Like get no credit, my EE102 instructor said after the midterm yes your answer to the problem was correct but it's not the one I wanted. He then said the sooner you learn what MIT is all about the better. Literally in those words.
Years later I was taking a grad course in microwave electronics and 1/3 of the final was a very complicated flow diagram question. No one not even the professor realized that you could write down the solution by inspection simply using conservation of energy. I won that one, you can't argue with mother nature.
That's MIT for you. It is just like the English Prep Schools that would teach someone 'proper' English usage. They could spend the rest of their lives correcting everyone that they met outside their culture, but it would just be as insulting and wasteful as what is done here. We all know what DC resistance means. It means the impedance that you measure at DC. This separates the resistive component from any added impedance, either inductance, capacitance, or MOTIONAL FEEDBACK from the wire resistance in the voice coil of a specific direct radiator speaker. Quibbling between DC resistance and DC impedance in this case actually just slows down communication.
Unless you want to get into something juicy like the heat produced from a DC 5.6ohm VC.
It can be that way in other schools, at work with the boss, in other life situations, etc.
Fair or unfair if you give an answer that somebody with power over you doesn't want to hear, it can get you into trouble. However, I still don't see anything unfair about pointing that that people can't communicate very well without some shared language. If there is already some easy-enough-to-learn, standardized, well-established language for something it wouldn't usually make a whole lot of sense to invent something new to do same thing only less well.
The point of accurate definitions and rigorous rules is to avoid communication errors and thinking errors. Some may find this inconvenient. To professionals it is essential and expected.
Not that these standards are required in DIYaudio...better here to be more flexible for inclusiveness.
Not that these standards are required in DIYaudio...better here to be more flexible for inclusiveness.
Again, the eddy losses in the vc wire are frequency dependent. The wire resistance at frequency changes.
The eddy losses are considered resistive as well, however is comprised of two components...losses directly in phase with the fundamental, and a distorted eddy loss component that is as 2F.
The magfield stuff is easy. What I really would like to discuss is how the amplifiers handle four quadrant operation. Also, how the opposite rail elements need to conduct for hf in the midst of lots of lf content.
jn
I for one always look forwards to the view from the sledgehammer* factory as JN reminds of what sweating the details really means.
*As far as using sledgehammers to crack walnuts the sledgehammers don't get much bigger and the walnuts much smaller.
Are the detailed complications necessary at this point? What do you think this means?
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I went to a less prestigious university for undergrad and a top flight for grad school (why they let me in, we'll never know) and had that hammered into me early, too. And I'm much younger so it's not even necessarily an era/cultural thing. Heck, in a few classes I lost more credit for not following conventions than I did for getting the wrong answer outright.
But it's not about which school or what, it's about following a certain set of conventions in order to communicate with others. We don't try to talk in highly stylized, poetic form for regular conversation, no matter how lovely it is. I was reminded time and again that if one person doesn't understand what I write, it's on that person; if a lot of people don't understand what I write, it's on me.
I'm just waiting for Ed to talk about how we shouldn't use Ohm's law for speaker impedance. 😉
Me too, I found this at the top of a search BTW. Time, temp, etc. invariant R, L, and C are useful constructs to teach basic theory and (in general) make first order sense of what's going on. Considering wire wound resistors were common and many common pure metals have resistivity roughly proportional to absolute temperature (3000ppm) I find it hard to believe that this was missed in Ohm's time.
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I applaud schools for teaching more in depth topics than found commonly - in fact I think it was the reason we formed higher education. Frankly I feel like my education was well too expensive for what I got. When I bring up subjects that the adjuncts or professors have to change topics on, as to not lose the rest of the class, that's a huge disfavor to me. In retrospect I should have challenged them more and requested some kind of balance of credits to education offerings, within individual subjects, with the intention of reimbursement for successful challenges. That should be the new thing...
Anyways, where it gets annoying is when the exercise of knowledge is anything "proper" or driven by opinion is simply done so to be egotistical. What is well known in the education system & professional world for writing is that there is a limit to how tactfully the complication of structure & word choice can go, for a given audience. Where as scientists seem to subconsciously prefer to make language diverge from commonality like it's a competition for who is more scientific.
I hear this quite often from concerned potential customers about the switch in comparing A/B amps to A amps. It's as if a Leprechaun has a meter and his hand on a big knife switch.
"How many angels can dance on the head of a pin?" Is considered by most to be an example of a totally useless debate.
"Does a violin sound"... is an example of reality, there are factors beyond reasonable control that set limits.
Absolute truth is a philosophical construct. Nothing in reality is an absolute, not even statements.
What Ohm wrote and how it is perceived today is not an absolute.
How accurate does the model of a loudspeaker need to be?
What is the output impedance of a thermionic amplifier? Of a bipolar transistor high feedback design?
Extra point question how does feedback affect a thermionic audio amplifier?
"Does a violin sound"... is an example of reality, there are factors beyond reasonable control that set limits.
Absolute truth is a philosophical construct. Nothing in reality is an absolute, not even statements.
What Ohm wrote and how it is perceived today is not an absolute.
How accurate does the model of a loudspeaker need to be?
What is the output impedance of a thermionic amplifier? Of a bipolar transistor high feedback design?
Extra point question how does feedback affect a thermionic audio amplifier?
I thought it was a troll! Have I been wrong all this time? (Yes a straight line. Best response wins a prize!)
I figured it was Maxwell's demon doing OT. We have a state trooper crisis here on the overtime issue, once it became public there were folks making $250K plus directing traffic at the airport on their spare time they cut it off and now the traffic can be chaos.
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