Wavebourn said:
I thought I was talking about longitudinal or compression waves traveling through air and the effects caused as they meet obstacles impedances on the surfaces (the outsides) of speakers and waveguides.
Among those effects is linear distortion of part of musical signal as it arrives at listening position.
You seem to thinking about something else not implied in my original post.
scott wurcer said:
I didn't have a transistor radio on hand for comparison so I can't really say.
That's just what the sound quality reminded me of. It clearly wasn't a transistor radio. The commercial preamp's circuit is a discrete op amp based topology with a total harmonic distortion of 0.002% at 2 volts output. So, this is a very different topology than my cascode, single ended preamp with no feedback THD < 0.01%. This same audio company is still building highly rated preamps way beyond what I can afford.When I was designing my preamp I did lots of A-B comparisons with this comercial preamp and I couldn't say one was really better than the other. They were just different, and there things I liked about both. Though, I thought my preamp edged it out overall. The way I see it, it was a familiar sound we handn't heard in several months, and conditioned reflexes need practice.
I've gone on hikes in the mountains with only nature sounds for half the day. When I'd come back to civilization I'd think "Ick! ... city sounds." But, I hear city sounds all the time and don't think anything of it usually. Don't even notice it when I'm not listening for it.
SY said:
1) Thanks SY.
2) OK, now I know why my science teacher committed suicide. 😀
3) OK, then I was supposed to say when current are flowing through the cable.
André
There's a difference between a current and a field. Now, there does need to be a potential difference for the current to flow, but that's at the ends of the conductor.
Metals exist as a crystalline array of nuclei and inner core electrons, with the higher level electrons delocalized in a generalized "cloud" that extends throughout the crystal. Reality is somewhat more complicated, but this basic model is 99% accurate.
Metals exist as a crystalline array of nuclei and inner core electrons, with the higher level electrons delocalized in a generalized "cloud" that extends throughout the crystal. Reality is somewhat more complicated, but this basic model is 99% accurate.
That holds only true for the electrostatic case.
Assumed a conductor is placed into an stationary (not time variable) e-field, then only for a _very_ short moment an inner e-field exists until the electrons are moved; afterwards only the outer field still exists (if not altered) but the conductor is free from inner e-field.
In the non stationary case there is constant directional movement of electrons and an inner e-field must exist.
Re: Re: Passives
Okay, I see what you're getting at. If the preamp was better than mine would I react the same way. Maybe not, I can't really say. I should mention that my preamp is a modification of one of Pass's circuit topologies. Thanks, Pappa Pass! 🙂 I certainly mean no insult to Pass or JC.
My point is that we can react to the same sound very differently, depending on the conditions.
Better often depends on your point of reference. I know when metal dome tweeters became all the rage, my dad and I stopped in a high end audio salon to hear the new Thiel CS1.2 or CS1.5? I can't remember. But, all the systems sounded brighter than s.... and they probably had them set up to sound like that also. And, when we asked about auditioning a highly rated Modulous preamp, they said it was too soft sounding and we wouldn't like it, but we auditioned it anyway. All these systems sounded great to them.
An accurate point of reference is really important I think. I mean, if accuracy is the goal.
scott wurcer said:
Okay, I see what you're getting at. If the preamp was better than mine would I react the same way. Maybe not, I can't really say. I should mention that my preamp is a modification of one of Pass's circuit topologies. Thanks, Pappa Pass! 🙂 I certainly mean no insult to Pass or JC.
My point is that we can react to the same sound very differently, depending on the conditions.
Better often depends on your point of reference. I know when metal dome tweeters became all the rage, my dad and I stopped in a high end audio salon to hear the new Thiel CS1.2 or CS1.5? I can't remember. But, all the systems sounded brighter than s.... and they probably had them set up to sound like that also. And, when we asked about auditioning a highly rated Modulous preamp, they said it was too soft sounding and we wouldn't like it, but we auditioned it anyway. All these systems sounded great to them.
An accurate point of reference is really important I think. I mean, if accuracy is the goal.
SY said:
Let's be specific here. The current density J in Amps per square meter is sigma * E, where sigma is the conductivity of the material. I'm assuming a linear, homogeneous, isotropic material. The current I is the integral of the normal component of J over the cross-sectional surface being considered (I = integral(J dot n dS)). So if you are to insist that the E field be identically zero everywhere inside a conductor, this is equivalent to saying there is no current flowing through the internal cross-section of the conductor. But that's equivalent to the perfect conductor case, in which the current flows in an infinitesimally thin sheet on the surface of the conductor. Or it could simply mean there's no potential difference between the two ends.
