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I saw one of these listed on a website and the specs are incredible.

has anyone seen these before?

*Electrical Q Value -Qes: 0.68
*Mechanical Q Value -Qms: 2.82
*Total Speaker Q Value -Qts: 0.55
*Free Air Resonance -Fs: 15.60 Hz
*Equivalent Compliance -Vas: 482.0 liters
*One-Way, Linear Excursion -Xmax: 54 mm :dizzy:
*Efficiency -SPL 1W/1m: 86.20 dB SPL
*Effective Piston Area -Sd: 1210 cm^2
*DC Resistance -Re: 4.2 ohm
*Nominal Impedance -Znom: Dual 2 ohm
*Thermal Power Handling -Pe: 2000 W
*Force Factor -Bl: 18.16

Apparently it weighs around 100 lbs or so. I had a friend who used a pair of Digital Design 18's in his home theater and they were nuts but the specs on this seems even more insane.
 

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Seen them, handled them, taken them apart, had them re-coned, heard them, used them to work out with:flex:...
 

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I seem to recall designing that boat anchor ;)
Wish that our vendor could have come through with the NdFeB that we had asked for... months of "we will be able to make it soon" and "sure we can make it... oh wait, it needs to be XXXmm in OD" lead me to simply using lots of ferrite to get the job done. Does some things well, but I feel it truly missed the mark with that motor strapped to the back of it.
 

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Scott,

I'd be really interested in any insight that you have on these drivers. In particular I wonder how you feel that it "missed the mark"? IMO the cone, suspension, frame and softparts are really good providing plenty of linearity and throw for almost any possible scenario, but still putting the brakes on in just the right spot too to prevent the driver from damaging itself. Did using the ferrite motor result in an overall loss of motor force? That's one thing that I would've liked is more BL for smaller boxes, higher sensitivity. Lower inductance and less weight is always nice too. What other differences would the neo motor have made?

One other question. Did you do the MX series too? It has a neo motor, but appears to be overhung 4"vc? The frame, cone and surround look similar.
 

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When I look at a ground up design, I take all things into account. This one was originally designed to be a Neo motor, and I had designed the basket and original motor around this, with the MX in mind to use the same basket, but with a backing plate and the motor attached to that (which still went fine). But, when we had several issues and massive delays with the magnet manufacturers, I slowly saw what I had originally designed things to be slip away and doubling in weight. For a flagship driver, I wanted something that really looked and performed the part... and with that much motor hanging off the back it missed the mark.
It also seems that the first couple of batches were the only ones that had the inductance rings in them. Of the couple we have had in recently to recone and "upgrade" for other applications none of them seemed to have the shorting rings or pole cap. Im sure the inductance has gone through the roof with that as well (or maybe I got two random versions that they forgot to put them on...).

The soft parts in general work in harmony with the motor/coil, but again, we ran into several tooling issues with the original surround and again had to go back to a half roll just to get the sub to market. I have the other surround profiles that would have made the MK2 version of the driver done, but no desire to push them into production at this time (they are XXX basket specific designs). In general it just wasnt exactly what it should have been... but since I have moved on its up to the new owners to push things further if they want to.

Thanks,
Scott
 

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Wait you guys can recone these things? How does that change things with the driver? I can't say whether the shorting rings are present or not on mine, but the aluminum cap on the back of the motor is there on the 2 I've taken apart. The inductance is causing a roll off in the upper bass and a test with a WT3 gives LE figures between 3.5 and 4.0 on the drivers I've got though. Not exactly low.

Were you trying for a high roll surround? All of that makes me wish that it had been what you intended it to be in the first place.
 

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Yes, we had a couple of different high roll profiles with strain relief in them. We had issues with the first tooling company then with the second company for materials choice. Just couldnt quite get it right.
The aluminum plate on the back of the motor is purely cosmetic on the XXX. It does hold the motor in place on the MX. There should have been a bolted on aluminum pole cap on the pole piece of the XXX, and less noticeable would have been the rings on the inside of the motor. From the LE of 3.5 to 4.0 I would have to assume that they arent in there.
 

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I didn't mean the aluminum back plate. :T. This guy with the bolt into the pole piece...






I think that the aluminum shorting ring was in there towards the top but it was very hard to see down in there.






You said that you saw some later motors without that aluminum cap in place? Here is a close mic FR of a sealed driver in 10cu ft. Does that look about right? I'm just assuming that these dudes were never going to be mistaken for midbasses regardless of how good the inductance was due to sheer mass and size of the moving parts.



 
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