The magnet material does not "sound". The various geometries in combination with the magnet materials might affect the sound though. What matters in the end is the strength and geometry of the magnetic field in the space around the voice coil.
Different magnet materials have different properties which leads to different shapes of the motor for the same magnetic field. This means that two drivers that look very different in principle can behave exactly the same.
Neodymium magnets are smaller for the same magnetic strength, this is obviously advantageous when a small driver is desired.
Different magnet materials have different properties which leads to different shapes of the motor for the same magnetic field. This means that two drivers that look very different in principle can behave exactly the same.
Neodymium magnets are smaller for the same magnetic strength, this is obviously advantageous when a small driver is desired.
It costs less to ship a driver that weighs less, especially a lot of them which may end up meaning the neo version is chosen for pragmatic reasons.pinkmouse said:
Newer Neo magnet drivers usually involve a comoplete redesign, with the attendant possibility to make detail improvements to the design. Or stuff it up, as the case may be..
Let us look at it from a physics POV.
1: The energy transfer between the magnet and VC is given up in energy produced and energy lost in the production, as heat.
2: Different magnetic materials have different "curie" points , or the point in temperature all magnetic flux is lost. This is not a linear curve but approching a log curve.
3: As the magnet heats there is a loss of flux strength due to the increased molecular activity and the ever increasing loss of polar alingment.
4: As the VC heats there is a rising resistance due to molecular distance being increased and the addition energy required to make the electrons jump to a further distance point.
Simply stated: The Qts changes as the motor heats up as there is a loss in efficency due to efficency being given up in heat and the associated effects.
ron
1: The energy transfer between the magnet and VC is given up in energy produced and energy lost in the production, as heat.
2: Different magnetic materials have different "curie" points , or the point in temperature all magnetic flux is lost. This is not a linear curve but approching a log curve.
3: As the magnet heats there is a loss of flux strength due to the increased molecular activity and the ever increasing loss of polar alingment.
4: As the VC heats there is a rising resistance due to molecular distance being increased and the addition energy required to make the electrons jump to a further distance point.
Simply stated: The Qts changes as the motor heats up as there is a loss in efficency due to efficency being given up in heat and the associated effects.
ron
There is a great deal more to this than stated above. I am just stating the obvious.
If the VC is closer to the maxium intensity gauss of the magnet then there is a greater transfer of energy.
As the VC moves away from the maximum gauss point then there is less electromotive force and the the cone movement is less controlled as there is less energy transfer to controll the mass.
Thats a drawback of large X-max drivers. But if their application is in the lower frequency reigons then the mass inertia effect is less as the human ear dosent respond to low frequency distortion as it does to high.
This is an interesting subject.
ron
If the VC is closer to the maxium intensity gauss of the magnet then there is a greater transfer of energy.
As the VC moves away from the maximum gauss point then there is less electromotive force and the the cone movement is less controlled as there is less energy transfer to controll the mass.
Thats a drawback of large X-max drivers. But if their application is in the lower frequency reigons then the mass inertia effect is less as the human ear dosent respond to low frequency distortion as it does to high.
This is an interesting subject.
ron
ronc said:
It certainly is. Just as a matter of curiosity, could you simulate or calculate these effects with the different magnets? I believe your physics is correct, but having a graph or numbers to show the extent of the problem would be very revealing. Certainly in normal use, my home drivers never get significantly above room temperature, and even with pro drivers that have been heavily, (but sensibly) used it's quite possible to touch them comfortably, so I doubt the magnets get over 50-60 degrees C. Would these temperatures cause magnet problems with your model?
It is very interesting. AlNiCo magnets are more prone to demagnetising than ferrite / ceramic. Dismantle a alnico motor, and the magnet will want recharging. That is why they must be stored with keepers across the poles. They are also more prone to the effects of external fields, they are easier to degauss.
Ceramic on the other hand, has a much higher residual magnetism, they don't need keepers.
Currie temperature does vary with materials, but I would have left the building long before that. IIRC AlNiCo is higher than ceramic, see http://www.magnetsource.com/Solutions_Pages/CERAMICproperts.html
But why one material should sound different to another is beyond me. I have heard / owned drivers where the only known difference was the magnet type. I suspect if there was a difference, it could be due to the amount of air trapped behind the dust cap.
Yet others, whom I respect, hear a difference.
Geoff
Ceramic on the other hand, has a much higher residual magnetism, they don't need keepers.
