No. That is, I don't think you are saying what you are trying to say sensibly yet.
Does back EMF impedance = V * Z? You say there is back EMF and coil resistance. So, you have a V and an R. And you say there is the speaker current I. So, R/I = V? Still V isn't turning into R and coming out in ohms. Can you please try to explain in the above terms, since you say you are trying to work out the math. I think you need to keep thinking it through until you can explain it in the above terms. Everyone has to learn how to do this stuff in physics 101. It's half the credit on every problem. Just getting the numbers right doesn't mean you really understand it.
EDIT: Or maybe the problem is that you mean there is reduction in current arising from the presence of back EMF. Something like that? It still wouldn't make EMF an impedance though.
EDIT 2: Maybe you could draw it as a lumped equivalent model. Show the impedance like a resistor and the back emf like a voltage source. What would that look like?
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Markw4, you make more of it than it should be. First, it is relatively easy to measure the impedance curve of a loudspeaker, AND it can be explained as resistance, a low frequency resonance, and inductance (at high frequencies). Of course what we measure is a combination of the bulk resistance of the voice coil with a back EMF generated by the movement of the speaker that is acting as a generator which increases the impedance measurement at some frequencies. If anyone really wants to know more about the effects between the speaker and the amp, then study IIM distortion that was significantly researched in the late 1970's and early 1980's. Matti Otala usually was part of these research papers, but there were others as well.
Markw4, I did not mean to imply that YOU often make audio comparisons when high on something, but I was generalizing that MANY here do. It really can make a cheap, relatively lousy system sound pretty good! LSD is the best. On it, I could not tell 'Live from Memorex!' That is why I always do my evaluations both drug and alcohol free. I need to hear the problems, if I am to attempt to fix them.
Markw4, I did not mean to imply that YOU often make audio comparisons when high on something, but I was generalizing that MANY here do. It really can make a cheap, relatively lousy system sound pretty good! LSD is the best. On it, I could not tell 'Live from Memorex!' That is why I always do my evaluations both drug and alcohol free. I need to hear the problems, if I am to attempt to fix them.
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Right, John. I get that back emf makes the net voltage higher while current is still about the same, so impedance looks higher. But, that doesn't make the back EMF into an impedance. Its the changing voltage part of the equation.
It looks like Joe has an intuition about this, and the math is remaining elusive. No wonder, the intuition is a little bit off and if some logical reasoning can straighten out the rest of the thought, then the math should drop out pretty easily (I would expect).
Maybe you can help Joe with this. If so, it would probably helpful all the way around. Helpful to Joe and helpful to engineers that he wants to talk to about it since then they won't say, nonsense, not even wrong, hilarious, etc. Not that they should say such things at all in such cases, but the fact is they often do.
It looks like Joe has an intuition about this, and the math is remaining elusive. No wonder, the intuition is a little bit off and if some logical reasoning can straighten out the rest of the thought, then the math should drop out pretty easily (I would expect).
Maybe you can help Joe with this. If so, it would probably helpful all the way around. Helpful to Joe and helpful to engineers that he wants to talk to about it since then they won't say, nonsense, not even wrong, hilarious, etc. Not that they should say such things at all in such cases, but the fact is they often do.
For consumer mid-fi, yes as in subtle but recognisable.
Try a few AB experiments and take a close listen.
Dan.
There you go Mark, this is not that difficult to understand, maybe just a bit harder to explain. It is not even a claim.
But what is a claim is how this can affect the harmonic distortion of the driver and make it worse, this is what we are working on. And if correct, there should be correlation between what is measured as current distortion on the current side of the voltage amplifier (keep in mind that the amp can only 'fix' the voltage and has to relinquish the current to the load as indicated by the impedance graph and the current phase angle).
I have figured out how to do this and consulted others about the method. What I have shown from the amplitude variations caused by the back-EMF means that that imperfections of the driver, all of them will show up modulating the back-EMF impedance, hence modulating the current of the amplifier. We already have some evidence of this.
We know that the harmonic distortion of the driver can be measured mirrored in the current that the amplifier. So the next steps is various distortion measurements on both the electrical side and the acoustic side of the amplifier. Takes a bit of effort to do those distortion measurements and that will tell us if the theory stands up. And I haven't even told you exactly what that theory is. But all previous amplitude measurement done with that equivalent test indicates something potentially powerful - that you can reduce the final degree of harmonic distortion heard through the speaker/driver, something measurable, cause and effect. Please note, I am choosing my words very carefully, I did not say reduce the harmonic distortion of the driver. We shall see.
