As to rate of change how about a tri-wave? No distortion? I still would like to see the radial current flow computed analyticly. Shades of Hawksford.
Another possibility is that due to the random distribution of oxide, etc. it creates noise sidebands.
I tried 120 Ohm line 60ns long. Got 2.5us at 2 Ohms and 70ns at 100 Ohms, but a simple T network of L's and a C (no line) picked at a 20pF per foot number gave almost the same answer save the actual line delay. So a simple network does approximately the same thing, I fail to see the point.
doesn't look that easy to make Cu:Cu2O diodes
The H.P. Friedrichs (AC7ZL) Homepage
but it does point out a new piece of physics to agnst over - the junctions are photovotaic too - clear insulation a no no?
The H.P. Friedrichs (AC7ZL) Homepage
but it does point out a new piece of physics to agnst over - the junctions are photovotaic too - clear insulation a no no?
You do not have to consult me at all. You concurred with an erroneous statment regarding what I have been saying, that being a statement of mine being in contradiction with another. (You noticed the "contradiction")..
You then went on at "length" (.002mm length to be precise)
to describe the equivalent "air time" for such a difference.When it comes to image localization, the numbers that are required within a discussion reach down to the sub 10 microsecond level. Humans have repeatedly demonstrated in published, peered reviewed testing, discernment down to 1.5 to 2 uSec.
I have heard the "head in vice" argument over and over used to counter any argument of system modification of localization parametrics. You have entered that trap.
It is not personal, so my apologies if it was taken that way. What I would hope for however, would be more consideration of the issue, and more benefit of the doubt.
I'm not sure, I'll have to think about it. I wasn't thinking of it as a 2f modulation, but an effect that would occur at the rate of 2f.
The actual skinning within a conductor depends on the rate of change of the current. Since it occurs in both directions of current, the exclusion occurs at twice the frequency. The effective resistance end to end will in fact vary in a timewise fashion because not all the conductor cross section is involved in conduction. It's a normal problem in high frequency transformers as well as rf power conductors.
edit: after thinking a moment, the IR drop should indeed be 3f. I have never heard of this being measured, so wonder if that avenue has a dead end sign associated?? The expectation would be a clean 3f signal even on a large solid conductor, whereas a corroded multistrand should produce noisy 2f. I must research this possibility further..
OTOH, we're worrying about relativistic corrections to a cricket ball.
Actually, I agree with that. While I assist in understanding of the test problems associated with this measurement, I also consider it to be a mosquito bite in the middle of a nuclear explosion.
Tri wave??
I'll check, I think Dr. Sullivan from Dartmouth does so, he does have some good pics and explanations on his site... I believe Howard Johnson included at least a pictorial diagram of the toroidal currents in his current revision of his book at a date after I discussed it on AH..I do not know if attribution is warranted nor justified..it was an internet discussion after all.
Nah. Malcolm got bit by his assumptions, and did not know how to properly test exceedingly low impedance, high slew currents..it's a common enough problem, as most do not have experience in that realm.
That is my expectation. I suspect noise (if any), would track the slew rate, so the noise bursts would be at 2f. I do not know if the non correlated nature of subsequent bursts would change what is measured, that I'd leave to other far better minds..
What point do you fail to see??
That simulation shows that when a 20 foot run of typical zip cord is connected between a perfect amplifier and a speaker which varies it's impedance from 2 ohms to 100 ohms across the audio spectra, there will be a variation of 2.5 microseconds at the speaker terminals. (2.5 being what, 63%, 10 to 90, 50? )
What result is obtained when a real amplifier is connected? Say, a QSC RMX1450. It has a 2 uH inductor in parallel with 5.6 ohms 2W (don't know if it's carbon or wirewound), with a .068 uF connect in series with 6 ohms to ground (two 12 ohm 5 w, assumed ww). I do not know how hard the output node on the output stage is, so cannot help with damping factor..
It will only be slower of course, but how far into the audibility regime does it go? Note that 2.5 uSec is indeed within human capability, I suspect this level is insufficient in normal music content for anybody to hear, but that is a blanket unfounded assertion on my part..
