If you came to me and said "I just put electro-magnetic shocks on my Porche and it handles better than any Porche I've ever driven." I might say "Cool! Sounds like fun, wish I could try one." But I might also ask if you've taken it around the track and timed it against the standard shocks. If you haven't - I might remain skeptical.
On the other hand, if you had taken it 'round the turns and timed it against standard technology, I'd be thrilled. Nothing wrong with an A/B test to see if there really is a difference and how much. Maybe you're onto something great.
So why is there such a reluctance to A/B a field-coil driver and a PM driver, all else equal? It would be a great way to know what the differences are. What's wrong with that?
On the other hand, if you had taken it 'round the turns and timed it against standard technology, I'd be thrilled. Nothing wrong with an A/B test to see if there really is a difference and how much. Maybe you're onto something great.
So why is there such a reluctance to A/B a field-coil driver and a PM driver, all else equal? It would be a great way to know what the differences are. What's wrong with that?
it seems to me that problem is when someone is forcing someone ........ , not in potential DBT .
on internet behavior comes before knowledge ;
with wrong behavior communication is impossible
on internet behavior comes before knowledge ;
with wrong behavior communication is impossible
I guess he has to do something between Rush Limbaugh reruns...
I appreciate Speaker Dave, on the other hand. He is a skeptic and looking for proof but I sense a thirst for knowledge...not a thirst for blood. Talking to knowledgeable skeptics is a useful learning tool.
Fighting off objectivist thugs is not a learning experience. It is more like being in a zombie movie, where the ghouls keep coming at you and you have to whack them in the head with a bat to get them out of the way so you can get to your car.
I for one would love to do comparisons between the same driver in PM and FC. I'd skip the scientistic DBT overlay but this would be very instructive to do.
The problem with testing is that the test does not reproduce the conditions of normal use. We don't listen to music with the ear sharply dialed in to her differences or trying to "beat" a DBT.
I learned the new audio term of "sighted belief systems" here, i.e. Looking at a speaker frames how you are going to hear it. We see the curtain, the Harman employee in a lab coat Now what effect is that sight going to have on our hearing?
There is actually a large body of research on the visual biases in Western Civilization, but the objectivist thugs avail themselves of none of it, of course.
I've participated and staged many A-B tests. One problem is that a test looking for differences tends to valorize certain effects...etched sound, presence peaks etc. that make sound stand out. The bright nasty tweeter sounds more different, hence better, while listening to Scottish Fantasia using it would make your ears bleed.
But the main blow to the formal test is this: Music is meaningful sound. It is not a sine wave hearing test at the Army induction center. Meaning always depends on context and DBT destroys the music listening context. Evaluation must be conducted in a way that tries to preserve the music experience.
Tests are thought to work because they set up a controlled experience outside of normal life...well, this is precisely what kills them and renders them beside the point.
I can't think of any field coil fan who would turn down an opportunity to compare a PM and FC of the same driver--the closer matched except for magnet, the better.
I know folks like Fabio and myself would also like to see measurements, if we could figure out what to measure, and I think we are indeed looking for a "solid" technical explanation.
But we are both experienced listeners and we are not going to reject our listening data as "conjecture" because we don't have numbers to back up what we hear.
That is crazy talk....especially when coming from people who don't have relevant listening experience and seem to be looking for excuses to avoid it.
I try to add something.
It's obvious that we all have different tastes. So "better sound" has no meaning from many points of view. A/B tests have the problems Joe told us. I confirm from direct experience.
I never look for "better sound" but I always look always for differences. I mean that: the more difference between discs I hear the better the system is.
Try to think about it. I don't know if all you guys ever tried it in this way. Maybe yes.
I have thousands of discs. I take a few of them, discs with clearly different masters.
I listen to them. The system showing more differences is the best. No matter the taste, no matter the feeling. That system is more neutral, if I can say so.
I hope my english was clear enough.
It's obvious that we all have different tastes. So "better sound" has no meaning from many points of view. A/B tests have the problems Joe told us. I confirm from direct experience.
I never look for "better sound" but I always look always for differences. I mean that: the more difference between discs I hear the better the system is.
Try to think about it. I don't know if all you guys ever tried it in this way. Maybe yes.
I have thousands of discs. I take a few of them, discs with clearly different masters.
I listen to them. The system showing more differences is the best. No matter the taste, no matter the feeling. That system is more neutral, if I can say so.
I hope my english was clear enough.
Let us distinguish between trolls who act out of sense of intellectual conviction, even if they are stupid as a rock, and trolls who are in it for the blood sport, looking for a new pastime since the Klan was kicked out of the county.
My concept of science, or empirically based learning, is that the proper scholar adjusts his preconceptions in accordance with experience.
A scientist will say, "Damn! There should be no differences between these power cords but I can hear a difference. WTF!? I have to figure this out." Always open to revision and refinement.
This is why the very definitions of science have changed since the Benny Goodman days that DavidL lives in. Experience exposed chinks in the accepted theory so they adjusted the theory. This is key to learning and growth of knowledge and understanding
The religious zealot won't let experience get in the way of foundational beliefs or will find some crazed twisted way to phrase things to preserve that belief.
