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Efficiencey: Neodymium Vs. Ferrite / standard

pablomigraine

pablomigraine

Commercial User
Feb 9, 2005
3,458
611
New York
neuraldsp.com
Disclosures
Director of Commercial Sales - Neural DSP
#1
I've heard alot about the expanded efficiencey of Neo speakers as far as doing more with a given wattage than regular speakers. Now, ignoring the weight benefits, whats the scoop? Is a top-shelf Neo 410 gonna give me more of the good stuff than a same brand non-neo given the same wattage? Basically I'm using 575 watt head that I wont get rid of for anything (Ashdown) but need more volume, so logic dictates more speakers, so if I move to a larger neo cab, will I underpower it?

what are the drawbacks of neo magnets in terms of tone, reliability etc?
 
#2
pablomigraine said:
I've heard alot about the expanded efficiencey of Neo speakers as far as doing more with a given wattage than regular speakers. what are the drawbacks of neo magnets in terms of tone, reliability etc?
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Neo drivers aren't any more sensitive, they just have lighter weight. As for the rest, flux is flux, a voice coil doesn't care what the source is.
 
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#3
billfitzmaurice said:
Neo drivers aren't any more sensitive, they just have lighter weight. As for the rest, flux is flux, a voice coil doesn't care what the source is.
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Bill,

What are your thoughts on the longevity and tone of neodymium drivers?

I like the idea of reduced weight, but not at the price of short life and poor tone.
 
#5
Neodymium drivers are not a problem as far as life goes. The only problems with Neodymium is that under heat, they do lose their power. But the kind of heat needed to do that would not be present in a speaker situation, unless you were to fry something, and that still wouldn't heat the magnet itself enough to do that.

About underpowering... I don't think you will have a problem. I do tend to like speakers that are moving, not ones that are just barely vibrating (usually in a situation where there is a lot of them). With a 410, your 575 watts would be plenty.
 
#6
While I am far from being the main speaker expert on this forum, I have looked into the physics side of speaker design in some detail. One observation is that magnetic field strength affects not only efficiency but also frequency response, because it controls electromagnetic damping. Thus you can't increase the field with reckless abandon. The two-out-of-three rule (little, loud, and low, pick any two) is tenacious.

High frequency and off axis behavior aside, you can increase efficiency by (approximately) increasing cone diameter and magnetic field at the same time. But this can be done with both neo and conventional magnets.
 
#7
12bass said:
Bill,

What are your thoughts on the longevity and tone of neodymium drivers?

I like the idea of reduced weight, but not at the price of short life and poor tone.
Click to expand...

I play through a GK NEO212. Neodymium speakers supposedly have a more pronounced midrange than alnico/ceramic speakers. Don't know if this is true. Neo magnets also corrode very easily when exposed to air so they are sealed in a resin. Also Neo magnets supposedly start breaking down at 150 degress versus 450 for alnico magnets.

This may sound pretty horrible but I have yet to hear any complaints about fried neo magnets. It's been a long while since I've researced this so please feel free to correct me if I'm wrong.

Bottom line: I love my Neo cab and have no qualms about it's life expectancy.
 
#8
12bass said:
Bill,

What are your thoughts on the longevity and tone of neodymium drivers?

I like the idea of reduced weight, but not at the price of short life and poor tone.
Click to expand...

Another member from S'toon!

As squidfinger posted, certain NeFeB compounds start to have irreversible magnetic losses at temperatures about 150 C. I find it highly unlikely that a loudspeakers magnet exceeds even 100 C.
 
#10
Geoff St. Germaine said:
Another member from S'toon!

As squidfinger posted, certain NeFeB compounds start to have irreversible magnetic losses at temperatures about 150 C. I find it highly unlikely that a loudspeakers magnet exceeds even 100 C.
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Hello Geoff,

I'm a friend of Sheldon D. as well.....

There has been some talk on the Eden forum about neodymium drivers not lasting in the field. Eden is working a neo designs, but seems to be saying that there are serious problems with using neodymium in the long term, problems that need to be addressed before they release their neo line.