Currie temperature does vary with materials, but I would have left the building long before that. IIRC AlNiCo is higher than ceramic, see http://www.magnetsource.com/Solutions_Pages/CERAMICproperts.html
But why one material should sound different to another is beyond me. I have heard / owned drivers where the only known difference was the magnet type. I suspect if there was a difference, it could be due to the amount of air trapped behind the dust cap.
Yet others, whom I respect, hear a difference.
Geoff
Geoff, I'm sure that Lowthers, for example, do sound different with different magnet types. I just think that it's more to do with having a "unique selling point" for those drivers rather than the actual physics of the magnetic material. PD/Turbosound proved to me that it is possible to make a driver sound identical with only a difference in magnet type, (as they have to, as these drivers need to be compatable with a huge installed user base of existing drivers). Where we go from here I'm not sure! 
Hi Al. Yes to all. Dave G in BC has also reported the difference. I have not picked it in early Wharfedales, when they adopted ceramic.
I tend to want to find out why. Unless there is something we don't understand about magnetism, a line of force is a line of force.
Comparing alnico with ceramic, most people say alnico is better. The field from alnico is more likely to be modulated by the field from the VC, which would make the alnico inferior. There has to be more to it.
An alnico motor generally has more mass in it. More for the cone to work against, rather than vibrating the frame. That would also indicate field coil motors are way out in front.
I can add/remove magnet/mass on my current project. With the extra, I have an increase in SPL (3dB) and an apparent improvement in clarity. The extra magnet would double the mass of the motor. CSDs may shed some light.
But where does that leave neodymium?
Geoff.
I tend to want to find out why. Unless there is something we don't understand about magnetism, a line of force is a line of force.
Comparing alnico with ceramic, most people say alnico is better. The field from alnico is more likely to be modulated by the field from the VC, which would make the alnico inferior. There has to be more to it.
An alnico motor generally has more mass in it. More for the cone to work against, rather than vibrating the frame. That would also indicate field coil motors are way out in front.
I can add/remove magnet/mass on my current project. With the extra, I have an increase in SPL (3dB) and an apparent improvement in clarity. The extra magnet would double the mass of the motor. CSDs may shed some light.
But where does that leave neodymium?
Geoff.
Geoff H said:
This looks like a reasonable mechanism. The drivers I heard were crossed over to at about 150hz IIRC, so any problems with the larger excursions required to produce bottom end causing resonances/IM distortion would be minimised. The PD drivers were of course, also much bigger and more heavily built than domestic ones, and this may well have had an effect.
Geoff H said:
My experience is that it is purely the coercive force that you "hear". It's really quite low on AlNiCo, meaning that gap flux modulation from the voice coil is a lot bigger of a problem with AlNiCo than neo or ferrite. Flux modulation adds a lot of even order harmonics which can be quite euphonic. Ferrite and neo take a LOT more voice coil flux to have any kinds of these problems.
Much like the low power tube versus high power solid state debates - how much clipping and what type of distortion spectrum you want are the big basis for the subjective preferences.
That is 100% dependent upon the voice coil and motor structure design. It can be 10W, it can be 1000W - depends upon the design of the speaker.
However, it tends to happen at levels 1/4 to 1/8 that of neo and ferrite speakers. So for a given design where you can swap neo and AlNiCo without a loss in gap flux, you'll find the AlNiCo starting to compress at 1/4 to 1/5th the power of the neo.
However, it tends to happen at levels 1/4 to 1/8 that of neo and ferrite speakers. So for a given design where you can swap neo and AlNiCo without a loss in gap flux, you'll find the AlNiCo starting to compress at 1/4 to 1/5th the power of the neo.
Eeek, that's a lot worse than I would have imagined. Pardon me for the question,(I'm unfamiliar with magnetic flux theory), but is that compression frequency dependant as well, or fairly linear, putting aside the power distribution in the music signal?
edit: Oh, and good luck with the new business!
edit: Oh, and good luck with the new business!
this thread, and another on this topic, has me intrigued, so much so that I decided to join the forum specifically to address it.
not being the wiser, and with little physics/electrodynamic learning under my belt, I would like to know if I understand what's being purported so far-
to simplify, I am going to substitute the emf of the motor, with b, and the emf of the coil with l, if that is ok.
if I am to understand this correctly, alnico has a stronger ability to resist the flux modulation, which would allow a light, paper cone to more accurately produce transient information, but within a low power scheme, as alnico "breaks" and loses permanent remanence?
