-est possible drawing from 4th grade science book, to sketchy patent texts of long-scatter-train-descriptions about missing diagrams.

[Mike Burgundy]

What you're describing is exactly what's in the "good" pic - a Ntop Sbottom magnet, with a metal (iron) structure which *channels* the magnetic flux so the S-pole is "directed" straight through the ring surrounding the N-pole of the magnet and the coil. This, if you look at an arbitrary cross-cut through the heart of the speaker, leaves a S-N-S configuration like you mention.
Ferrous metals can channel magnetic flux quite well. The design, size and shape of that specific structure and the ring (bevelled edges or not, etc) have a pretty large influence on speaker behaviour.