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commsysman
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Re: hmmm

Has it ever been demonstrated that this "integrated common centroid" issue is in fact an issue?

I think not.

I very much doubt that you can document any professional paper on this issue from the Audio Engineering Society or any other credible source.

I have heard nothing but audibly perfect results for the last 30 years of using balanced connections; I will just go with my experience until someone PROVES that there is some flaw.

I have yet to see it from you or anyone else.

P.S.-I taught electrical engineering for 30 years; if you can state it, I can assure you that I can understand it...if it indeed makes any sense.

KBK
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Re: hmmm

Ok. I'd like you to fire one bullet down two barrels. When at the impact point, I'd like the bullet to somehow reform into a single one and impact with singular utter perfection-in all ways.

Thank you.

commsysman
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Re: hmmm

I think your barrels just exploded; I hope you weren't hurt too seriously.

By the way...were those wine or whiskey barrels...?

j_j
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Re: hmmm


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Ok. I'd like you to fire one bullet down two barrels. When at the impact point, I'd like the bullet to somehow reform into a single one and impact with singular utter perfection-in all ways.

Thank you.

This has what to do with anything at all?

geoffkait
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Re: hmmm

Gosh, I can't remember the last time I saw so many strawman arguments in one place.

commsysman
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Re: hmmm

"Arguments"...???

Personally; I try to limit myself to stating my own opinion and experience, and perhaps some observations of accepted engineering principles. I refrain from any form of "argument".

It is impossible to "argue" with the fact that my observations and experiences exist (one could call me a liar, or deluded, but that is not an argument at all), and engineering principles have a way of changing only when they are disproved.

I stick to stating my opinion and try to provide a basis for it; those who wish to differ may certainly do so.

The observer may try to decide what is valid, if he wishes.

commsysman
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Re: hmmm

It is quite obviously a demonstration of the impossibility and absurdity of combining ballistics with pseudo-philosophy.

j_j
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Re: hmmm


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It is quite obviously a demonstration of the impossibility and absurdity of combining ballistics with pseudo-philosophy.

Well, I was considering an obtuse joke about Schroedinger's cat, but I was afraid somebody would take it seriously.

geoffkait
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Re: hmmm

It is impossible to "argue" with the fact that my observations and experiences exist (one could call me a liar, or deluded, but that is not an argument at all), and engineering principles have a way of changing only when they are disproved."

Another Stawman arument. You're on a roll.

KBK
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Re: hmmm


Quote:

Quote:
Ok. I'd like you to fire one bullet down two barrels. When at the impact point, I'd like the bullet to somehow reform into a single one and impact with singular utter perfection-in all ways.

Thank you.

This has what to do with anything at all?

This was a bit of non-linear non sequiturial thinking when issuing a comparative. It was posed as being similar to the difficulties of perfecting balanced audio signal transmission, transfer, and/or translation. When someone makes farting noises at me, sometimes I fart back.

Careful with those linear brain cells. They can take over much of the mind when given their blinkered druthers. Rein em' in!

The argument about balanced being inherently better is long over. Did you not get the memo?

jneutron
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Re: hmmm

30 years of teaching electrical engineering. That explains a lot.

I find that it's many times the very experienced engineering and physics professors who are the most difficult to teach..either due to callous disregard for anything outside their experience, or just plain bull headedness. It comes up a lot in my line of work..

Please ask questions on things you do not understand. I will be happy to walk you through it, or provide references for you.

For a start, I recommend you take a course in EMC. Unless you do this, you will not understand what I am speaking of.

The one by Tom Van Doren comes to mind, or Ott's book on the topic.

If you have had nothing but perfect results using balanced connections, then you obviously do not do this for a living. Just ask the pro sound guys how many times they have to troubleshoot balanced systems. There is theory, and then there is life..

Hence my statement about you googling the Pin 1 problem, and DI boxes (DI stands for dielectric isolation)

Cheers, John

ncdrawl
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Re: hmmm


Quote:
(DI stands for dielectric isolation)

Cheers, John

hell, I thought it stood for direct injection.

when I was learning recording engineering(well, im still learning, but when I was green)... i was always taught that balanced was a "pro standard" only because it was good for long runs. apparently there is some greater potential for noise rejection, though I cannot say ive experienced it personally.

jneutron
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Re: hmmm

It's actually great for all runs long and short, as it is great at resisting noise.