The point is, by lowering the impedance of the speaker line closer to the load mean, it is possible to reduce the time delay span.
Using the t-line model is totally consistent with the RLC model when the lumped parameters are selected correctly...and the more elements, the better the accuracy, tradeoff being model complexity.
The t-line model intuitively shows the zero delay (sans prop) inherent when line to load is matched, and it allows for a trivial use of an excel spreadsheet to calculate any combination of line and load to see delay span.
The t-line model becomes cumbersome when added elements such as amplifier output L/R are added, here your spice t-line or spice lumped will produce fruit.
Cheers, jn
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Just a question. Do-you think people selling those 3000$/m audio cables, believe themselves in their, how do-you call that, "snake oil" ?
Or did they just play in a Michael Jackson & Paul McCartney's video clip ?
It is a stereoscopic analyze. Our tympani is not able to move at more than 20 000 hz (around).
Am-i wrong ?
I believe the way we localize sounds (to protect ourself from predators) is a complex addition of factors, including reflexions, and use slight movements of our head. Our brain design some map of our environment in our short memory. And some models in our long time memory.
Or did they just play in a Michael Jackson & Paul McCartney's video clip ?
..As far it is a *delay* in the fundamental of a sound *between the two ears*. and this fundamental has to be somewhere between, hum, 300- 5000 hz ?
It is a stereoscopic analyze. Our tympani is not able to move at more than 20 000 hz (around).
Am-i wrong ?
I believe the way we localize sounds (to protect ourself from predators) is a complex addition of factors, including reflexions, and use slight movements of our head. Our brain design some map of our environment in our short memory. And some models in our long time memory.
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Also one can consider the length statement presented by Max T as well.
From Scott's analysis, he shows prop delay only when line matches load, and the delay associated with the line/load mismatch.
Lets say, 70 nSec matched, 2.5uSec mismatched at 20 feet using an ideal amplifier.
Lets now use 200 feet of cable.
Matched, 700 nSec delay.
Unmatched, 25 uSec.
Increasing the matched cable length an order of magnitude causes less than a microcsecond delay.
Increasing the unmatched causes a 25 uSec delay, a level I cannot brush of as inaudible across the audio band over 500 hz.
Granted, 200 feet is extreme..however it points out why Max's assertion of length invariance is accurate when the cable impedance is close to the load.
Cheers, John
From Scott's analysis, he shows prop delay only when line matches load, and the delay associated with the line/load mismatch.
Lets say, 70 nSec matched, 2.5uSec mismatched at 20 feet using an ideal amplifier.
Lets now use 200 feet of cable.
Matched, 700 nSec delay.
Unmatched, 25 uSec.
Increasing the matched cable length an order of magnitude causes less than a microcsecond delay.
Increasing the unmatched causes a 25 uSec delay, a level I cannot brush of as inaudible across the audio band over 500 hz.
Granted, 200 feet is extreme..however it points out why Max's assertion of length invariance is accurate when the cable impedance is close to the load.
Cheers, John
I cannot answer for them.
I expect there is a range, from scam artists to those who are sincere. As to cost, I cannot answer as to their labor or markup. But it is certainly easy to diy any cable z desired.
My concern is understanding of the problem, and why I detail the t-line issue, the localization issue, the e/m theory...
Once goals are established, making the cables are easy. This being a diy site, I present what I can so that others can make what they wish.
If they wish to make a speaker cable which has a low characteristic impedance, they can understand what the ramifications will be (if any) on their system.
In the past, I've detailed how to make a cable of any desired characteristic impedance, from the physical design, the calculations, and the building.
A valhalla clone, a triaxial line cord (I do not recommend this as it is not UL listed nor NRTL approved), double braid coaxial speaker wires 6 ohm #14awg, and flat braid stripline speaker wire 8 ohm #12awg..
Nothing I've made ever exceeds a buck a meter, give or take..parts of course..I cannot afford my own labor.