This brings up another interesting point. When considering wave propagation in coax, TEM mode is usually assumed. In that mode, if you pick a point along the center conductor and cut a plane perpendicular to the center conductor, the E and H fields will lie entirely in that plane. That is, there is no axial component of E or H. Yet if you assume there is current flowing through the center conductor that's not confined to a vanishingly thin sheet on its surface, that implies a non-zero E field inside the conductor, which must indeed have a non-zero axial component. Thus a true TEM mode in coax can only exist with lossless conductors. In the real world of lossy conductors with coax, there exist non-zero axial components of E internal to the conductor (assuming there's non-zero energy being conveyed to the load).
andy_c said:
J=sigma*E where J and E are vectors and sigma is generally a tensor of second order (covering the non isotropic, etc... cases), aka Ohm's law. 🙂
FrankWW said:
Yes, we were speaking about non-linearities when you chimed in with resonances and interferences-diffractions claiming that on higher SPLs they are more audible. Since audio sensitivity is logarithmic, on higher SPLs so called linear distortions should be less audible, but non-linearities caused by compression of an air and deformations of surfaces that transfer and reflect the sound cause additional colorations. Why do you think planar speakers (long thin membranes on heavy stiff frames) and phased arrays (many point sources with light cones, mounted on heavy stiff non-resonant panel) sound more natural than single powerful point sources with much bigger displacement? However, some line arrays have too big distances between drivers, so "linear" distortions are quite audible, but they are more linear than point sources.
Edmond Stuart said:
Reinventing the wheel and again and again and again?
No, I mean deep understanding. Do you remember a bicycle off-topic? Which model of feedback worked better? Who can construct and ride better bicycle, who understands physics behind it's wheel, or who learned well how to name certain parts of a Chinese-made bicycle passing multi-choice tests?
scott wurcer said:
Scott, the question was about why the higher is SPL the more audible are results of resonances, diffractions, interferences.
syn08 said:
Yup 🙂. I put vectors in bold in the earlier post.
I used to work on code that interfaced to EM simulators. The client code I worked on stored material properties and had the ability for epsilon, sigma and mu to be tensors. None of the simulators we interfaced with at the time had the capability of dealing with the anisotropic case though.
TRUST YOUR EARS, Johnloudb. NO RATIONALIZATIONS should take YOUR experience away from you. Shame on you, Scott! Badmouthing Walt's reality like that. 
It is good (I think) to attempt to talk about electrical flow in wires, BUT reality is even more complex than the engineering approximations that everybody learns in class.
john curl said:TRUST YOUR EARS, Johnloudb. NO RATIONALIZATIONS should take YOUR experience away from you. Shame on you, Scott! Badmouthing Walt's reality like that.
Walt pretty rarely espoused a belief in any of the excesses of the audiophile world. I don't think you would catch him buying any exotic inter-connects or speaker cables. DIY all the way! I still am using some of the wire he sent me. I also never had him recommend a single tweek device, like you know what.
Thanks for the replies to my post a while back!
As i said before continue the excellent banter!
As i said before continue the excellent banter!
john curl said:
Today's EM simulators are capable of accurately predicting electrical performance of physical structures up to millimeter-wave frequencies. I'm sure you will vigorously object to this statement, but the behavior of such structures in the audio frequency range is trivial by comparison.
The reason for all the audiophile cable products is that there is very high markup, lots of money to be made, and lots of people who have been fooled or are fooling themselves to sell them to. This is not to say the vendors themselves are necessarily dishonest. They may be fooling themselves as well. Many of these vendors are fond of claiming stuff along the lines of "we know very little about..." when in fact the problems have been beaten to death for ages. It's hard to know whether such statements are simply projection, or are intended to deliberately mislead.
IMO connectors are a different story though. It's essential to have very good ones. Yet despite all the voodoo, the high end audio industry has standardized on junk like RCA and banana connectors. What a joke.
Re: Iron, Fe, magnetic metal
opportunity
improved tubes
kamskoma said:Horror!
I found that the pins who sits at the bottom on tubes are M A G N E T I C, they are made of iron, can it be possible that the small tiny signals from a magnetic pick up have to stand this.
It is really Ok! a small virgin flute signal in IRON, many tubes and a lot of iron pins in a amplifier.
I have read a lot in this thread and understand that iron is totaly forbidden in the art of making audio electronics.
Or can it be so that iron is good for audio
😱
opportunity
improved tubes
Most techs/engrs. like to 'talk shop'.
they will gladly share, and demonstrate.
listen to them.
buy them some of their favorite drink.
buy them dinner.
be friendly.
visit off/on.
don't be rude. listen. learn. even if your schooling says they're wrong.
the phenomena is often real, even if the explanation of it is rubbish.
we don't always understand the 'why'
they will gladly share, and demonstrate.
listen to them.
buy them some of their favorite drink.
buy them dinner.
be friendly.
visit off/on.
don't be rude. listen. learn. even if your schooling says they're wrong.
the phenomena is often real, even if the explanation of it is rubbish.
we don't always understand the 'why'
Or it could mean that I'm trying to give a general picture to a guy who's curious but has zero background in physics or material science. 😉
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