The concept is that two wires running in the same path in space, will pickup the exact same noise voltage when the noise is caused by a time varying magnetic field. (This is exactly what ground loops do, capture magnetic field and turn it into current.) A differential input takes the signals from each wire, and subtracts them. A noise which is exactly the same on both wires will cancel.

A coaxial cable does this "identical noise signal thing" by virtue of the exact same center of "mass" for the conducted current in the wire. (current centroid).

A twisted pair does this by virtue of close proximity to one another, and the fact that over one twist pitch, they swap positions such that each wire on average has it's center of current in the physical center between the two wires. Hence the term "common centroid". And why it requires integration over a full twist pitch to be so.

For a coax, this immunity breaks down if the center conductor is not in the center...when the inner and outer do not share a common center, the magnetic field can go between the centers and cause a voltage between them. It also breaks down when the cable goes near a high field gradient, such as the corner of an E-core transformer. This causes a higher induction on the shield closer to the source and lower away from it. High gradient means the field drops off at faster than 1/R rates such that the coax shield diameter looks large to it...low gradient fields do not induct a differential within a small coax.

For a twisted pair, we are counting on the fact that the field will go between consecutive loops in the twist, and the net average becomes zero. A source of magnetic hash which is far from the cable will impact alternating loops in the twist the same way, being cancelled.

If the pitch is 10 inches for example, the cable immunity is good for distances >>10 inches, and bad for distances under 10 inches. A magnetic hash source that is 2 inches from the cable, it will affect the closest loop the most, and that will not be cancelled by the other loops.

A twisted speaker cable or line cord, for example, can couple to a twisted differential pair if the pitches have an integral relation, and the wires are closer in proximity than the twist pitch of the "victim" cable. Cat5e stops this by specifying the exact pitch each pair must have, and all are different. Note that a braid shield cannot stop this coupling at audio frequencies.

A snake cable is another good example. If one used one of the pairs to run speakers back to the stage, and others for line or mike feeds, the agressor cable and the victim cable will have identical pitches, will be close together, and will absolutely communicate. A good friend of mine, his church was setup like this, and the tweeter crossover components were fried. The tweeters were not in good shape either....

Remember, in all cases, the shield is an electrostatic shield at audio frequencies, and is incapable of stopping any audio frequency from going through the shield to get to the wires.

Cheers, John

DI...Double Indemnity perhaps?

ps..pardon the length...some of this was for commsysman's benefit.

Scott Wheeler
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Re: hmmm

And I still have no idea what actual connectors meet the standards set forth in the article as optimal. Some how I had this idea that this would turn into a thread with some utility.

j_j
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Re: hmmm


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And I still have no idea what actual connectors meet the standards set forth in the article as optimal. Some how I had this idea that this would turn into a thread with some utility.

Sorry about that. I don't have the primary data. But well-plated gold would appear to be a winner here.

commsysman
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Re: hmmm

Your attempts to insult me would be offensive if they were not so completely ineffectual.

You can always identify an intellectually limited person by the fact that they have a deep-seated need to dismiss anyone with an extensive formal education as stupid, especially teachers.

After establishing a reputation over a 40-year period as an expert in my field, and earning the respect of my distinguished peers based on my work in my field, I am hardly going to feel challenged or insulted by someone like you who espouses absolute nonsense and displays a childish attitude. My average 19-year-old electrical engineering student is far more intelligent, knowledgeable, and mature.

The idea that you are capable of insulting me is ridiculous; I would have to respect you before you could even begin to insult me, and your statements so far contain absolutely nothing that is going to make anyone respect you; quite the contrary.

As for asking you questions...I only have one. Where is the documentation I asked you for earlier regarding the ridiculous "integrated common centroid" that you alleged to be a significant issue? You opened that topic, then dropped it like a hot rock when asked for some actual proof or documentation (one suspects that the whole thing is nonsense that you made up, and that none exists...). Let's deal with that alleged issue before you throw any new nonsense or insults into the pot.

If you can't even deal with that one questionable issue adequately, after attempting to make a major issue out of it, why should anyone even begin to consider anything else you have to say?

