neodymium speakers ?

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v-bro

v-bro

Member
Joined 2006
Just an example (if I may post so...):
http://www.partsexpress.com/pe/showdetl.cfm?Partnumber=290-020
and:
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=290-015

Think any manufacturer using an expensive alnico magnet will design the rest of the driver with the best of materials. Probably this will cloud all objectivity in listening experiences, there are many fine sounding drivers made with ferrite magnets as long as they were built with the same care.

Cheap materials can many times work just fine, but manufacturers of low-end drivers will be more likely to use these materials most.

It's all in the design and I figure neodymium offers a greater potential than any other material when used properly.
 
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AndrewT

R.I.P.
Joined 2004
Hi,
Tannoy have reverted to alnino in lieu of ferrite for their top of the range Westminster.
I am fairly sure they could have used neo and saved some cost if they thought they could get the performance out of neo.
They chose alnico in spite of the cost.
Make up your own mind.
 
v-bro

v-bro

Member
Joined 2006
This is another informative quote about alnico, it explains why it's more suitable for guitar speakers or other applications of high abuse....


"The whole 'AlNiCo mojo' is about smooth compression at high average levels, such as what you would have running the amp flat out. AlNiCo (Aluminum-Nickel-Cobalt) is an alloy magnet and all alloy magnets are easier to demagnetize than comparable Ceramic (Strontium Ferrite) magnets. What this means is that 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 small magnets near the surface of the magnet poles (called 'domains') 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 some players say ceramics sound a little edgey at high average levels as opposed to AlNiCo. However, by properly designing the entire magnetic circuit, Ceramics can be made to behave quite well for desireable guitar amp tone and dynamics. You might compare the two magnetic circuits to solid state amps versus tube amps, where the solid state amp gives it all its got then clips hard, while a tube amp compresses nice and smooth. The extension of this idea, then, is that with the AlNiCo, like the tube amp, you can seem to have a louder average volume since it gets compressed smoothly. By the way, the compressing or demagnetization that occurs with the AlNiCo is not permanent. It springs right back to its design operating point.

A voice coil is like an electric motor. The bigger the voice coil, the more wire used, the more torque or pulling power you have to move the cone. With the proper match of components, you can get more sensitivity, wider frequency response, and more power handling ability." [/B]
Click to expand...


From this thread:
http://www.jameshadfield.com/forum/viewtopic.php?p=201&sid=46f1cf55aca191e9a35b3fb0b0d26931
 
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AndrewT

R.I.P.
Joined 2004
v-bro said:
"Neodymium has the best technical performance of the three but is also the most expensive. Ferrites are generally far less costly than Alnico".

From this text:http://www.tonetubby.com/alnico.htm
Click to expand...


Hi all,
there are a couple of statements in the link that seem unfinished/unfamiliar.

1. no mention of the temperature at which each of the three common materials start to lose magnetism.
I believe that neo and ferrite degrade at a similar temperature. Is this true?
I believe that alnico degrades at a significantly higher temperature than the other two (maybe as much as 50Cdegrees). Is this true?

2. the article states that neo & ferrite revert to their original magnetism when they cool. Is this true?
and that Alnico permanently loses some or all of it's magnetism when heated. Is this true?

Comparative figures would be appreciated to enable a real assessment of the technical qualities of each magnetic type.
 
badman

badman

Member
Joined 2003
pothaudio.com
Backwave

As somebody mentioned, I'd say this is a big reason to use neodymium or alnico. Zaph and others have documented how the backwave of a woofer/midwoof/etc is influenced by mounting, no reason a smaller frame with more 'breathing room' shouldn' t have similar advantages to a careful mounting scheme, and quite likely on a higher order.

Oh, that galaxy audio driver looks pretty decent... until you see the response curves) Totally useless :)
 
T

thoriated

Member
Joined 2003
Unless you plan to beat a speaker to within an inch of its life, or expose it to large mechanical shocks (as by dropping) alnico is the best performing material technically of those discussed. Alnico's one real relative weakness is that is can be 'permanently' demagnetized (until and whether it is subsequently remagnetized, that is) by massively overdriving the speaker (although it is possible to design alnico magnetic circuits that are fairly immune to this). Operated within its limits as far as remanence, alnico has by far the least sensitivity to temperature and opposing magnetic flux compared to either mud or neodymium. Neodymium's Curie temperature (at which the magnetic material effectively loses its magnetic characteristics) is about 300C, ceramic around 450C, and alnico around 850C. The Curie temperatures have fairly direct relationships to the magnetic materials' reduction of magnetic flux from rising temperatures.
 
v-bro

v-bro

Member
Joined 2006
Ok, but will temperatures rise high enough to have the magnetic flux decrease to a lower level within neodymium than 'mud or alnico'. Since neodymium 'starts' at a higher flux level.

I wondered if alnico is a better choice to create a driver (with measures against demagnetizing offcourse) that can produce reasonably 'audiophile' sound at low levels and still be able to go loud..in other words: "is alnico a better choice to let 'hifi meet PA'?"...

That's what draws me to the galaxy audio neolite 5" driver, creating a good portable speaker for outside use (on a bicycle...lol) on a battery. (lipoly?) I'm looking for a small and light fullrange driver that can sound reasonably nice at lower levels, but can go loud enough for little partys with max. 30 heads...for as long as possible on the battery...(don't really mind if it takes several small boxes, but prefer a maximum of four)...and using small class D ("class T") amplifier(s)...
 
T

thoriated

Member
Joined 2003
You raise some good points. Alnico may not generally be the preferred choice for professional sound reinforcement, except where high sound quality trumps maximum SPL with the minimum number of drivers. A well designed ceramic magnet driver using a flux shorting ring can be very good sounding.

From what I gather, the main attraction of neodymium magnet assemblies for prosound is light weight - a driver of given nominal efficiency and power handling can weigh less than half its equivalent using a ceramic magnet. The first generation of ceramic magnet speakers typically weighed 15% or more than their immediate alnico predecessors, btw.

FWIW, alnico is the most least temperature dependent within its operating parameters. I would expect neodymium to sound better than ceramic, generally speaking. Ceramic magnets, due to their non-conductive nature, are prone to higher harmonic distortion generation when flux shorting rings are not used (JBL uses flux shorting rings in most, if not all of their LF prosound drivers to avoid this).
 
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