No, in motors application the wire is used as a coil and cannot have imperfection either in soldering sections or in the surface : it will cause corona and burn through the insulation. It is critical in this application to know the correct inductance and resistance to some extent of the annealed copper.
What I mean is that there is a difference when you measure through a specialized gear designed to measure cable resistance and a garage voltmeter. This is serious enough in the motor industry that the customers require those tests and cannot accept a garage or electronic bench ohm reader.
I think that testing the wires for higher frequencies with a scope could enable discontinuities detection and bring to a higher standard the amplifier manufacturing.
Ah, ok, I see what you were saying.
However, that model is simply a local lumped element of an infinitely long system. It is truly terminated, just by lots and lots of those models.
Any signal propagating along that line will have exactly the same amount of energy stored in it's inductance as it's capacitance. That is actually the true definition of a transmission line.
E =1/2 L I^2
E = 1/2 C V^2
1/2 L I^2 = 1/2 C V^2
LI^2 = CV^2
L/C = V^2/I^2
L/C = (V/I)^2
sqr(L/C) = V/I
As long as there are no reflections, this relation always holds true. When reflections occur, such as a 100 ohm line hitting an 8 ohm load, the line will begin to charge and the inductive energy storage will rise up consistent with the load's current requirement at the voltage.
For loads of a Z less than the cable, the cable's inductance dominates.
For loads with Z higher than the cable, the cable's capacitance dominates. That is why a line impedance matched zobel at the end of a very low Z cable is needed to prevent amplifier oscillation, when the load "unloads" at very high frequency, a "hot" amplifier will see a capacitance dominated cable.
jn
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Also, tell that to Demian. I noted he mentioned using cables of 8 ohm impedance, and he said it sounded different.
But nobody discussed that statement.
Jn
8 Ohm requires about six parallel 50R cables, so about 630pF/m. A few meters of that and many amplifiers will burn.
I do not beleive it is any better than 2 x 2.5mm2 speaker cable at a cost of $10 for 10 meter. I beleive in placebo effect and happiness at owning expensive stuff.
IMO, low resistance is all that matters.
Sorry a crude attempt at showing why the characteristic impedance from the standard formulation at low frequency does not really figure.
The VERY long line with any loss also never sees the end because all the energy is dissipated.
Only if it's unloaded at the far end. If it's terminated with the proper load, the amplifier will not see the capacitance.
jn
I was referring to this:
Perhaps I took this out of some other context? If so, sorry bout that.
jn
Perhaps I took this out of some other context? If so, sorry bout that.
jn
Most amplifier HF oscillations are above the audio frequency range. I am not saying that L and C don't matter, but in the audio frequency range by far the biggest issue is R. At somewhat higher frequencies when L begins to dominate over R the speaker cable usually starts to look like a poorly terminated transmission line, and typically the amplifier then sees the C.scott wurcer said:
We do.
Used for outdoor deck planks, typically.
We also like the Phillips.
And Torx.
And the TA, the Quadrex and the cute little pentalobe.
That you don't remember or even need to know inches, feet, yards and miles is of very little concern to me: I live in a country where these are the common man's standard for 315,000,000 people. That Europe once had nearly 175 linear measure units (BM: before Metric) is indicative of how provocative the idea of Metric Unification was to the Old Country. Europe - and by proxy, the situation in the rest of the world equally - was reforming from over 175 mutually incompatible and nearly arbitrary local units of measure to one system of (nearly) agreed standardization and authority.
Oh, for the sake of The Big Countries, some of the chosen metric measures were conveniently close to the National measures at times. But mostly, it was the grand unification afforded by science to science, technology and the common man alike that was so attractive. We - in America - having frankly a relatively easy system, and one already unifying the entire country, didn't see such a compelling reason to go to Metric wholesale.
In fact, we even tried! Our milk jugs are in milliliters and ounces/gallons. Our boxes of crackers, cereals, sugar and chocolate dust are in grams and ounces/lbs. Once our roads had bigger kilometer measures next to smaller mile-measures. This was rather slapstick, so after 20 years we slowly began to remove all those and revert back to miles, quarter miles and half miles. We never reformed our land-area measure, because we have (and had) only one unit: the acre. It continues to hold firmly in the lead against the hectare.
Remember that Europe had at least 28 units of area for land measure. And land-area remains one of the last holdouts against metrication. Largely I guess because once the land is divvied up into units an old Dead King ratified, the civic system isn't going to redraw all those borders and deeds of ownership.
IT IS OK, FRIEND. We need not agree. And since you mustn't have read my entire round of comments, I am a practicing scientist and use Metric all the time. MKS metric, I must confess. I'm happier with joules than ergs, meters and millimeters without centimeters and dekameters. Since my sciences are chemistry, electrical/electronic engineering and computer science, I can take-of-leave kilograms vs grams. Either is fine. And when I purchase bread flour its in lbs. Just as when I buy lumber, it is in inches and feet.
GoatGuy
I walked into the Boyajian store and asked for a 1cm slice of fois gras and the guy looked at me like I was nuts.
Spooky and terrible OFF Topic !!
When I was a child I thought that I could see the world united and without wars...
I fed that utopia that my father would have explained to me that there was a universal language, which would achieve easy communication among all the inhabitants of the earth and would definitely banish the biblical figure of the Tower of Babel ......
It was only necessary that all nations agreed to teach it in their respective schools from the first studies ........
Esperanto - Wikipedia, la enciclopedia libre
Now it's your turn to use the Google Translator, I did not find it in English ......
When I was a child I thought that I could see the world united and without wars...
I fed that utopia that my father would have explained to me that there was a universal language, which would achieve easy communication among all the inhabitants of the earth and would definitely banish the biblical figure of the Tower of Babel ......
It was only necessary that all nations agreed to teach it in their respective schools from the first studies ........
Esperanto - Wikipedia, la enciclopedia libre
Now it's your turn to use the Google Translator, I did not find it in English ......
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The problem is amplifiers that have very high frequency response. With a low impedance cable and a load which decouples at high frequencies, the L does not "dominate", but rather the cable capacitance dominates. When the capacitance dominates, the negative feedback phase margin exceeds 180 degrees, causing positive feedback and oscillation.
This is not a physics thing, it's an engineering thing..
Try to keep up.<==low hanging fruit time...😊
Jn
I've been gluing up hardwoods for my clock gears...veneers are 1/28th inch?? Or, was it 1/20th inch?? Where do they get these numbers???
Jn
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