Tc Sounds To The Rescue!

I hope it's okay to post these pics up....
If there's anything wrong with it, just take it down....

 

After figure 12 that starts to get really scary really quickly....wow.

 

I don't want to come across too cocky, but I thought I'd share my satisfaction at finally being proven correct. I reverse-engineered XBL2 many moons ago using a little detective work and shared the results here.

:detective: Bill

 

Good show bill!!! We had a discussion on it a while ago too (Steven K was involved). My thought was basically a topplate like this:

(i)

with the i representing the coil, compared to your sketch (which for comparison's sake I will do like this [il with i being the coil, and l being the pole)

Ah well, I was kinda close, but you were closer.

 

Seth,

About triple (or more) gaps look at Figure 13. You only need the voice coil to be long enough to span into a pair of adjacent gaps. That's it. The former gets longer (obviously because it needs to penentrate deeper into the motor) but that is relatively little in terms of mass. So you can go to 3, 4, 5, 6, 300 gaps if desired, and it functions the same. And you keep getting more and more stroke.

Flux will balance itself out quite nicely, and while there can be some minor issues, it's really not that tricky for someone who knows what they're doing.

As far as the variable coil thing, the upper "extra layers" don't have to enter the gap. they are essentially pumping up the L portion of BL out near the ends. XBL^2 pumps up the B portion of BL out near the ends. Basically two approaches to the same result, but I know which one I'd rather build...

Bill,

You did pretty much get it - good job! One (or more) voice coils transecting two (or more) gaps is the way to do it. As far as suspension things, we can talk after CES.

Steven,

The cornpup is a trade secret...

Dan Wiggins
Adire Audio

 

Hi Steven,

Thanks, bro!

Looks like an interesting forum...can't believe I only just found it. :huh:

By the way, that cornpup nonsense you turned me on to has worked it's way deep into my lexicon--thanks a ton.


Dan,

You seem to have left out the part about my prize...

Wish I could justify a trip to CES. Maybe when I bring my own brainchildren to market. :?:

Bill

 

Hey, Bill... welcome to this forum!
I can tell you'll be one hell of a powerful member - awesome!

I can't believe how close your guess was to what XBL2 was initially.
I was proud because I figured it was a top plate shaped more like the face of a capital "B" (darn fonts... even sized top and bottom curvature )... but you nailed it much closer than my guess.

In fact, I'm particularly impressed with how you carried it through with a flux and BL curve analysis...

And, I want to tell you from my own experience prototyping up XBL2 drivers for our own product line, that this curve that you generated here:
http://img.villagephotos.com/p/2003-5/1236....1shortcoil.jpg
is exactly what happens when your voice coil is wound too short. B)
Your at rest BL is much lower than it should be, and your efficiency numbers also suffer equally.
I've got DUMAX plots of exactly that.
Well done!

 

Bill, pardon my ignorance... but you said that "modeling up drivers is what you do for fun".. you've got some good tools for it, obviously.
Do you have industry involvement, or is this truly just something you enjoy doing for fun?
Believe me - doesn't matter in the slightest IMO as far as your credibility goes... you've displayed that! I'm just curious as to your involvement, and if it truly is just a hobby.. why is it just a hobby? You seem to be quite passionate about it! B)