Here's a couple posts from the Eden forum on this issue:

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2) There are also some very serious long term issues with some of the standard Neodynium magnet material and speaker designs currently offered. Many of the speakers currently in service suffer from this problem. It is not talked about very much, as Neo is a very hot buzz word right now. The Neo is very nice for portable systems because it offers much lighter weight for a given speaker design than does the standard ceramic magnets. It is a very neat material but needs some very special engineering considerations to work in our applications. The big drawback with Neo speakers is that if you heat up a Neo magnet structure past a certain point ruffly 212 degrees F or so (depending on the Alloy type), the Neo material looses some magnetic (flux density)energy permenantly. Every time you do this a change occurs, over time the sensitivity (efficency) of the speaker will start to go down it will continue to drop lower and lower and it will not come back up to where it was originally. This happens to a much smaller degree with conventional speakers but they return to original flux and efficincy levels after they cool down. This is a difficult problem to recognise as it generally happens slowly over a period of time. One other note, typically on the Neo speaker offerings you will find that they do not sound the same as the previous products they replaced. That could be a good or bad thing depending on your perspective. We will be adressing all these issues with some very cool new products in the future. The Nemesis by the way is going very well and is much lighter that standard gear out there ( about 38 Lb. for a 250W 210 Combo) you can look for some more good stuff there in the future as well. Take care

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Pika, the only way to save weight yet retain quality would be to go with neodymium drivers. Changing the wood will effect durability as well as sound. As for the neos, we're still working out a few bugs...like how to keep the magnets from degrading in a year or so...which is the main problem with neos. Who really wants to swap drivers every year or two?

But...as I said, we're working on it. And as soon as David is happy, he's going to send me a neo-equipped 212XLT to test.
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#12
seamonkey said:
There's many sound reinforcement companies using neo's and not experiencing these problems.
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JBL Vertec's for one.
I suspect Eden's issue is more along the lines of they don't have drop in replacement neo's with the same specs as their current drivers.
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Tooling is the more likely problem. They can't afford to do so when they only produce is enough to meet their own needs. Ceramic will disappear within ten years now that the cost of shipping a 25lb driver can equal the cost to produce it. I just received a shipment from Eminence and not only do they look and sound really good, they weigh practically nothing.
 
#13
12bass said:
Bill,

What are your thoughts on the longevity and tone of neodymium drivers?

I like the idea of reduced weight, but not at the price of short life and poor tone.
Click to expand...


This is the point man...

quality neo speakers with the same longevity of the normal one should cost double the price of the speakers you find in normal cabs (and are also a little bit heavier), but this is not possible if you still want to have affordable neo cabs on the market.
 
#15
seamonkey said:
This is really good news. I can't wait to see what you do with them. Is there any details you can share?
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All I can say so far is that they look sweet, I'll be mounting them in some of my cabs and testing them when weather permits, but that's done outdoors and I'm in God's Country (New Hampshire to those of you not fortunate enough to live here) so that could be aways off.
 
#16
Squidfinger said:
I play through a GK NEO212. Neodymium speakers supposedly have a more pronounced midrange than alnico/ceramic speakers. Don't know if this is true.
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Nope. Field is field. Differences in sound are more likely due to conscious design choices that are independent of the magnet material.
 
#18
seamonkey said:
Didn't this topic come up back when ceramic magnets replaced alnico?

Alnico magnetic field is stronger than ceramic, Alnico has the best temp stability ... Alnico is a lot more expensive.

Neo's are here to stay, they'll be cheaper in the long run.
Click to expand...


I belive you said it all in the above highlighted statement.
 
#19
fdeck said:
Nope. Field is field. Differences in sound are more likely due to conscious design choices that are independent of the magnet material.
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The new Eminence neos do sound a lot better than their old neos in the midrange. The old ones used a heat sink on the polepiece and a porous dustcap so that it could breathe, and the porous dustcap killed the midrange. The Deltalite IIs have a solid dustcap, which acts as a midrange radiator for much better mids. This gives them a tone much more akin to ceramic. The new 2510 has a bottom almost as good as a BP102 and a high end better than a Delta 10.
 

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