I am confused by the statements about how alnico loses magnetism. I was under the impression that alnico is "faster" and neo is "stronger" and ceramic was neither fast or strong, but "bulky"... without any of the temperature arguments, which I believe have been dispelled thoroughly, alnico has a stronger resistance to flux modulation, right up to the point where the l causes demagnetization, and from what I've read about the TAD vs. JBL, it's why the power compression is so significant in the TAD?
I want to believe that you can get by with neo and ferrite, but for the best, cost no object designs, why are the four-figure drivers still using the alnico? Can it really be only because the salesman said so, and the built-in profit potential from re-magnetization routines allows what amounts to a second purchase of the same item? Like Hendrix with his paper coiled Lowthers, if you have the money...?
I think in a full-range context, alnico has an advantage in its ability to render some material at a resolution that ceramic and neo cannot, if it is indeed true that it resists changes in flux density better. Is this refutable?
I theorize dan is more concerned with the large signal, reliability issues that gives ferrite an advantage in reproduction, besides the cost issue, but what I think is being skirted about is whether the magnetic material actually possesses different "speed" in its field strength recoveries, for lack of a proper definition, or that it's possible to move a mass back and forth within a field, that staticly is identical, but once it's being pushed against, isn't the same?
You can't use the Lowther analogy either, because the reason they do sound differently is based on differing motor strengths, as well as additional cobalt alloys used in the pole and field, I guess the same is true with the GOTO stuff, and even the Gauss brands.
I know the force is applied through the pole and plate steel, but perhaps the "speed" is really because the alnico motor puts the magnet closer to the gap, and the distance between the pole and the field is where the "speed" is lost, in the steel's return path, or not...
is the steel being saturated in the pole plate in alnico designs from putting the gap closer to the magnet, for the same amount of force, as a ferrite ring will be further from the gap, based simply on magnetic density requirements needed to optimize the magnetic potentials, and the accompanying steel return path in a ferrite design will be longer, allowing inconsistencies in the steel to have a greater effect? Somebody say this is patently false, right? If this were true, the neo-radial design that puts the magnet in direct contact with the gap, would be the "best", but apparently that isn't so either because of the extremely long steel return path?
I guess what I don't understand, is this "coercivity" definition, as it's being used.
I understand coercivity to be the resistive ability of a magnetic material to changes in permanent strength, and not the resistance to "coersion, or coercive force" of the l to overpower b, is this right?
In other words, the field that ferrite produces is easier to temporarily modulate than the field alnico produces, given the same strength, but as you go up in power, the ferrite's field easily reverses, but the alnico won't, once it reaches that knee of temporary/permanent?
and another thing, this alnico/tube relationship, is based on the fact that as a low power tube has poor damping, maybe the alnico's greater resistance to flux modulation is a reason why people like the sound? In that using alnico is simply like adding damping factor to the amp? Or why field coils sound so nice, because they have a constant and unchanging source of emf?
for that matter, is alnico "slower" than field coils? and do field coils have the strength to stay saturated in lieu of 3 kilowatt inputs?
I imagine that would have to be quite a field coil...
I love this stuff.
Oh, and hello, everyone, where's my manners...
not being the wiser, and with little physics/electrodynamic learning under my belt, I would like to know if I understand what's being purported so far-
to simplify, I am going to substitute the emf of the motor, with b, and the emf of the coil with l, if that is ok.
if I am to understand this correctly, alnico has a stronger ability to resist the flux modulation, which would allow a light, paper cone to more accurately produce transient information, but within a low power scheme, as alnico "breaks" and loses permanent remanence?
I am confused by the statements about how alnico loses magnetism. I was under the impression that alnico is "faster" and neo is "stronger" and ceramic was neither fast or strong, but "bulky"... without any of the temperature arguments, which I believe have been dispelled thoroughly, alnico has a stronger resistance to flux modulation, right up to the point where the l causes demagnetization, and from what I've read about the TAD vs. JBL, it's why the power compression is so significant in the TAD?
I want to believe that you can get by with neo and ferrite, but for the best, cost no object designs, why are the four-figure drivers still using the alnico? Can it really be only because the salesman said so, and the built-in profit potential from re-magnetization routines allows what amounts to a second purchase of the same item? Like Hendrix with his paper coiled Lowthers, if you have the money...?