Scott Wheeler
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Re: hmmm


Quote:

Quote:
And I still have no idea what actual connectors meet the standards set forth in the article as optimal. Some how I had this idea that this would turn into a thread with some utility.

Sorry about that. I don't have the primary data. But well-plated gold would appear to be a winner here.

Thanks JJ, I guess I am just having a bit of trouble figuring out what connectors would be well plated and which ones would be considered not so well plated. The shiny standard doesn't seem to help as they all look shiny to me.

KBK
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Re: hmmm

The deal is that if you could get rid of about 90% of the metal in most audio connectors they would sound a lot better. The metal is the conductive path but it is also a major source of sonic issues.

Scott Wheeler
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Re: hmmm


Quote:
The deal is that if you could get rid of about 90% of the metal in most audio connectors they would sound a lot better. The metal is the conductive path but it is also a major source of sonic issues.

OK so can you name some connectors that get rid of 90% of the metal? All I am looking for here is some real world means of applying the information in the article.

michiganjfrog
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Re: hmmm


Quote:

Quote:
The deal is that if you could get rid of about 90% of the metal in most audio connectors they would sound a lot better. The metal is the conductive path but it is also a major source of sonic issues.

OK so can you name some connectors that get rid of 90% of the metal? All I am looking for here is some real world means of applying the information in the article.

http://www.soundfountain.com/amb/bullet.html

Scott Wheeler
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Re: hmmm


Quote:

Quote:

Quote:
The deal is that if you could get rid of about 90% of the metal in most audio connectors they would sound a lot better. The metal is the conductive path but it is also a major source of sonic issues.

OK so can you name some connectors that get rid of 90% of the metal? All I am looking for here is some real world means of applying the information in the article.

http://www.soundfountain.com/amb/bullet.html

A tip of the hat for the first practical recomendation. And they are reasonably priced to boot.

ncdrawl
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Re: hmmm


Quote:
Your attempts to insult me would be offensive if they were not so completely ineffectual.

the only hostility I sense is coming from you. JN appears to be a professional, knowledgeable gentleman.

MJF, thanks for the link. Much appreciated.

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Re: hmmm


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A tip of the hat for the first practical recomendation. And they are reasonably priced to boot.

An effective but not a connector-practical answer, well-known already, is to directly solder the cable to the equipment. No connectors at all. Not trying to change the discussion direction; just wanted to mention this.

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Re: hmmm


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An effective but not a connector-practical answer, well-known already, is to directly solder the cable to the equipment. No connectors at all. Not trying to change the discussion direction; just wanted to mention this.

It should also be mentioned that it's not for everybody. Yes, it can improve the sound; as a straighter path is generally the ideal path. But it's not a perfect solution either. e.g. I've soldered wire directly to speaker drivers, but whether amps or speakers etc., you need to set up some serious strain relief. Otherwise, you're at a great risk of breaking the solder tabs on the equipment. And if you do this, you'd better hope you don't change your mind on the cables later! If your friend tells you "You gotta check out my new cables, man!", just say "no". Because you might end up liking them.

j_j
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Re: hmmm


Quote:

Quote:
A tip of the hat for the first practical recomendation. And they are reasonably priced to boot.

An effective but not a connector-practical answer, well-known already, is to directly solder the cable to the equipment. No connectors at all. Not trying to change the discussion direction; just wanted to mention this.

Kinda tough for most equipment, but the results in the article make it clear soldered connections beat all.

KBK
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Re: hmmm

Oddly enough, solder is not actually an electrical connection, although the entire audio industry (and every other industry for that matter) has been treating it like it is - for over 40 years. Only metal to metal contact is a proper electrical connection. The solder is supposed to be just the mechanical anchor.

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Re: hmmm


Quote:
Oddly enough, solder is not actually an electrical connection, although the entire audio industry (and every other industry for that matter) has been treating it like it is - for over 40 years. Only metal to metal contact is a proper electrical connection. The solder is supposed to be just the mechanical anchor.

And the flux gets rid of oxides on the connection, and the solder keeps oxides from growing. It's not JUST mechanical.

Scott Wheeler
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Re: hmmm


Quote:

Quote:
A tip of the hat for the first practical recomendation. And they are reasonably priced to boot.

An effective but not a connector-practical answer, well-known already, is to directly solder the cable to the equipment. No connectors at all. Not trying to change the discussion direction; just wanted to mention this.