Rush will always find a way to criticize liberals and come up with arguments to convince himself that munching pharmaceuticals and going on sex tours of the islands to hire underage hookers is totally justified.
The king troll on this thread won't even discuss. He comes in with a demand that you provide the numerical data he wants on his terms or else go away. Who needs this? Where is the bozo filter?
I always hope that the technically knowledgeable naysayers might give up some information and perspective that will help me refine my understanding. Surely people who don't "believe in" field coils know things about speakers that can helps us all sharpen our thinking on the issues.
Racheting the discussion up to an issue of scientific epistemology then trying to shut it down based on the moral primacy of discredited (or at least arguable) notions is dysfunctional behavior and interferes with our learning.
I have not seen convincing empirical arguments on why field coils sound better. But if they do sound better or even different, then there must be some mechanism behind it other than the mental delusions of the listener.
I don't think we will answer this question here but we can try to make steps forward.
My concept of science, or empirically based learning, is that the proper scholar adjusts his preconceptions in accordance with experience.
A scientist will say, "Damn! There should be no differences between these power cords but I can hear a difference. WTF!? I have to figure this out." Always open to revision and refinement.
This is why the very definitions of science have changed since the Benny Goodman days that DavidL lives in. Experience exposed chinks in the accepted theory so they adjusted the theory. This is key to learning and growth of knowledge and understanding
The religious zealot won't let experience get in the way of foundational beliefs or will find some crazed twisted way to phrase things to preserve that belief.
Rush will always find a way to criticize liberals and come up with arguments to convince himself that munching pharmaceuticals and going on sex tours of the islands to hire underage hookers is totally justified.
The king troll on this thread won't even discuss. He comes in with a demand that you provide the numerical data he wants on his terms or else go away. Who needs this? Where is the bozo filter?
I always hope that the technically knowledgeable naysayers might give up some information and perspective that will help me refine my understanding. Surely people who don't "believe in" field coils know things about speakers that can helps us all sharpen our thinking on the issues.
Racheting the discussion up to an issue of scientific epistemology then trying to shut it down based on the moral primacy of discredited (or at least arguable) notions is dysfunctional behavior and interferes with our learning.
I have not seen convincing empirical arguments on why field coils sound better. But if they do sound better or even different, then there must be some mechanism behind it other than the mental delusions of the listener.
I don't think we will answer this question here but we can try to make steps forward.
Hi fabcam. Keeping it one technique in the toolkit might be safer. If I'm not mistaken, recent research revealed the ear integrates short delay reflections to extract extra information it would miss under anechoic conditions. In practical terms, placing speakers too near a side wall for example allows a listener to hear more details – any maybe differences - independent of the obvious negative impacts on accuracy otherwise.
I don't know if this is relevant to PM vs FC ( probably not ),
but my own very subjective "test procedure" is like this:
If I just have to listen to another record before I go to sleep in the evening, it's good.
If I have no problem turning everything off and go to sleep, something is wrong.
As I said, very subjective.
And the good/wrong have nothing to do with sound quality, as such.
I don't know what it is.
And no, I'm not one of those cable/tweak persons either.
ok, sorry for OT, back to the PM vs FC discussion....🙂
but my own very subjective "test procedure" is like this:
If I just have to listen to another record before I go to sleep in the evening, it's good.
If I have no problem turning everything off and go to sleep, something is wrong.
As I said, very subjective.
And the good/wrong have nothing to do with sound quality, as such.
I don't know what it is.
And no, I'm not one of those cable/tweak persons either.
ok, sorry for OT, back to the PM vs FC discussion....🙂
Here's a relevant article from my favorite science journal, Stereophile
Hot Stuff: Loudspeaker Voice-Coil Temperatures | Stereophile.com
There is some good stuff to think about in that piece.
------------
Heating is a physical effect that might come into play with field coils. I never thought about that before but it is rolling around in my mind.
One way to look at a field coil is as a temperature stabilizer like a crystal oven. The coil dissipates a constant I sqr R loss as heat. The heat capacity of the coil and the massive iron structures, you see on most field coils keeps the driver environment free of sudden or transient temp deltas.
OK, but what effects does this have...on voice coil behavior, magnetic system? Maybe none, but it worth mulling over for a bit.
Well let me throw out an idea and suggest an experiment for the intrepid DIYer interested in this topic. Earlier in this thread, I posted a link to a small vendor who does field coil conversions of older Altec drivers. While the data from that vendor was dismissed out of hand by some, I thought it was interesting. The data presented by CH Audio, seemed to show that the signal applied to a speaker's voice coil modulates the magnetic field in the speaker. This isn't really surprising if one thinks about it.
Speakers aren't 100% efficient - only a small amount of the energy we put into the terminals of a speaker make it out as sound. The rest gets converted to heat and probably ends up heating up the voice coil and associated magnetic structure. It's reasonably well known in the scientific literature that the magnetic properties of a material are temperature dependent. This means that as we play music, we also heat up the speaker and thus its characteristics are changing dynamically. This is a form of distortion that I can imagine is audible.
