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-   -   Neodymium Experiment (http://www.diyaudio.com/forums/markaudio/222764-neodymium-experiment.html)

markaudio 3rd November 2012 01:45 AM

Neodymium Experiment
 
2 Attachment(s)
Hi Guys,
Here's an Neodymium Motor Set experiment produced by Evan Yu on an Alpair 6P driver. The design is a modified U Yoke type. The housing has been CNC'd to trial run on the rear of the 6P's frame, being bonded into position. Its an early experiment for this driver using Neo.

Apologies for the small graphs and dark photos. Very busy right now so don't have the time to make high-res.

I did snatch a quick 10 mins of listening time on this driver last week. I was impressed. Very clear and detailed. Ummmmmmmph........need more time and still cost issues to consider. Given past rare earth price increases.........?? But as a driver, it does have technical performance potential.

Will be interesting to compare to the current model. Notice the extended high range, slight increase in SPL and with a workable total Q. All credit to Evan.

Revc= 6.800 Ohm
Fo= 79.140 Hz
Sd= 36.317 cm
Vas= 3.331 Ltr
Cms= 1.778m M/N
Mmd= 2.148m Kg
Mms= 2.274 g
BL= 3.058 TM
Qms= 1.258
Qes= 0.822
Qts= 0.497
Levc= 6.410u H
No= 0.194 %
SPLo= 84.899 dB

Cheers
Mark.

Scottmoose 3rd November 2012 10:01 AM

Interesting. Big congrats. to Evan for his experimental work & design creativity. Looks like it has a little less electrical (and mechanical) damping than the standard driver, but nice flat response trend.

Hmm. I might be missing something, but according to the data, SPL is actually a little down compared to the stock unit (84.889db plays 86dB). Given the different sizes & slightly different scales of the graphs, it's difficult to compare accurately, but there doesn't seem to be much more additional HF extension either? SPLs at 20KHz look to be similar at ~85dB, and roughly 75dB at 30KHz.

Either way, nice driver, but on the present evidence I can't really see any reason to select it over the existing unit, especially given the cost of neodymium which will presumably mean it would need to be priced substantially higher. If it exhibits substantial improvements elsewhere, e.g. lower HD etc., then that's another matter, & I'm all for it.

markaudio 4th November 2012 12:24 AM

Hi Scott (Guys)
Apologies, yes SPL is a little lower than the existing Ferrite model. What happens when one try's to do things in a rush. I'll be back at our workshop end of next week as I'd like to explore with Evan, the possibility to increases the magnet strength on this prototype. There is some flexibility on the T/S indications that could allow us to push electrical damping a little more. Worth trying as we might gain extra SPL while boosting high range.

Cheers
Mark

18Hurts 5th November 2012 03:45 AM

The neo looks good,

It would solve the problem of a heavy magnet on a poly frame--since small speakers tend to be knocked around more, the lighter they are the better.
Did a gravity test on a surround speaker 2 meters up--the heavy magnet warped the speaker frame and it was game over. (Not a MA driver)

Neo prices are going down a bit, in the next year they should drop considerably since more mines are opening and going into production. Eventually I'll build a pair of MA speakers for my computer desk, I know those will hit the floor eventually so neo makes sense for that. The charts look good so looking forward to neo.

chrisb 5th November 2012 04:33 AM

Mark - how do you explain the rather significant difference in the impedance spikes between the neo and Alnicos posted in the other thread, and have any of these been listened to yet?

Henkjan 5th November 2012 10:16 AM

great! finally getting rid of these large magnets :D what would be the expected price impact (in %)

Scottmoose 5th November 2012 11:49 AM

Guys, Mark said it was an experimental pair, no more. As I read it, this is a one-off pair of units modified by Evan. Assuming something like it did go into production, before any kind of end price could realisitcally be determined, the cost of the new magnets, yoke, frame & tooling would need to be ascertained.

Henkjan 5th November 2012 12:04 PM

but he'll need a guestimate of the costs to make a descision to proceed....

Scottmoose 5th November 2012 03:51 PM

Give him chance. Mark's obviously only showing it to everyone for the sake of interest, and possibly to gauge general reaction. He's already said this driver is still in an early development stage, so any talk of end pricing is a wee bit premature.

18Hurts 5th November 2012 07:07 PM

It should not be too costly,

They are full ranges, not woofers or subwoofers so considerably less expensive since so much neo is not needed or desired.

In theory, I've heard neo "can" improve high frequencies so worth looking into. Might do the trick with the A10 and 12P since the larger drivers would embrace any additional treble response.

No stone left unturned with Mark--should be educational to see how this plays out. :scratch2:


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