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Quentin Jarrell

High Excursion Shallow Mount Neo

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shallowmountneoflux_zps53e8fa26.jpg

 

 

Spent a little time today on a possible 10" and 12" driver for the folks with limited mounting depth.  Any possibility of building this driver will depend on the cost of manufacturing.  It would use a 8 layer alluminum coil.  Be around 600 watts rms.  And has motor breaking on both the outward and inward stroke.  By looking at the model you can see the motor does not have any outter assembly.  No outside top plate  or magnets.  It uses the flux path of the inner neo magnets alone to create the flux gap that the coils rides in.  This use of the magnets also creates the motor breaking.  This allows me to put the entire motor inside the basket and attach the spider to the bottom of the coil.  Xmax on this sub should be ~23mm one way.  Mounting depth is limited to a 12 spoke 10'' and 12'' frame plus about 5mm. 

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shallowmountneomagneticfield_zpsa19e72a7

 

Above is the magnetic field that the coil travels through.  At  around 27mm of travel each way the ends of the coil hits a point (zero on the graph) where the flux field reverses and this magnetic reversal continues to increase to become the equilvilant opposite of the original BL.  This is effectively a motor break that is as strong as the drivers motor force. 

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This is cool. There are few quality shallow mount drivers available in the market. The few that are out there sell out almost immediately. Tuned in.

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Seems very similar in concept to Mowry's Steallus....let the coil ride in the magnetic field of the magnets themselves with no "gap", though I don't know if he implemented the "active" breaking concept.  What happens as the coil moves....is it going to "pull" the flux with it since there's no gap?

 

Either way, great idea.  I had mentioned before that shallow mount higher excursion, linear BL designs are a hot commodity right now....the SI BM's seem to sell out quickly and since they aren't in production sell used for more than they went for new.  All I ask is you keep parameters in-line with something that performs well IB in a vehicle, and that you hopefully make a 15" driver smile.png

 

Any chance the 10" would play enough to function as a midbass?  Or an 8" implementation?

 

4214d1203888966-steallus-as123001.jpg4215d1203890518-steallus-as073001.jpg

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Interesting. I had the chance to hear a pair of the shallow mount SI  neo motored subs. The system as a whole sounded great and sub output was impressive for a pair of 12s in a 1 cuft box. It was all in a little Volvo hatchback with 1K watts of power on tap for the subs. If I had to guess that system could easily break the 140s on the TL. Quentin if your subs can best the SI subs I'm be in for at least a pair, cost permissible. :)

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My comment is to make these IB friendly. Shallow mount IB will free up even more trunk space. This would also open the door to SUV installs for IB much easier. 

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My comment is to make these IB friendly. Shallow mount IB will free up even more trunk space. 

Exactly.  Hang them under the rear deck & it'll take up virtually no trunk space.

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 Because of it's strength Neo's flux naturally wants to turn back onto itself.  It is actually less reluctant for neo to jump back through the air rather than traveling through a back plate then pole then top plate like in a traditional motor.  This is why the typical way neo is used by a number of so called extremely strong Neo motors is extremely lossy.  If you look at other designs like the Critical Mass UL or the B-Hive that Thilo Stomplers uses they have the capability to be just as strong if not stronger using much much less Neo.

 

 

The below pic will better help understand the gap that the coil travels through.  In the center you can see the flux field is pointed out showed by the arrow.  They then turn back into the top and bottom portion of the motor in the opposite direction, again showed by the arrows, creating the motor breaking. 

 

fluxmagnetudetogether_zps5930cac9.jpg

 

 

 

I'm not a IB guy and honestly don't know much about it, however a 12 inch model could look like this.

 

Re 2.05

Fo  29.7

qts .7

qes .778

qms 7

vas 60 liters

bl   8.9

xmax 25mm

spl 84.97 @ 1w

 

 

That should result in an F3 @ 30 hertz with a Qtc of .7  Again I don't know much about IB but I could easily change parameters to meet the needs of the customer.

 

I'd assume with nearly twice the xmax of the SI (although this sub would be deeper, limited by basket depth) It should produce pretty decent output.

Edited by Quentin Jarrell

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Most common routes for IB in a vehicle (that require minimal EQ) are high Q/High Fs like you have modeled there, and lower-mid Q/Low Fs....which is my preference, personally.  Q in the .35-.4 range, Fs around 20hz.  With the low Q you can shove several of them in your trunk without having to worry about Qtc raising to an unacceptably high level once you start putting things in your trunk that take up room or simply due to the ratio of Vas to Vb if you have several drivers with a large Vas. 

