Hey JN, we hear so much about you being expert in all things magnetic.
So, if I were to enclose a resistor inside a ceramic tube that has a conductive outer coating and connect both in parallel so as to create a two connection circuit element, what are the mutual field effects of the two currents on each other ?.
While you are at it, could you please explain to me why placing a relatively small amount of a non conductive mixture upon a speaker/headphone magnet assembly changes the dynamic noise floor of that speaker/headphone driver ?.
Thanks in advance,
Dan.
So, if I were to enclose a resistor inside a ceramic tube that has a conductive outer coating and connect both in parallel so as to create a two connection circuit element, what are the mutual field effects of the two currents on each other ?.
While you are at it, could you please explain to me why placing a relatively small amount of a non conductive mixture upon a speaker/headphone magnet assembly changes the dynamic noise floor of that speaker/headphone driver ?.
Thanks in advance,
Dan.
I think you know there are speaker cable producers who say they match their cable characteristic impedance to speaker impedance, which is of course LF 😉.
And these producers emphasize importance of cable impedance matching to speakers 🙂.
No it doesn't; no I didn't.Max Headroom said:
Lots of people talk about characteristic impedance as though it is a known resistance at audio frequencies. Lots of people give the RF approximation [sqrt(L/C)] and falsely claim that this is the definition of characteristic impedance. It isn't the definition at any frequency, and it is only the formula for calculating it at high frequencies; at lower frequencies you have to use the full formula or a different approximation.
I could not remember whether you are one of the people who understand this. I know that many people reading and contributing to this forum do not understand this.
Yes, for LF. For much of the audio frequency band the appropriate approximation is Z = sqrt( R / (j 2 pi f C) ) - which is complex and frequency dependent. For those who might struggle to take a complex square root, the result isPMA said:
Z = sqrt(R/(4 pi f C)) x ( 1 - j ) - which has equal amounts of resistance and capacitive reactance.
I know that. And it is us nuts who ask the weird questions, push the bleeding edge, get shot down when we get it wrong...
And some of us nuts get really defensive when our musings are discussed and discredited by smart people..
My DVC magnetic design is novel, apparently new, and so far, nobody's shot it down. That said, I've absolutely no clue if it would sound better or worse, it would have to be built.
I never take credit for my peers work.
things I am decently good at: (sorry, you asked)
coil winding, by hand and using motion control with ultrasonic welding.
soldering, every process known to man..hydrogen furnaces scare me though.
epoxy impregnation, vacuum and wet process
semiconductor thermal transfer, modelling and testing
TCE modelling and practice, from 600 C to 1.8K
ground loop theory and practice
I have been known to play with magnets of various types😉
yah, I do clock stuff
I have become very good at making 63 tooth wooden gears for my wooden clocks...(yes, it's supposed to be 64.. 🙁 ) using a pin router has a very long learning curve...
sub nanosecond TRR test fixturing, and lots of diode experience, from dice in a waffle pack to 100 mm devices within hockey pucks.
Testing of every semiconductor type known to man in dice and packaged form (up to about 1985).
most of that was from previous employment.
Now I do a lot of motion control and NEC.
Don't doubt it. Know it. I will never be considered for one, some I work with may, but certainly not me.
As you can see, my experience base is a tad wider than clocks and coil winding.
You have always been welcome to ask me anything you want, on site or PM. Despite my possibly giving away something that may have been patentable, I have no problem with non disclosure.
jn
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Indeed. I worked for what at one time was the largest independent media manufacturer in the US, and often think I should have quit making media when it became optical discs, which was nowhere near as close to analog audio as magnetic recording which I loved, although I learned a lot of optical and plasma physics, and vacuum technology which was interesting.
I am amazed by and grateful for the contributions of people here like JC, JN, SW and others who have years of actual experience in their respective fields, what resources! I really hope we can revert to discussing actual, provable and testable technologies and drop the personal issues. Not all asides merit responses...
Cheers!
Howie
I like the Indian rug idea. 30yr. ago I noted at a layout review of a dual op-amp that it looked like an Aztec glyph (similar to Von Daniken's ancient astronaut). I considered it a good luck charm.
Balanced signals make sense, but complete mirror image circuitry does not by itself do anything much for signal fidelity except in circuits with little or no feedback (or possibly poor supply management). When you promote no feedback "works" for audio we have half of the endless pointless discussions covered, though I don't think it can touch wire for closed threads.
No. Experience moreso.. However, I also have the resource of a huuuuge knowledge base. As I told my kids when they were in college, there are no science questions their profs could ask that I cannot answer. But it might take a day or two, more if the person I would ask is on vacation or travel..
edit: sorry, I thought you meant two resistors...my bad..
Current will share depending on the bulk resistance of each. Skinning may occur, but that does depend on the resistivity. If skinning occurs, inductance will drop, but that will max out at a 15 nH per foot decrease, and it will not be measurable by the hobbyist. Also, any current on the ceramic tube will produce zero magnetic field internally.
This is the two resistor answer...
The inductance will go down a bit as you have increased the reluctance path.
the two elements will be attracted to each other by what is called the pinch effect. It's the same effect that causes liquid copper conductors in blast furnaces to neck down. At very high frequencies, the current will attempt to skin within the resistors. The conductivity of the outer jacket would try to confine the field of each resistor independently. All this is quite measureable but it would be not easy if the materials only work in the Ghz range.
Measured dynamic noise floor?
jn
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Similarly when I taught introductory classes in programming. Tried to get students to think through the whole problem and the workflow before touching the computer, where at our level it was purely implementation of simple algorithms. Was rarely successful in getting kids to write everything out, but those that did benefited a ton.
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