does neodymium 'sound like' alnico?

[Iain McNeill]

Thanks Planet10 for referring this gem from the archives.

I'm going to have to read up on Barkhausen but I'm intrigued by the AC effects of flux modulation and whateverelse that, IMHO, are more important than the DC, steady state, quiescent B values in the gap.

I guess I'm challenging the fact that B is constant regardless of the current in the voicecoil.

The static flux produced by the magnet is a constant DC magnetic flow which saturates the motor magnetic circuit, right?

Could a strong enough voicecoil current produce an opposing field to bring the motor magnetic circuit out of saturation?

edit> that would sound bad right?

 

[Iain McNeill]

for the different magnets are different, combined with the design of the magnet, different sounding drivers.

Is the BH hysteresis curve frequency dependent? That would compound the problem.

 

[thoriated]

It's power dependent. Which of course means it's frequency dependent because of the complex impedance of a speaker changes the power delivered with frequency... But yeah, it's not so good.

DW seriously misrepresents the situation for home audio use, IAC, since he only considers the few dB at and past the very high end of the driver's rated power capability .

Alnico has superior resistance to flux modulation as compared to ferrite or neodymium up to the power at which it begins to demagnetize, which would be well into the area of permanent hearing damage for a pro audio driver used in a home installation.

 

[cajunner]

If that is the case, then I don't understand why many companies bother with schemes to dissipate the heat from the motor.

sorry to dredge this one up, but in the temperature variant, I was referring to the demagnetization cap on all the magnetic materials. The issues relating to power compression, glue failure ratios and coil delamination/former deformation/continuous power constraints, are another issue and I didn't mean to clump them together.

If anyone has a more current thread they know of that deals specifically with magnetic coercivity and flux modulation by conductive and non-conductive metals in either the magnet or the iron, please add the post topic here.

 

[danerius]

I have one alnico fullranger from an old tube radio. Surpricingly musical. But havent listened to that many alnico speakers other than that so I cant comment for speakers

But being a guitarists Ive tried a number of different pickups with ferrite and alnicos and the difference is quite clear. Alnicos are much more musical, responsive, clearer and oddly satisfying. With the ferrites Id be constantly adjusting the amp looking for... something...

With pickups magnets being much, much smaller price isnt that much of an issue so manufactures can pick and choose to higher degree so theres lots more variety for players and builders compared to loudspeakers. Guitar-pickup-amp-speaker is a different system with other variables but Im pretty sure there are just reasons why some audiphiles swear by alnico speakers. It cant be all down to different geometrys for different magnets

Regards /Bo

 

[bishopdante]

I'm not convinced this is significant. PA drivers like I mentioned above run far hotter and for far longer than any domestic driver in such a condition, and if there any such effects then they would be very evident.

I was told by a designer of high end monitoring systems that in the late 80s the people who were producing high powered neo magnet speakers for PA / studio monitor use by using massive magnetic fields, huge voice coils and tough neo magnets had big problems of the magnets melting the materials next to them, and etiher going out of alignment or even falling off. Sometimes even melted the basket. So these days they've toned down the amount of winding on the voice coil, and super powerful speakers still rely on ceramic magnets.