Yep. I have Esa Merlainen's book and he says the same thing. This is not a claim, it is how it works, right?
I am aware that you and Otala had an interesting relationship, ahem. Quite a few years ago I went to see my Danish/Norwegian brother who lives 100Km from Oslo (I am Danish/Australian). He took me into Oslo and we met up with Per Abrahamsen (Electrocompaniet) - I ended up talking with him for a couple of hours, about Otala and more. It was some time is the 80's. Much of the discussion was also about the nature of feedback - it certainly was a ripe topic at the time. Has it ever cooled down?
What I have been trying to explain here, but being a bit coy I admit because of the monkey-howlers that frequent here (know what I mean?) is that there may be something of a surprise looming. It won't mean that we need to change amplifiers, but certainly if proven, it will affect those who design loudspeakers. And it has to do with the current rather more than voltage (no, I pre-empt, voltage is not the enemy here.
Let me say something that might get some people revving:
1. The voltage of an amplifier tells us what we ought to be hearing, the current of the amplifier is what we are actually listening to.
I have now put that phrase past a few luminaries (they are the ones I consider smarter than myself) and it has been accepted. Probably not here.
The other one goes like this:
2. There is no such thing as reactive loads, only reactive current.
Guess who actually showed this? A Neville Thiele about six decades ago. Of Thiele-Small fame. Drive any load from a current source (the way he would measure impedance was constant current, aka a current source) and there is no reactive current, no matter how 'reactive' the load might be. They can only become 'reactive' with a voltage source, now we get reactive current.
These are clues. Those two things have now led to a possible way of lowering harmonic distortion we hear in loudspeakers when connected to a voltage source. And this has to be measured. Only actual distortion measurements will be the final proof. It will be proven true or false, but indications so far are good. A mechanism that can be explained.
So John, you power amp designs are safe. Speaker designers will need to pay heed. That's a theory partly proven so far.
PS: My brother owned "The Otala Amplifier" as it was known at that time, a "hot" product!
In Rangiroa (French Polynesia), somebody showed me a CD with zillions of pin sized holes in the aluminum layer I could see through it. One month was all it took for the saltiness in the air to seep through the plastic and eat away the AL.
Good point, if I can relate this to my question. Except that my speakers have no magnets at all: Quad ESL-57
.Edit/PS
I'm surprised to see AFAIK there's no heated debates on neodymium vs ferrite as in Alinico vs ferrite of old.
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Noted Joe, seems more coherent. It becomes easier to understand what you are trying to convey. However, still difficult to follow when you bring too many points in a single post.
When you clamp a ferrite over the mains and ground wire (ie common mode) you simply raise the HF ground loop impedance and convert some of that into heat energy in the ferrite material. In doing this, you may also divert some of the noise to a different loop path, since the loop path is highly frequency dependent.
You cannot generalize and say ‘ferrites are bad for sonics’ without thinking about what’s actually going on. For my part, I’ve tried a lot of experiments with good quality headphones and ferrite clamps (mains) and on the inputs (RF suppression) and heard absolutely nothing. Funny thing, measured nothing as well.
People complain about ferrites and yet are quite happy to slap a 500 watt SMPSU in the same box as the amplifier. It’s almost certain that the Brnchmark AHB power amp has a ferrite based common mode filter on its mains input and it is highly regarded.
This whole anti-ferrite thing was given wings by Charlie Hansen (RIP) a few years ago. Bit like Myrtle blocks and Bybees - nonsense stuff I am afraid.
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Exactly what happened. For fun, i tried to re-paint the CDs with aluminium painting: No luck, as expected.
Same opinion here. I have ferrites on all my chords. Tried with and out, Found no tangible audible difference. Just, on the contrary that my system was imperceptibly more clear. A feeling, at a level where I do not really care and I will not give my hand to cut.
As I know that those ferrites have no effect at low frequency, and that most of my computers/digital video chords use ferrites, that means very high frequencies, i suppose (never measured) they can carry signals up to 200KHz with no changes. Am-I wrong ?
As I believe the manufacturers of those chords would be happy to save money, getting rid of those ferrites, I think they are useful to filter some high HF parasitic signals ?
This said, like with all those kind of strange tips that comes with no technical explanation, i asked myself the question:
On what analogy did someone construct this idea that ferrites were the evil ?
Alnico is known for loosing more magnetic properties with time than ferrite. And to be more expensive.