That might make for an interesting discussion on another thread. but seeing how this one started out as a thread about connectors and some of us simply are not going to solder our cables into our equipment......

geoffkait
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Re: Smart Metal

An effective but not a connector-practical answer, well-known already, is to directly solder the cable to the equipment. No connectors at all. Not trying to change the discussion direction; just wanted to mention this.
------------------------------------------------------------------------
"That might make for an interesting discussion on another thread. but seeing how this one started out as a thread about connectors and some of us simply are not going to solder our cables into our equipment......"

Even if one solders the connections, it begs the question of what is the best solder: lead/silver solder (what percentage), solid silver solder, etc. and which brands. And what of existing solder connections elsewhere in the system, on speaker cables, speaker crossovers, the electronics - what exactly is the optimum for best sound?

And for solderless connectors, to be thorough, one really must evaluate the Mapleshade, Walker and Xtreme AV contact enhancement products, since they improve the performance of any metal contact - beyond Cramolin, Pro Gold, etc. cleaners/conditioners.

It also begs the question of how Smart Metal from PWB fits into the scheme of things. Smart Metal will improve the performance of ANY existing solder connections in the system - speaker terminals, speaker cables, capacitors in electronics, speaker crossovers, etc.

It all depends on what one is trying to achieve, but to announce that the Fat Lady has sung is simply being short-sighted.

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Re: Smart Metal


Quote:
It also begs the question of how Smart Metal from PWB fits into the scheme of things. Smart Metal will improve the performance of ANY existing solder connections in the system - speaker terminals, speaker cables, capacitors in electronics, speaker crossovers, etc.

Any?

It's an electronic panacea!

absolutepitch
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Re: hmmm


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And the flux gets rid of oxides on the connection, and the solder keeps oxides from growing. It's not JUST mechanical.

Right. I'm sure we were all taught to solder by making a solid mechanical connection first, heat the connection to melt the solder while the flux cleaned the surfaces of oxide and make sure to 'burn off' all the flux, then let the connection cool undisturbed.

I have heard from some people that silver solder is better than the tin-lead combo as for electrical connections. Any thoughts?

KBK
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Re: hmmm

lead based solders still give the best connectivity, with regards to self clearing/cleaning and flow, IMO. It has to do with the specific fluxes that the differing types of mixtures end up using-besides the fact of how lead works in solders (which is better). For example , my least favorite solders are all the 'eutectic' tri-solders (tin-silver-copper), the lead free ones.

A friend whom I buy components from, his Bro is deeply involved with a known solder company. The 'eutectic' tri-solders are not really eutectic, he says.

j_j
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Re: hmmm


Quote:
lead based solders still give the best connectivity, with regards to self clearing/cleaning and flow, IMO. It has to do with the specific fluxes that the differing types of mixtures end up using-besides the fact of how lead works in solders (which is better). For example , my least favorite solders are all the 'eutectic' tri-solders (tin-silver-copper), the lead free ones.

A friend whom I buy components from, his Bro is deeply involved with a known solder company. The 'eutectic' tri-solders are not really eutectic, he says.

Lead, in particular, dissolves copper a bit when it's melted, and this also helps to ensure good connections. Some of the chemistry is quite interesting, and rather more complex than "melt lead/tin and let it flow around connections".

geoffkait
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Re: Smart Metal

It also begs the question of how Smart Metal from PWB fits into the scheme of things. Smart Metal will improve the performance of ANY existing solder connections in the system - speaker terminals, speaker cables, capacitors in electronics, speaker crossovers, etc.
------------------------------------------------------------------------
"Any?

It's an electronic panacea!"

I certainly didn't mean to imply it was for everyone.

commsysman
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Re: hmmm

IF you actually READ the gibberish, nonsense, and insulting comments in his last 4 posts, and that is your carefully considered opinion, then I guess he isn't the only one who is intellectually limited...rofl.

(Example: "...further compromising the low frequency centroid positioning..."...! And this is supposed to be a relevant statement about some supposed deficiency of balanced cables??...give me a break. Pure gobbeldy-gook!)

I strongly suspect that you jumped in with your two cents worth without going back and observing the entire conversation (and who invited you to butt in to the conversation anyway...are you suddenly the moderator of this forum?).

commsysman
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Re: hmmm

Excuse me, but one does not want to "burn off" the flux while soldering a connection.