Now a field coil speaker will be different in two ways. First, it's using an electromagnetic which should not be temperature dependent. Second, even if there are temperature effects, it's also heating up the speaker and essentially created a controlled temperature environment that is less susceptible to temperature modulation effects from the applied signal.
So here's my suggestion for an experiment. If temperature effects are at least partly responsible for the improved sound from field coil speakers, then one should be able to improve the sound or at least change it by heating a conventional driver independently so that the temperature is controlled by an external heater and not the applied signal. A quick scan of McMaster Carr shows that they sell heating tapes that should work although temperature control would be something that would need to be worked out.
Now if I had all the time in the world, I'd try this myself, but I barely have time for much simpler DIY work. So I'll have to leave the rest of this exercise to the reader.
---Gary
But then you would be heating an alloy magnet of possibly different heat-dependent qualities than an electromagnet where the metal part of the magnetic circuit is usually iron or iron alloyed with hi-perm elements.
Are there any known first order effects of heating ferrite, AlNiCo, or neodym on the scale we are talking about?
Although it would be difficult to do evenly, perhaps cooling an electromagnetic driver down to ambient temperature would provide a more instructive data contrast set.
Alnico don't handle heat very well, as far as I know.
The heat has always been my major objection to FC,
but maybe a water-cooled FC would be cool?
Not that it would make everything complicated, or anything.
And with the guru's telling us the FC power supply is a major deal .....
The heat has always been my major objection to FC,
but maybe a water-cooled FC would be cool?
Not that it would make everything complicated, or anything.
And with the guru's telling us the FC power supply is a major deal .....
Hows that?? Seems the original Alnico would be a better choice for heat dissipation. At least the original pot starts at room temperature. Not only that but the quickest heat loss is going to be through the coolest structure not the hottest. So when the transients come in the pot's already warm so if anything you are actually getting the VC hotter and keeping it there for a longer period of time.
Maybe you should read this: JBL Technical Notes Volume 1 Number 9
Alnico's fine it's Neo and Ferrite that have the issue with heat
http://www.audioheritage.org/vbulletin/showthread.php?4031-The-Great-Alnico-Ferrite-Debate
Rob🙂
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Related to the subject of magnetic flux modulation by applied signal...
This is the area which seeems most promising to search for clues.
What are the recovery characteristics of magnetic materials vs electromagnets? A field coil has a stable external power source, rather than depending on inherent magnetic potential. Does this reduce the instability of the system?
I have seen studies on this phenomenon. Alnico had better restoration behavior than ferrite but electromagnet was the best.
Does anybody remember this? I should have kept the info but I didn't.
This is the area which seeems most promising to search for clues.
What are the recovery characteristics of magnetic materials vs electromagnets? A field coil has a stable external power source, rather than depending on inherent magnetic potential. Does this reduce the instability of the system?
I have seen studies on this phenomenon. Alnico had better restoration behavior than ferrite but electromagnet was the best.
Does anybody remember this? I should have kept the info but I didn't.
The principle of a crystal oven is partially reliant on the fact you point out that thermal transfer slows at higher temperatures, creating a steady state environment.
By raising the temperature and keeping it there, the oven creates an environment where local changes within the system are a smaller % change.
According to Fourier's equation for thermal conductivity:
K= 1 Btu/(hr oF ft2/ft)
Conductivity is an inverse function of temperature but it varies an an inverse square of the volume of the mass/unit distance. Hence, size of the heatsink is the predominant factor.
The relevant question here is whether the flux modulation that heat causes if any would be more to a change in absolute temperature or as a change in percentage of system temperature.
In crystal ovens, stability is defined as a percentage change in the accuracy of the crystal to target frequency. This might be a different problematic.
I am sure this kind of data is out there somewhere. I haven't done the magnetic materials research so anything I am thinking is speculation sujbect to verification.
What does an ovenized crystal have to do with loudspeakers?? There are a multitude of reasons to keep a crystal at a fixed operating temperature.
If you run a loudspeaker at an elevated temperature you are artificially moving the average temperature up. That is not something you want to do. All you are doing is decreasing the power handling on the driver and pushing it closer to power compression at the same time.
Crystals and heat are good for each other loudspeakers and heat are not.
Rob🙂
Do we fully understand the effect of heating and how it effects different magnetic materials and speaker driver systems as a whole?
Maybe moderate heating to maintain a constant T is a good thing or not a bad thing. Maybe does nothing. Maybe heat is a lot worse with permanent mags than electromags and the 'ovenizing' feature is epiphenomenal.
Maybe inconsistant heating under transient condition of certain areas of a magnet more than others, before the heat has time to spread out through the mass, is a problem. Does having hotspots mess up a magnet's performance properties?
In practice, field coils do not get that hot. Power transformers can run a lot hotter within spec.
Frying voice coils with excessive dissipation is never a good plan but this might more more subtle than that.
Who knows the physics?...yo, help me out propeller heads! I dropped out of physics at Penn and became an anthropologist instead.
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