I am not your teacher of physics. But if you are really interested, Feynmans Lectures on Physics are imho one of the best tutorials ever written. And they are sometimes entertaining as well
I don't know; I don't claim to be an expert on ferromagnetic materials, although I once worked for a couple of years with some expert materials scientists.Max Headroom said:
Correctly used, ferrite should not harm the sound of a system. Correct use means either sufficiently low current, or use only as a common-mode filter surrounding both go and return currents.
Magnetic fields have three origins, all relying on special relativity because a magnetic field is simply an electric field seen from the 'wrong' Lorentz frame of reference.
1. electric current (school physics)
2. changing electric field (undergraduate physics)
3. spin of fundamental particles (graduate physics, usually - relativistic QM)
See Feynman or other similar textbooks.
The magnetic properties of iron depend on the spin of fundamental particles, i.e. QM.
From there, IIRC, properties of magnetic materials are somewhat complicated. Magnetic domains in materials give rise to hysteresis, and domains are composed of clumps of molecules.
Max (Dan) picked something complex to use as an example. Sure it can be modeled at various levels. A lot of modeling has been done because of interest in switched mode power magnetics, where there happens to be a lot of money involved.
However, precisely predicting things like harmonic distortion based on modeling of magnetic materials remains rather approximate when compared to our ability to measure and hear various kinds of harmonic distortion.
Very clever, Dan. However, it remains to be seen if what you are working on is equally complicated to model. Also, even if complicated to model, measurements should be possible although you may not have the equipment to do it.
From there, IIRC, properties of magnetic materials are somewhat complicated. Magnetic domains in materials give rise to hysteresis, and domains are composed of clumps of molecules.
Max (Dan) picked something complex to use as an example. Sure it can be modeled at various levels. A lot of modeling has been done because of interest in switched mode power magnetics, where there happens to be a lot of money involved.
However, precisely predicting things like harmonic distortion based on modeling of magnetic materials remains rather approximate when compared to our ability to measure and hear various kinds of harmonic distortion.
Very clever, Dan. However, it remains to be seen if what you are working on is equally complicated to model. Also, even if complicated to model, measurements should be possible although you may not have the equipment to do it.
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Regarding the production of precision machines and devices, spinning something may help, as in precision lens polishing. But, using a lathe is not the only way to do it. It does turn out that hand working, the slow yet very precise ablation or removal of material by hand to shape something, with careful measurement along the way is a brief way of describing how it has been done.
Ummmmmmmmmmmm, yeah, you probably haven't really dug into the software then. It's quite, quite, QUITE capable. But, like any FEM, garbage-in-garbage-out is a killer.
* Not to mention the academic license we just got here wasn't cheap. But this is a pretty specialized piece of software.
Yes. Rigourously the behaviours of the three magnetic classes of materials are all rooted in QM.
Yes, and it takes energy to create or change these alignments and groupings/domains.
Sure, but directly relevant to me at this time.
Of course.
Sure, there are many considerations/parameters to model.
Ferrite filters are of course ferromagnetic, my filters are not ferromagnetic.
I have opportunity to access an HP 6GHz vector analyser if I specify or construct a suitable measurements jig.
Clipon ferrite filters and my filters are exact same form factor, and I want to measure and compare both.
How would one go about such a jig, and what measurements should I be performing ?.
More later on my subjective findings on both filters, this may provide clues about higher order effects going on in both filter cases.
Dan.
I don't think a vector analyzer is going to be helpful at this point. The crux of the problem with respect to your claims as I understand them is that files are changed by where they have been, or the cables they have passed through. In other words, files are changed by their history somehow or other, but the data in the files remains unchanged, the 1's and 0's are unchanged. Yet, if the files contain music data, they sound different when played only depending on their history, and despite no changes in the 1's and 0's.
Please correct me if I am wrong about that, and we can proceed from there.
Please correct me if I am wrong about that, and we can proceed from there.
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In my limited experience with ferrites cores for RFID in the 200KHz range, it seems to me that I could wind enough turns on a core to have effects in the audio range.
If I were to do that and run a 1KHz signal through the winding with harmonics up into the ultrasonic range, I would see the suppression of harmonics.
In reality it would simply be a roll off with frequency, but a poorly designed test would give the false impression that I had made a harmonic suppressor circuit.
If I were to do that and run a 1KHz signal through the winding with harmonics up into the ultrasonic range, I would see the suppression of harmonics.
