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markaudio 2nd November 2012 05:57 AM

Alnico Experiment
 
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Hi Guys,
This new thread is a follow-up on the Alnico topic:

http://www.diyaudio.com/forums/marka...o-magnets.html


Take a look at this experiment designed and built by Evan Yu. It consists of Alnico magnet held in steel U yoke. A CHR70 frame was re-machined to take this experimental Motor Set. The Power Train is from a standard third generation CHR.

The outcome is very interesting. As predicted, the relatively weak MEP (Maximum Energy Product) of the small mass Motor Set produced a low SPL (around 75 average). Of greater interest is the unexpected boost to the high range (exceeded our standard anechoic line measurement @ 40kHz (tolerance > 35kHz is +/- 2.5dB). We usually expect to see a fall-off > 35kHz but we detected a climbing response, rather unusual. The test driver maintained a near flat response. Due to the low output, the driver is outside the tolerances set up for our standard LMS T/S test.

The next step is to increase Motor Set mass but there’s more testing before this next step. The issue of future mass production cost will also be up for consideration.

In terms of perceivable musical output, we’re some way off the listening and review stages. Musical beauty will be in the ears of each listener so I can’t say Alnico will "improve" the sound. It might possibly deliver some measured performance benefits, but we’re some way off from knowing final outcomes and as already stated, "bang for the buck" (cost V performance gain) will be on the agenda.

Cheers
Mark.

Scottmoose 2nd November 2012 09:13 AM

Very interesting.

Obviously the powertrain will need some redesign as expected to compensate for the change in magnet / yoke design affecting the rest of it. The FR is reasonably encouraging though if nothing else. Response on the bottom end has changed -is that a measurement artifact from your being outside the usual LMS tolerances you have for the CHR et al? Or has the mass-corner increased? Since the powertrain is stock, it looks like you've got more electrical damping from it, despite the reduced MEP.

I'd probably suggest that any future production unit (mists of the distant future) would be better based on an Alpair rather than the CHR, but I reckon using the cheaper unit is a bit more economical for experimenting on... ;) Possibly with the MAOP cone or similar, for a full-on SE driver.

buzzforb 2nd November 2012 09:33 AM

I dont know if it will ultimately work out, but I think there is a market for Alnico based FR units. You really only have Lowther and AN, that I know of. Lowther is out of most peoples price range and many models are not well regarded. The AN's have a following, but seem to have just as many detractors to match. I can say I would be very confident in a product coming from you and your team and would be watching in earnest, just like I am for MAOP 7

Assesears 2nd November 2012 12:11 PM

I hope Mark continues his experiments, being an engineer myself I find his work of interest. Impressive response looking forward to what he can achieve.

Regards

Barleywater 2nd November 2012 12:52 PM

In "is there a possibilty of seeing some MA Alpairs with alnico magnets? #17"

Quote:

Personally, I'll continue to use my Applied Mech. Eng. experience to evaluate all materials on these criteria:

1- Engineering criteria (design, production and assembly)
2 - Value for money (will a material and/or component perform better given for a given cost)
And here performance is being assessed.

What are performance differences in materials? Is rare earth magnet conductive? Ferrite certainly isn't good conductor. How smoothly do magnetic fields move through each?

Barkhausen effect noise is easily demonstrated with ferrite magnets.

It looks like you are in a great position to explore this effect with Alnico materials.

Andrew

Scottmoose 2nd November 2012 02:09 PM

A minor point, but AlNiCo isn't a rare earth magnet, which the above appears to suggest.

chrisb 2nd November 2012 04:48 PM

Quote:

Originally Posted by Scottmoose (Post 3225087)
A minor point, but AlNiCo isn't a rare earth magnet, which the above appears to suggest.


well, perhaps not "rare", but certainly not as common as ceramic types :rolleyes: - sorry, I couldn't resist

Mark:
of course you realize that once you open Pandora's box .....

somehow that sounded pervy

mattlong8 2nd November 2012 05:48 PM

It is not a rare earth magnet, at least aluminum nickel and cobalt aren't. Perhaps there is some brand that throws a bit of samarium in the mix which is a rare earth magnet. the nice thing on the production end of these magnets is that nickle and cobalt are often found in the same ores.
I wouldn't be surprised if we see these increase in popularity as the price and availability of Nd rises, mostly due to China's growing middle class/domestic electronics market.

tinitus 2nd November 2012 05:53 PM

I think it comes in different qualities
you can find cheap drivers using small alnico magnets
on its own, not that much special

actually, it might be possible to buy them in small standard sizes from the same place where people buy their neo magnets for the diy planar and ribbon speaker projects

but ofcourse, it always gets very expencive if you want something special

chrisb 2nd November 2012 07:04 PM

Quote:

Originally Posted by mattlong8 (Post 3225378)
It is not a rare earth magnet, at least aluminum nickel and cobalt aren't. Perhaps there is some brand that throws a bit of samarium in the mix which is a rare earth magnet. the nice thing on the production end of these magnets is that nickle and cobalt are often found in the same ores.
I wouldn't be surprised if we see these increase in popularity as the price and availability of Nd rises, mostly due to China's growing middle class/domestic electronics market.


It's likely the other side of the China equation - i.e. monolithic control of all aspects of the economy by the Communist party, and its ability to hold the rest of the globe hostage due to their production predominance of this material that has as much to do with the roller coaster ride the market price has enjoyed over the past couple of years as the consumption by their burgeoning domestic consumption of such products.

I could be wrong, but even with the benefit of 20/20 hindsight, economics experts & historians don't always agree, and predictions are worth the paper they're printed on.


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