 

The other good thing about low Q/Low Fs is they generally make good small sealed enclosure subwoofers....which works well with the shallow depth theme for those who don't want to run IB, another great sales feature wink.png

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makes sense didnt think of the junk in the trunk

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Any chances of an 8 inch?

not for this motor.  It's too tall about ,4.75 inches, to be a reasonable shallow driver.  There are less expensive routes to go for 8''s

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Most common routes for IB in a vehicle (that require minimal EQ) are high Q/High Fs like you have modeled there, and lower-mid Q/Low Fs....which is my preference, personally.  Q in the .35-.4 range, Fs around 20hz.  With the low Q you can shove several of them in your trunk without having to worry about Qtc raising to an unacceptably high level once you start putting things in your trunk that take up room or simply due to the ratio of Vas to Vb if you have several drivers with a large Vas. 

 

The other good thing about low Q/Low Fs is they generally make good small sealed enclosure subwoofers....which works well with the shallow depth theme for those who don't want to run IB, another great sales feature wink.png

AGREED!  Yes I am yelling.  This is an untapped market IMO and a guaranteed money maker.  I'm very excited at seeing you looking into this prospect.  Even at a "modest" excursion level like the BMs (which IIRC were the longest throw shallow drivers on the market), these are worth their weight in gold.

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I spent the last 12 hours or so tweaking the current motor to get the most stoke as possible while retaining enough motor force for the moving mass.  I want to stay at 120 mm in total length this will keep the motor under the working depth of a 12inch 12 spoked basket with a traditional cone/surround.

 

shallowmountneo31mmxmaxjpeg_zpsc0970433.

shallowmountneo31mmxmaxjpeg2_zps0dddd1b7

 

 

in the above pics the colors are:

 

copper is the coil

middle silver is the gap plate

dark gray is Neo magnet

outside silver are top and bottom plates

 

Imagine this sitting inside a basket just as a pole piece would.  In this case the pole piece is the entire motor.  No other surrounding magnets or plates are required except for a thin aluminum plate which will attach the motor to the frame.

 

calculating the B field which is a total of ~70mm we can expect a xmax per 70% BL at ~30.6 mm one way.

 

A 12inch basket using this motor, this driver should work in 5.25 inches of total depth (not including enclosure rear material thickness).  Meaning the cone should not hit as long as you have 5.25 inches of clearance between the inside of the bottom of your box and the bottom of a rear truck seat.

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You are working on some very cool stuff man! I'm tuned in for sure.

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Double post


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How could you incorporate a shorting ring into this design?

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How could you incorporate a shorting ring into this design?

 

Don't need to.  The coil is tiny in comparision to ordinary subs.  22mm versus 60-70 mm on subs with similar xmax. And the coil is not encased in steel as in traditional motors.

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It's also always iron core instead of air/iron like a standard overhung, so I'd expect Le(X) to be pretty flat.

 

I'm still curious if the flux field is going to be more highly modulated by the movement of the coil since there isn't a gap, which is something shorting rings in a standard motor can help.

 

My 2nd question is how you intend to attach this to the basket?  Are you planning to mount this "in" the basket like the Dayton's

 

It's unfortunate this project is probably pretty far away from product hitting the street.....I'd really like to try some of these out :D

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The gap should not fluctuate anymore than a standard design does. The two neo magnets in the pics above and below the "gap plate" are magnetized at 90 degrees from the "gap plate". This should keep any modulation to a minimum.

Faraday rings do help when used properly. But they can make a motor nonlinear as well. for example when a large pole cap is used without any use of rings in the motor.

For cost and R&D purposes there will be a 5mm thick aluminum plate bolted to the bottom of the basket. The motor will then be epoxied onto this plate and secured with a center bolt into the bottom plate of the motor. The spider and body/edge will be fastened to the basket as normal. The coil and former will be inverted so as the coil will be above the body with little clearance as possible.

The coil is large enough for the expected Pmax I don't foresee any thermal issues from the coil not being force cooled like normal.

After a few production runs if there is enough demand I will have custom bodies built to transfer the coil under the body. However I would still expect it to remain without a dust cap due to the xmax. I like to keep the xmech 60% more than the xmax to prevent hard bottoming out. So if I went with a fully capped body it would add ~2" to the overall height to insure the cap didn't strike the top of the motor.

As long as the manufacturing cost is reasonable it is possible to have a production run in 6-7 months as long as the factory doesn't drag their feet on the sample.

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So this is similar to the Lanzar Neo subs and Illusion drivers mounting wise?

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So this is similar to the Lanzar Neo subs and Illusion drivers mounting wise?

Exactly. Just no outside motor structure around the coil.

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Didn't know the SI shallows are done. I was intending to get them later down the road when my build starts, but I guess not. lol. I am looking to do a floor box in the cargo of the suv and these would be badass with only 5.25" depth. Does that include xmech depth?

 

If price is not over the top, I'd definitely love to have these.

 

subbed. 

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That is total working room with cone in its out most position. Not including box bottom thickness.

Remove the motor from a standard 12 sub with a 12 spoke basket and that's what you will be working with.

Edited by Quentin Jarrell

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