In depth paper on Low Reluctance Return Path MMAG motors

[Quentin Jarrell 671]

The below link goes over the advantages of using LRRP and MMAG.

http://stepip.com/IssuedPatents/Low%20Reluctance%20Return%20Path%20Motors.pdf

[Quentin Jarrell 671]

here's another white paper on MMAG

http://stepip.com/PublishedApps/MMAG%20copy.pdf

[stiffler style 9]

Way over my head, but it sure is interesting. Did you write those?

[Quentin Jarrell 671]

Way over my head, but it sure is interesting. Did you write those?

No, the second link is written in more layman's terms

[kirill007 52]

Nice papers, but they look quite outdated.

How old are they?

From 2005?

The technology looks promising, but it looks too good to be true.

Edited October 25, 2012 by kirill007

[Quentin Jarrell 671]

Nowhere near too good too be true. Wouldn't be patented if so. Some prestigious companies like Fishman use the technology.

[Quentin Jarrell 671]

The speaker in the first paper is used in this

http://www.fishman.com/products/view/sa220-solo-performance-system

[Quentin Jarrell 671]

Nice papers, but they look quite outdated.

How old are they?

From 2005?

The technology looks promising, but it looks too good to be true.

Now, here is the same exact motor but with a 95mm long coil. As you can see nearly the entire coil is saturated in flux giving us a BL of 69 and some change with a motor force factor of 2,833. Using tthe 70% bl xmax formula we get a xmax of roughly 25ish with a motor force factor of 1,388 at 25mm one way. This still leaves 15 mm of clearance to the back plate.

This is one version I have already modeled. To my knowledge a motor force factor of 2,833 is a bit higher than most on the market.

[kirill007 52]

But what is the use of such high BL?

Fi has dropped BL on a few woofers, because it caused a few problems.

What would be the target group of such drivers? small PA systems?

[Quentin Jarrell 671]

No problems with high BL in SPL applications. In fact more the better. The faster you can accelerate the moving mass the louder the sub will be.

[REVpuggie 23]

As far as I can see this is a split-gap design so this is nothing really new .... who would have thought : a buckingmagnet between the gaps ... really innovative

[Quentin Jarrell 671]

As far as I can see this is a split-gap design so this is nothing really new .... who would have thought : a buckingmagnet between the gaps ... really innovative

Read the second one if you didn't understand the first. It reads a bit easier so you might see a bit better. No, it's not NEW, the patent was given to it years ago.

[Quentin Jarrell 671]

Going a bit further into the technology helps in high xmax which becomes not practical with overhung.

Say I want 62.5 mm of one way excursion. I use three top plates 25mm thick sandwiched with two magnets 25mm thick while using a coil 50mm long.

In order to get 62.5 mm one way xmax with over hung you would need one 25mm topplate and a coil 150mm long. That's almost six inches. A 4 layer copper coil this long would weigh upwards of 2 pounds. It would take a rediculous amount of motor force to compensate for it. Not to mention a coil that large is very very expensive.