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-   -   is there a possibilty of seeing some MA Alpairs with alnico magnets? (http://www.diyaudio.com/forums/markaudio/221216-there-possibilty-seeing-some-ma-alpairs-alnico-magnets.html)

DeonC 9th October 2012 07:44 AM

Is there a possibilty of seeing some MA Alpairs with alnico magnets?
 
Hi Mark

I was just wondering, are you or will you consider making the Alpair drivers with alnico magnets? I for one add a very strong vote in favor of this.

Thanks,
Deon

Scottmoose 9th October 2012 08:23 AM

I don't. AlNiCo costs a fortune and many forms are extremely vulnerable to demagnetization. Although people often talk about the 'tone' of AlNiCo, we don't listen to magnetic fields, so this is a question of motor design taken as a whole: magnet material, VC, flux density in the VC gap, pole-piece, front / rear plates & shape, the lot, not just the magnet material. Aside from the cone, I doubt there would be much left of the original driver since the frame & suspension would likely need to be changed too, assuming what is desired is a well engineered unit & not just an existing driver with an AlNiCo magnet stuck on the back on the assumption that it is 'better.'

nicoch58 10th October 2012 08:13 AM

HI
the alnico like nikel in opt tranformer react different , plus the design is very different... jbl in the past work hard too swap the magnet for the cheaper ceramic.. the copper ring is invented to compensate all the problem , btw the alnico is better and sound better , speak with a guitar player know this very well, in speakers is quite easy to ear the difference of the alnico one , try !
is normal swap the bar magnet, (a simpli bar) in pickup humbuckers to change the sound , alnico 2,3,5,8 and ceramic ...

lowter user know well...ask to Pass

For me the markaudio is too good and a top fr need to be in alnico and OB ready.


Nice and better alternative is field coils , this can change qts/db on the fly...

chrisb 10th October 2012 05:39 PM

The "science" / production processes for ceramic composite magnetics are reasonably mature and affordable - the costs / availability associated with strategic materials required for Alnico or for that matter Neodymium must be daunting for a small manufacturer.

As for Field Coils, the even greater total cost and manufacturing complexity aside, I've yet to see one whose mass could be accommodated with the cast resin frames that Mark has employed on all his drivers to date other than the EL166/Woofer 6

In any case, the method of creating the magnetic flux is but one part of the motor design, which is itself but one part of a total transducer design. I'd vote for Mark to continue with this current work on suspension and cone materials/profiles - AFAIC the results speak for themselves

nicoch58 10th October 2012 07:04 PM

and :
Now to factual differences. There are three main advantages of Alnico over ferrite:
1) greater immunity to flux modulation
2) greater heat stability.
3) greater suitability to shielded applications

There is also one significant disadvantage – Alnico is susceptible to demagnetization due to large voice coil currents.
None of these differences are absolute. It is possible to design out all of the limitations of each material. However the issue becomes one of cost.
Ferrite designs can equal or exceed an Alnico magnet’s flux stability with the addition of a copper shorting ring around the pole piece. With the use of vented cooling and heat sinking, you can manage the heat build-up on a ferrite driver to where it stays below the threshold of non-linear response. Finally with the addition of secondary magnets, you can shield the motor of a ferrite driver to the same degree as an internal ferrite equivalent.

In the same manner, Alnico drivers can be engineered to be immune to demagnetization from overpowering. JBL has done this though the use of a series of flux stabilization rings in their new 1500AL driver. However it is extremely expensive."

Source: Don McRitchie: http://www.audioheritage.org/vbullet...Ferrite-Debate
[B]Note: The McRitchie article sites no references of any kind to back up his statements so can-not be considered authoritative. It is interesting and makes some good points, but remains "indicative".

FullRangeMan 10th October 2012 08:00 PM

All speaker magnet send a NFB to the amp, and the Alnico magnet NFB made the amp sound better to the brain.

But I would prefer a big Field Coil motor to the driver reach hi SPL(100dB or more) to use small tube amps.

markaudio 10th October 2012 11:34 PM

Hi Guys,
Always allot of opinions on this topic, much stated as "fact" without any back up references. Let me ask members for more clarity:

nicoch58: You've made this statement:

jbl in the past work hard too swap the magnet for the cheaper ceramic.. the copper ring is invented to compensate all the problem , btw the alnico is better and sound better

You should know that my associate Jeff Taniguchi San worked for JBL, produced several speaker system designs for them in a 10 year period. I use the same Japanese Coil maker as JBL. We share some of the technology. Please state your source/references for the statement you make. Who in JBL gave you the information you state?

Where did you find this statement? Please post the link

found this :
"The answer lays in Alnico's smooth compression at high average levels. This effects sound simmilar to tube's soft clipping at high outpout powers. Alnico is an alloy magnet and all alloy magnets are easier to demagnetize than comparable ceramic (Strontium Ferrite) magnets. As the voice coil starts moving in response to the input signal, it generates a magnetic field of its own that tries to demagnetize the magnet. As its effect lowers the available magnetic field of the alnico magnet, the speaker becomes less efficient, the voice coil moves less, etc. The physics of it is that the magnet domains near the surface of the magnet poles begin to change state, or flip directions. The result is smooth compression, the same kind of operating curve compression that occurs in a tube amplifier. The ceramic magnet, on the other hand, doesn't compress or demagnetize as easily, so the voice coil moves to its mechanical limit and won't go any farther. This is why many say ceramic magnets sound a little edgey at high average levels as opposed to alnico. If we continue with tube/solid state comparison, then alnico behaves tube-amp like and louder average volumes can be achieved but with smooth compression. The compressing or demagnetization that occurs with the AlNiCo is not permanent. It's domains spring back to their initial state."


I'll allow this post to remain for a day or so without a reference to its source.

---------------------

Fellas,

I'm all for debate but when making statements like member nicoch58, back them up with references and links to the research. Take care to check your reference carefully for credibility and reliability.

Thanks
Mark.


Thanks
Mark.

DeonC 11th October 2012 06:23 AM

Hi Mark

The main reason for me asking is that many respected guys and designers in the audio community have stated that alnico has a better tone than ceramic. Lynn Olson is one of them, and I have heard it said too many times to dismiss it. Field coil is also said to have great tonality, but that gets too expensive. I am not asking for a huge hulking alnico slug so that efficiency will skyrocket, but OTOH even a similar sized magnet will up efficiency usefully. My reason is that I think it will make an already great driver even better. Now even Lynn admits that you cannot measure the difference alnico makes, but in a good system it is audible. I know the alnico units will probably cost more, but I do think it will be worth it.

Enjoy,
Deon

nicoch58 11th October 2012 09:08 AM

HI Mark what you think about alnico ? glad to know about


"btw the alnico is better and sound better" is my idea (btw)no jbl source ,fell free to delete my post , what I write is found on web forum nothing scientific.. but coincide at last of lot year of serf on web , we know there are myth around...but the data is quite consistence

in the end the alnico is too time around , we can all thinks that are good material for speakers, my personal esperience with alnico is nice , and look like that lowther -supravox - phy-hp love too

nicoch58 11th October 2012 09:40 AM

btw the info are from webers speakers faq

reference Let's Talk Speakers


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