An update on what's going on with our subwoofers

[An-i-no 86]

Pictures?

[kirill007 52]

Why did you choose a 4inch coil over a 3 inch coil?

[Quentin Jarrell 671]

The overhung is well just an overhung motor. I'm still waiting on custom tooled 6 inch dustcaps.

I guess I could post fea model pics of the mmag motor if it would be of interest.

[Quentin Jarrell 671]

Both the subs use a 3 inch. I am no longer using Dan Wiggins technology, opted to go with Patrick Turnmire and Enrique Stiles' MMAG technology. Both who are regarded as two of the best engineers in the industry. Who in turn are also partners with Vance Dickason so in the future if I ever decide to build a nice little pair of components I will have avaliable to help with the crossover networks and such. All in all I have much more tool and experience by using these designers.

[Impious 1,476]

I've got a normal overhung driver. Around 17.5 BL with 1.7 re coil, 22mm xmax that should be avaliable mid September and will be selling between 275 and 315 dependent on size 10-18

What would make this driver a better option than comparable displacement drivers that are less expensive? For example, Fi SSD or even an Alpine Type R.

The first MMAG should be avaliable for Xmas. Very large motor with two coil options.

The first a copper daily coil giving the sub a bl of 23.5 and a motor force factor of about 325.

The second option is a pure aluminum coil for spl burps. Our modeling indecates a BL of 69 and a motor force factor of around 2,800. No that's not a typo I said BL of 69 and force factor of 2,800 for those who think they need a retarded amount of motor force.

I have not yet received a sample yet on the MMAG so that info is purely based off several FEA programs which are normally pretty accurate.

That is going to be a beast of a subwoofer. The MMAG motor allow you the ability to increase the motor force here?

Any plans to implement MMAG into a more SQ oriented driver in the future?

FWIW, I'd be interested in seeing the model pics of the motor

[Quentin Jarrell 671]

The overhung is actually more inline with a FI BL. The BL rating I posted is on a dual one ohm coil with an Re of 1.7. So motor force is around 195 ish. And the xmax is overhung coil length. The actual 70% BL figure will be around 28-30. But I'll wait for Klippel results to post those.

I'll post pics of the mmag FEA once I get to the hotel and you'll see the advantages of the mmag

[Impious 1,476]

The overhung is actually more inline with a FI BL. The BL rating I posted is on a dual one ohm coil with an Re of 1.7. So motor force is around 195 ish. And the xmax is overhung coil length. The actual 70% BL figure will be around 28-30. But I'll wait for Klippel results to post those.

Makes sense

I presume based on the motor force the overhung driver is going to be a low Q ported enclosure oriented driver?

[Quentin Jarrell 671]

Although I am using a fairly heavy moving mass. Yes the overhung will be a no frills affordable daily beater for the youngens. Pretty much the same as others but running 50-100 bucks cheaper being they will only be sold direct thru me. The mmag once I have OSSD (oversized sd) baskets built next year, akind to the critical mass basket body and edge will be dealer direct.

[Quentin Jarrell 671]

What you are looking at here is a 260mm bottom plate, 50mm thich 270mm OD magnets, then 260mm top plate, magnet, top plate.

The top top plate and magnet is smaller because flux from the bottom magnet also flows through the botom top plate directly into the top top plate.

Both top plates and top magnet is 25mm thick.

Now, the 50mm tall coil sits directly in the middle of the two plates. So as it moves up or down is loses flux from one plate but gains flux from the other. Ideally you want the flux path equal on both plates so BL remains constant. So, the coil see the same amount of flux until the bottom of the coil meets the bottom of the very top, top plate. This means the BL remains 100% (ideally) constant until for 37.5mm ONE WAY.

I am also using a very large gap in order to get the spl coil to fit. 1.25mm between the pole and coil, and 3mm between the coil and top plates. Even with this large gap I'm getting motor forces exceeding other overhung drivers do to the ability to concentrate flux.

In order to get the same xmax on an overhung driver you would need a single top plate of around 50mm thick and a coil 125mm long and you would need a xmech of 90-100 to make sure the coil doesn't slap the back plate.

[Quentin Jarrell 671]

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.

[Impious 1,476]

My ability to interpret FEA modeling is admittedly elementary. But, based on the thickness of the top plates & top magnet, the SPL coil version only has 10mm one-way of coil overhang and, if I'm understanding the basic representation of the FEA model correctly, due to the concentration of flux the fringe field doesn't extend much beyond the coil itself. How is it able to achieve 70% BL @ 25mm when it appears it will begin loosing BL comparatively rapidly as soon as the coil travels ~10mm?

Not busting your balls. Trying to improve my understanding.

[Quentin Jarrell 671]

That's correct, the coil will retain 100 percent flux for 10mm one way. then as is leaves the bottom plate (as the coil moves out) it loses flux. Once the coil moves from 10mm to roughly 25mm. there is roughly 70 percent of the coil length(L) saturated than at rest.

On a side note, I don't pretend to know everything either nor will I intentially throw out a bunch of bullshit. This is the reason I have enlisted the help that I have, to ensure everything that I am invisioning is either executed correctly or changed due to my flawed thinking.

Edited June 15, 2012 by Audibel Customs

[edouble101 314]

I like the way this is going. No BS

[deeper1 0]

Another south Louisiana basshead waiting for some homegrown products here !

[Quentin Jarrell 671]

Klippel analyzing has been completed. Just waiting for the synopsis.

[Julian 641]

How is red rock acoustics? N3.....

Edited September 29, 2012 by Julian

[Quentin Jarrell 671]

How is red rock acoustics? N3.....

Do you mean how is the quality of their design consulting? If so then, Patrick Red Rock's CEO, was personally recommended by Dr. Wolfgang Klippel (by email) to be the best qualified person in the industry to measure transducers and also had the newest set of toys from Klippel.

Vance Dickason uses his FEA program SpeaD in his cookbook in the first chapters on transducer design and I quote Vance on page 13 of the 7th edition of the cookbook. "all the data and graphs (and some of the text) used for this tutorial were provided by Red Rock Acoustics and specifically by Red Rock's CEO, Pat Tirnmire, who happens to be one of those "hard to find" transducer designers.

I would think it's hard to get that kind of recognition from Klippel and Dickason if you dont have a firm grasp on design. Plus the guy is top notch. He takes the time to help the little guy "me" when he normally deals with people like Sonovox who has a minimum on 1,000 units per driver order.

[rowdyful7 10]

anything new?

[Quentin Jarrell 671]

[yautja 0]

Here's a few FEA graphs

A cut a way of the motor

 

I've read in your other posts that you use SpeaD and Reverse SpeaD to design your motors. Do you happen to use DYNE Analytics MoTIV as well? Only reason I ask is because the picture above is exactly the way it's shown in MoTIV. I've never seen a video of someone using SpeaD so I'm not sure what their graphs or models look like.

 

Thanks

Edited February 18, 2013 by yautja