Neodymium is lighter, more powerful for the same volume, so, can offer advantages on cooling down the moving coil ... what else ?
Do they react differently in presence of an external magnetic field (the one in the coil) ?
Or are the audible differences that some pretend (not easy to make an instant listening comparison between two magnets producing the same magnetic field in the gap) due to the differences of masses they produce on the speakers assembly, that change both its inertia (instant dynamic) and the resonances of their chassis ?
God almighty, I'd never even start thinking about doing such a thing!!! In my world, SMPS are for computer and instrumentation only.
Thanks for the reminder. A quick search turns up this, and it makes very good sense to me. Even though I knew Charles Hansen by reputation only, I think he had a great way to deal with the unknown.
I don't know, that's why I ask.
But since I have you on line, I have another burning question, off topic of course: I have a couple of mic sitting in my cellar for over a quarter of a century. One is a Telefuken branded Neumann M260-KM56, and the other is a M280-KM84; I know they're worth a fortune, but are they really good enough to be worthy of a refurb? The miniature tubes inside are not easy to come by.
Merci Monsieur le professeur Tournesol.
Thanks, but we were not all made by robots and hence we are not robot. Vive la difference.
On the topic of difference, you should meet my wife, oh boy, she can make my head spin as I can't keep up with the topic changes. Sicilian too!
???
One of the valuable audio designer of this forum made what J.C. call "serious listening" comparisons, in order to choose the best PSU for his last design.
(A big current feedback amp).
IE: instant and long term comparisons, several people opinions, acoustically good dedicated listening room, several "hi end" speakers.
And serious measurements.
Comparisons were made, if I remember well, between a big state of the art linear PSU and several (3) SMPS of different brands (2 regulated, and 1 not).
I trust the hearing accuracy, taste and objectivity of this guy. (He changed his mind about one of his preferences after several days of listening).
Guess what he had chosen for his amp ?
2X Hypex SMPS3kA700
Some can be led to different conclusions, but, as always, beware of generalizations
. Trust your ears, try by yourself, dont let you be influenced by any audiophile fashion.Oh, Lord, YES !!!!!! YES and YES.I don't know, that's why I ask.
But since I have you on line, I have another burning question, off topic of course: I have a couple of mic sitting in my cellar for over a quarter of a century. One is a Telefuken branded Neumann M260-KM56, and the other is a M280-KM84; I know they're worth a fortune, but are they really good enough to be worthy of a refurb? The miniature tubes inside are not easy to come by.
.
Mikes are, in a way, like musical instruments. Those old mikes are both very good devices and all have a unique "character".
We chose them, like diamonds, in recording studios, to sculpt the "character" of the sound we want for a given instrument.
You can improve them by working on their PSU (if any), change the components that can be tired with the best modern ones you can find ...
As long as their caps are in good shape.
I know it is difficult to find new tubes for them, but, if you can, and even on an economical point of view, it will be worth the price: they increase their value with time, like all antiques.
He is not here unfortunately to defend himself. But, sometimes people can hear things that are just not there. Let’s lesve it at that and simply say: there is always a rational explanation.
Thanks to you, now they're in the pipeline of the many many things to do.
I hate it when people say retirement is idleness, or, worse, boredom...
Regarding audible effects of ferrites, I once saw a problem when using a line level stereo mini-TRS cable with a ferrite clamp. The cable was connected between a dac output and a headphone amp input, both of which were powered from the same +-15v supply. It sounded grainy, kind of like high order HD. Replacing the cable with a non-ferrite version fixed the problem. Haven't seen any other problems.
+1
I think that some personalities will tend to start expressing odd believes when they come to the realisation that they seem not be able to keep up with or understand the rational part of the world. They start to feel "outside". The creation of an own defined universe with own rules and realities becomes a very comfortable escape pod. With this new universe, the inventor can be as accredit-able as those in the real world - they become an expert, an equal. It's kind of a defence system so that they can still be in "the grove". And it's a strong armour as it is only the inventor that is the ultimate judge of right and wrong in that realm. It's a really "neat" construct - like a drug addiction. But like a drug addiction I'm sure that between the deep intoxications, the addict suffer remorse and would like to get out of it. But the simplest way is as always - the next fix. Of snake-oil.
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TNT, you really should study the science on the subject how humans perceive reality. As it is, you are just making stuff up which is not informed by a lot known science. To some extent all humans have a very distorted and self-constructed perception of reality, including you (and me, and everyone else). Nothing bad about saying that, its just part of being human.
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