Cheers, jn
Localization is a different beast. I was shocked at the low microsecond numbers as well..
jn
A triangle wave i.e. constant rate of change so skin depth is constant. If broken into Fourier components the distortion would reappear so I guess superposition does not apply (makes sense in a nonlinear system).
I only wanted to prove to myself that substituting a lumped L/C for the transmission line gave the same results from several angles. The transient response showed 2.5us on both and the frequency response/phase plots were directly on top of each other. A plot of group delay was flat and about the same consistent with a 2.5us delay with the 2 Ohm load.
So my conclusion is the speaker cable's transmission line nature can be ignored in your delay calculations. I still want to see the IAD studied in a free field with speakers and an ordinary room.
EDIT - I see now your different emphasis, does cable choice change the variation of delay not just does a continuous vs. lumped analysis give very different answers.
I only wanted to prove to myself that substituting a lumped L/C for the transmission line gave the same results from several angles. The transient response showed 2.5us on both and the frequency response/phase plots were directly on top of each other. A plot of group delay was flat and about the same consistent with a 2.5us delay with the 2 Ohm load.
So my conclusion is the speaker cable's transmission line nature can be ignored in your delay calculations. I still want to see the IAD studied in a free field with speakers and an ordinary room.
EDIT - I see now your different emphasis, does cable choice change the variation of delay not just does a continuous vs. lumped analysis give very different answers.
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The way we induce our brain in error with this stereo landscape build by two loudspeakers explain why we localize instruments in a sort of frog in our listening room.
Moving our head do not change the relative delay between the two ear and that is not 'normal'.
The way we use half of the available methods (level and phase) to build fake localization does not help too.
I had tried to add the two, in some mixs. Level + delay. Instruments where a lot easier to localize in the virtual space.
I wonder why, in numeric mixing desks, nobody had this nice idea to offer a panoramic button acting this way. Money ?
I would like to add that we use our eyes to confirm sound localization. It is an automatic process. Without images to confirm, it introduce some sort of fatigue. Our brain feel something is abnormal. That the reason why we all close our eyes, when we try to localize instruments, listening records.
By the way, if i was able to feel *very* slight differences in the textures of the sounds between cables, at the time i was exploring that domain, i was unable to feel any differences in the localization area. Some have an other experience ?
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For some strange reason I would be interested in experiments showing diode distortion at the PPM level in copper cable.
Clear vinyl insulated wire does indeed show corrosion with time in normal use. My current OPINION is that sulfur is the most interesting problem. In silver for example, the oxides conduct well, but the sulfites do not. More interestingly the sulfur attaching to the silver creates larger molecules which may actually prevent metal to metal contact under some conditions. I have not looked at this for copper.
The clear vinyl affected copper wire does show markedly increased resistance in some extreme cases. (I have seen and measured this.) The usual problem is that the bad stuff in the insulation that causes the change also affects a bit past the insulation so that I have seen crimp connections to such wire fail effectively open circuit.
That such a mechanical fastener shows long term fail in my OPINION indicates that the metal to metal contact is lost.
Now I suspect it is well known that changes in the resistance of the loudspeaker wiring will change the frequency response as the load impedance is not constant. What is not as well known is that loudspeaker impedance also changes with level, so true dynamic range will also be reduced. I have seen it demonstrated on musical program that a 1/2 db change at a particular frequency can be noted. I have not seen a demonstration of what a shift in dynamics will have. I can only suspect what a differential (in a stereo image) level shift would do.
Clear vinyl insulated wire does indeed show corrosion with time in normal use. My current OPINION is that sulfur is the most interesting problem. In silver for example, the oxides conduct well, but the sulfites do not. More interestingly the sulfur attaching to the silver creates larger molecules which may actually prevent metal to metal contact under some conditions. I have not looked at this for copper.
The clear vinyl affected copper wire does show markedly increased resistance in some extreme cases. (I have seen and measured this.) The usual problem is that the bad stuff in the insulation that causes the change also affects a bit past the insulation so that I have seen crimp connections to such wire fail effectively open circuit.
That such a mechanical fastener shows long term fail in my OPINION indicates that the metal to metal contact is lost.
