Peerless motor calculations updated

[capslock]

I have taken up a loose end that had been gathering mold:

http://www.diyaudio.com/forums/showthread.php?s=&postid=1068192#post1068192

Basic story:
The Peerless CSC line used a pretty simple magnetic design that yields an asymmetric B curve. However, they also employed an unconventional winding technique that uses asymmetrically shorter voice coil windings. As the current HDS drivers still use the essentially the same motor design, I wondered why they had given up on the asymmetrical winding technique.

I redid the simulations in FEMM to make sure I can obtain only the normal component of the B field, then I exported the curve to Excel and did a numerical integration for each layer of the VC.

The answer is that the asymmetry of the VC helps to compensate the asymmetry of the motor, but while the result may look more pleasing to the eye, it actually sacrifices the reasonably flat plateau that can be obtained with a conventional VC.

[Paul W]

Hi Eric,
I apologize for going a little OT, but do you have an opinion of the Active Impedance Control used by Eighteen Sound in drivers like the 10NDA520?
Thanks,
Paul

[capslock]

Yes I do: if done right, it'll solve the problem of flux modulation for good, and be as effective as copper shielding concerning Le nonlinearity.

It'll deal with flux modulation at low frequency where a copper ring is no longer effective. It won't deal with a poor iron design (static Bxl curve), though. Neither will it deal with spider and cone induced errors.

[cotdt]

since the HDS uses the same motor as the CSC but doesn't have the assymetical voice coil winding, does that make them inferior?

[augerpro]

Concerning the new HDS motor, can you explain for us laymen how this affects the performance versus a conventional design?

[Paul W]

Neither will it deal with spider and cone induced errors.

Are you hinting that this driver has spider and cone problems? I've not been able to find any measurements of it except the factory curves. Can you share any info or point me to any links?
Thanks,
Paul

[AJINFLA]

Eric,

have you seen TC's motor design that Dan Wiggins mentioned http://www.tcsounds.com/lms.htm used by eclipse http://www.eclipse-web.com/sw8000/linear.html in some of their subwoofers?
Here is a some data for one: http://www.diymobileaudio.com/forum/...54&postcount=1

cheers,

AJ

[capslock]

since the HDS uses the same motor as the CSC but doesn't have the assymetical voice coil winding, does that make them inferior?

Not at all. Blow up the green curve to the amplitude of the red curve. It's far superior.

[capslock]

Are you hinting that this driver has spider and cone problems? I've not been able to find any measurements of it except the factory curves. Can you share any info or point me to any links?
Thanks,
Paul

No, but those are the weak spots in any driver once the motor has been cleaned up.