I think in a full-range context, alnico has an advantage in its ability to render some material at a resolution that ceramic and neo cannot, if it is indeed true that it resists changes in flux density better. Is this refutable?
I theorize dan is more concerned with the large signal, reliability issues that gives ferrite an advantage in reproduction, besides the cost issue, but what I think is being skirted about is whether the magnetic material actually possesses different "speed" in its field strength recoveries, for lack of a proper definition, or that it's possible to move a mass back and forth within a field, that staticly is identical, but once it's being pushed against, isn't the same?
You can't use the Lowther analogy either, because the reason they do sound differently is based on differing motor strengths, as well as additional cobalt alloys used in the pole and field, I guess the same is true with the GOTO stuff, and even the Gauss brands.
I know the force is applied through the pole and plate steel, but perhaps the "speed" is really because the alnico motor puts the magnet closer to the gap, and the distance between the pole and the field is where the "speed" is lost, in the steel's return path, or not...
is the steel being saturated in the pole plate in alnico designs from putting the gap closer to the magnet, for the same amount of force, as a ferrite ring will be further from the gap, based simply on magnetic density requirements needed to optimize the magnetic potentials, and the accompanying steel return path in a ferrite design will be longer, allowing inconsistencies in the steel to have a greater effect? Somebody say this is patently false, right? If this were true, the neo-radial design that puts the magnet in direct contact with the gap, would be the "best", but apparently that isn't so either because of the extremely long steel return path?
I guess what I don't understand, is this "coercivity" definition, as it's being used.
I understand coercivity to be the resistive ability of a magnetic material to changes in permanent strength, and not the resistance to "coersion, or coercive force" of the l to overpower b, is this right?
In other words, the field that ferrite produces is easier to temporarily modulate than the field alnico produces, given the same strength, but as you go up in power, the ferrite's field easily reverses, but the alnico won't, once it reaches that knee of temporary/permanent?
and another thing, this alnico/tube relationship, is based on the fact that as a low power tube has poor damping, maybe the alnico's greater resistance to flux modulation is a reason why people like the sound? In that using alnico is simply like adding damping factor to the amp? Or why field coils sound so nice, because they have a constant and unchanging source of emf?
for that matter, is alnico "slower" than field coils? and do field coils have the strength to stay saturated in lieu of 3 kilowatt inputs?
I imagine that would have to be quite a field coil...
I love this stuff.
Oh, and hello, everyone, where's my manners...
MaVo said:
this is specifically what I have a problem with. If you could produce identical drivers, (which I don't see as completely possible, because the material itself has to conform to differing dimensional criteria) I am guessing that there will be a quantifiable, measurable difference in sound, perhaps something FFT or spectral decay plots would reveal, or something....
you would have to take it further to reduce differences in mass-caused basket decay rate changes, and for waveform reflection, aerodynamics, and helmholtz changes, add to the neo and alnico, such that the shape of the motor is identical to the ferrite, and the mass behind the magnet is also the same, if that's a possibility-
then we might have truer apples to apples,
anyone?
and MaVo, I think you are using audiophile in the derogative, is that possible?
I don't have "equivalent" speakers for comparison but when I switched from D140 to E140 for bass guitar with Traynor push-pull tube amp, lost some "bounce" and felt the ferrite had a "hard" sound - - nothing was controlled but that was the impression. A similar impression came from updating the power supply capaictors in the Traynor and was suggested a small inductor in series with the main filter might emulate the old cap.
I think alnico 416 have a softer treble attack than 421 ferrite but again these aren't fair comparisons
high -end horn loudspeaker designers seem to favor fiield coil motors.
in old age I want things light and simple :^)
I think alnico 416 have a softer treble attack than 421 ferrite but again these aren't fair comparisons
high -end horn loudspeaker designers seem to favor fiield coil motors.
in old age I want things light and simple :^)
Because it cools the voice coil
But as others have mentioned, you have to consider how it is used ... PA, loud HIFI or with low power amps ... I know that TADs are used for studioPA, but others like PHY, Lowther, Supravox are often used with small tubeamps ... and just fore the record, I think some of the VERY expencive GOTO are rated at 5watt
But as others have mentioned, you have to consider how it is used ... PA, loud HIFI or with low power amps ... I know that TADs are used for studioPA, but others like PHY, Lowther, Supravox are often used with small tubeamps ... and just fore the record, I think some of the VERY expencive GOTO are rated at 5watt
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.