Now I suspect it is well known that changes in the resistance of the loudspeaker wiring will change the frequency response as the load impedance is not constant. What is not as well known is that loudspeaker impedance also changes with level, so true dynamic range will also be reduced. I have seen it demonstrated on musical program that a 1/2 db change at a particular frequency can be noted. I have not seen a demonstration of what a shift in dynamics will have. I can only suspect what a differential (in a stereo image) level shift would do.
It is my OPINION that the soft vinyl has chemical components that outgas and cause the problem. It is worse than copper just left out in the open.
Ah, thank you. An interesting thought..
I have consistently stated that my use of the t-line model has been to more easily visualize the effect of using a low z load on a high z line.
I have also stated that when both models are done correctly, they must converge to the same answer.
I have never seen an emphasis on the line to load ratio causing a change in delay. T-lines very easily show this in an elegant way. Using multiple LC's in a model does not give a nice gut feeling. Nor does it easily show that under a specific condition (Zload = sqr(L/C)), all "filling" delays vanish leaving only the prop delay.
As you have shown in your modelling effort, both t-line and lumped can arrive at the same thing.. I like t-line because I can easily toss it into an excel sheet and make many graphs very cheaply....I like graphs...
So sue me, I used the "cheap" and easy model..
Cheers, jn
skin effect is a Linear EM phenomena in non ferromagnetic metallic conductors - no new frequency components are created with linear load and skinning/proximity current crowding in the cable
it is however a distributed/continuous phenomena like the transmission line properties of the cable - so the frequency domain representation can use "fractional poles" and have a ~ sqrt(f) impedance variation
skin effect can be modeled to any desired degree of accuracy with linear R, linear coupled mutual inductors - just build a mesh/lattice and refine the grid size/number of discrete elements - take the limit...
in the same sense delay of the transmission line doesn't have a finite, integer power of s laplace polynomial expression but can be well approximated by many discrete RCL sections
it is however a distributed/continuous phenomena like the transmission line properties of the cable - so the frequency domain representation can use "fractional poles" and have a ~ sqrt(f) impedance variation
skin effect can be modeled to any desired degree of accuracy with linear R, linear coupled mutual inductors - just build a mesh/lattice and refine the grid size/number of discrete elements - take the limit...
in the same sense delay of the transmission line doesn't have a finite, integer power of s laplace polynomial expression but can be well approximated by many discrete RCL sections
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Hum...
Long time heavy power increase temperature of the moving-coil. R increase with temp, that is for sure, so, efficiency (and Q factors) will decrease.
But i believe temperature inertia is far away from the audio range. Specially in trebles. Or, to be more precise, instant variations of impedance is out of scale. If you use multi ways enclosures, the differences of temperature can change slightly the response curve as each loudspeaker (bass, medium, treble) will goes at a different temperature, and his efficiency will change differently than the other's one.
But there too, i think (personal) that this change will be little, comparing with fetcher and Munson characteristics of our ears.
We can mention too that the changes in Q factors of the loud speakers will change the bass reflex tune. But less than air temp, i think.
So, if i was asked this question i would have answered that, because the only interesting dynamic is the instant dynamic, this effect is out of concern. Changes in Loudspeakers distortions will be hundred times more a matter.
[edit] If 1db was fixed at that scale because it is the littlest instant change in level an average ear can hear, our ears are not so precise with evaluating the absolute power. I think even 3db (two times the power) is difficult to determine on the long term.
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I would like to add that harmonic composition of sound changes our perception of power. Adding little pair harmonics to a signal, without changing the measured power, will give the feeling of an increased reproduced power.
Is that the reason why some people says that tube Amps give better dynamic ?
That for sure the reason why my wife was often asking-me to reduce the volume when i was playing Led Zep tunes ;-)
Is that the reason why some people says that tube Amps give better dynamic ?
That for sure the reason why my wife was often asking-me to reduce the volume when i was playing Led Zep tunes ;-)
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The plasticizers and clarifiers that need to be added to the vinyl compound to get it clear and keep it from embrittlement, plus the lack of non-reactive mineral filler.
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