In reality it would simply be a roll off with frequency, but a poorly designed test would give the false impression that I had made a harmonic suppressor circuit.
Yes, you have the above summation pinned correctly, for stored digital data it does seem that 'history' is somehow 'encoded' or 'baked in'.
I have pairs of files stored on my phone that still retain this subtle difference after 6 months now, but this is a different subject for now.
The measurements I am concerned with for now are in the analogue domain and concern measurement of ferrite filters and my filters when clamped around typical system cables, ie, 3 core power, 2 core power, 2 core speaker, coaxial audio and maybe balanced audio but balanced is of of lesser importance for now.
I am asking suggestions on constructing a suitable jig and suitable measurement protocols for testing the analog properties of existing ferrite filters for starters using the above mentioned HP analyser.
Dan.
If it doesn't already exist, would you mind creating a new thread and posting these two files? I'm sure people are interested in that phenomenon. An ABX test like what Pavel is offering might be interesting.
I have it written somewhere, a phone call will find out.
Mark, I think that the frequencies of interest are well above the audio band, and some backdoor advice says that 6GHz is not high enough and that I might need to be looking at 30GHz+.
My first goal is to get measurements to duplicate data sheets from the cable clipon ferrite filter manufacturers, maybe go much higher F than what they typically quote, repeat for my 'gizmo/goop' form factor duplicate.
As DF96 says, yes, measure impedance, attenuation and intermodulation.
So, I need a jig/box that I can quick connect insert a number of example cable types into, and without or with example clipon filters and emulate 'low' source impedance power and speaker systems and defined source and load impedances systems relating to typical line/phono level .
I have local Uni offer of access to this and other gear for free if I can do it quick and unassisted...if I need to spend other peoples time it's going to cost.
Group effort and collaboration and sharing of data....what do I need re hardware jig/jigs and preprogrammed (usb stick ?) test routines to pull meaningful data to flesh out some interesting higher order effects please ?.
Constant level/type of test signal may not discriminate these secondary effects....I can elaborate on a bunch of subjective evaluations/results to help pin down what to be looking for.
Dan.
. Just a small warning, handling those signals and their coupling into audio cables may be a bit tricky.
Do some research on how to do measurements in that frequency range. There is a pretty wide area for errors of measurement and therefore huge chances for comming up with useless data.
Perhaps you should ask your back door adviser to do the tests. Getting numbers is easy with modern test equipment; getting meaningful measurements at such high frequencies requires significant knowledge and experience. Or you could conclude that your adviser knows little more about RF and microwaves than the average audiophile.Max Headroom said:
Maybe while you are there maybe you could ask the computer science department in the university to investigate your bit-identical files which are the same but different.
At very high frequencies very small dimensional changes would be expected to have large effects. Bending a power cable slightly, coiling, letting a move even a little could be a problem. First thing you might want to do if you have a power cable you think makes an audible difference is to move it a little, bend it in one place, loosely coil it, move another power cable around it a little, plug it into a different power strip, etc. If those things make large audible differences, then maybe very high frequencies might have corresponding wavelengths. That would not mean anything HF was going on still, more likely you would be seeing influences from local high gradient lower frequency fields.
Also, high frequency test equipment usually expects to work with 50 ohm interfaces. You might need to build a set of transformers to make your power cable look like 50 ohms over various frequency bands in order to couple it to the test equipment.
In addition, you will have to somehow account for antenna effects which might be very big if you can succeed in coupling energy into the cable to begin with.
Another issue is that test equipment like that usually is designed to work with 2-ports. Two sets of 2 terminals, two input terminals, and two output. It may be further assumed that two of the terminals, one for input and one for output are intended to act as a common. If your cable could be connected with more than two terminals on each end at a time, you will have to figure out what to do with terminals that are not connected to the test equipment. Decisions with that could have huge effects.
Also, high frequency test equipment usually expects to work with 50 ohm interfaces. You might need to build a set of transformers to make your power cable look like 50 ohms over various frequency bands in order to couple it to the test equipment.
In addition, you will have to somehow account for antenna effects which might be very big if you can succeed in coupling energy into the cable to begin with.
Another issue is that test equipment like that usually is designed to work with 2-ports. Two sets of 2 terminals, two input terminals, and two output. It may be further assumed that two of the terminals, one for input and one for output are intended to act as a common. If your cable could be connected with more than two terminals on each end at a time, you will have to figure out what to do with terminals that are not connected to the test equipment. Decisions with that could have huge effects.
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