I attended a 80-hour NASA Certification soldering school at Rockwell when I was a technician there (in Orange County, by the way...) and we were specifically instructed to NOT maintain heat too long and burn the flux off.

The reasons for the flux are two-fold:

1) to help dissolve and remove any slight contamination and impurities during the heating phase

2) to coat the solder as it flows and then cools, minimizing oxidation

Flux should never be "burned off" but dissolved and removed by washing with a suitable solvent after soldering is completed and the flux is partially cooled (most fluxes are most readily removed while they are still somewhat warm, however...not cold).

"Burning off" flux overheats everything, leaves an ash residue, and is likely to damage components and delaminate circuit boards. Heat should be removed immediately after the solder has flowed onto the surfaces to be joined.

Welshsox
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Re: hmmm

Hi

I have also attended the NASA soldering course and this is 100% correct, the flux is washed off with isoporopyl alcohol not burnt off

Alan

KBK
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Re: hmmm

How did we devolve down to burning flux off? It's moving down to the level of two Scots trying to give each other the hairy eye as they argue about whether the shots should be 1.1oz or 0.9oz, depending on who's doing the drinking and who's doing the paying.

We should stop there and try and reset the conversation.

Now, what was that? Something about quality of connectivity?

Surely the minutiae of the whole direction of conversation involves the plating, how those platings where enacted, the physical parameters (of the connectors proper), the abrupt changes in impedance and such brought about by differing connectivity issues, like solder and the connector itself to how the connector physically mates with the transmission line, how that affects the whole line itself insofar as the manifold field development and what all that means to the development and expression of the complex signal field in the line proper, which in the case of a single expression of the signal, involves the whole chain.

What do I mean by that? Well, the signal begins at the earliest point of translation, ie a transistor or tube proper. That is one anchor point of the developed signal 'body' proper. It then terminates as an expression of a given signal on a transmission line at the NEXT point of translation, which is going to be an active circuit.

Therefore, the end leg of the given transistor, the solder pad it is connected to, the copper trace, the solder lug of the switch, the pins and contacts of the switch, the next thru-hole by the switch, the next copper trace, the wire in the thru-hole, the RCA female jack, the RCA male plug, the wire proper, the final (cable) end male RCA jack the female RCA jack, the wire going to the circuit board, the copper trace, the switch or volume pot lugs, the resistive trace of the pot (in this example) the output end of the pot's lugs, the trace on the board, maybe a resistor and it's associated legs and traces and then finally a leg on a transistor, the other end..the finishing 'translation device'.

In that entire path, the signal sees ALL of those parts, solder junctions, etc, at the same time. And each of them individually causes a delay or distortion in the signal that is unique.

All individually adding their distortions to the same signal all the the same time, but individual time smears. I'm calling it a time smear as this is the ultimate result as when there is a molecular interactive of the 'signal body' (which is differential pressure enacted upon mobile charge, one could say-think local polarized [grouped] vectoral spin differentials acting on a already spinning top with various perturbations, and you'll have it for the most part) that gives rise to a 'electrical function'. You get, ultimately, what amounts to a change in time, level, and overall composition of the given signal- compared to what it should be at that given moment.

Like a choir with 40 people in it. Each with their own set of headphones all individually listening to the original voice, isolated in a a room of their own.. where each is off doing their own thing with the original voice, but all not listening to each other ---but attempting to add their voice to the original idea but each making a slight change.

When you add the voices all together (at the end of this electrical chain) you can imagine it sounds quite mushy and distorted.

It's a good analogy for the layman,and that is who it is intended for, not the techies here. If you have a problem with the analogy, then make up your own which can do some good when helping the guy with no electrical knowledge understand the point that 'simpler is better' (in all ways) when it comes to handling signals.

All I have described is a simple , lets say, CD output that has a switch, going to that of a Preamp input. That's it. along the way there are about 40-60 different perturbations of the given signal. An this is on an idealized, near perfect system. Never mind what happens when engineers who don't get this stuff start adding tons of crap components and switches to the electrical situation.

Edited for spelling and grammatical mistakes, as I was rudely interrupted by real work before I could proofread.

jneutron
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Re: hmmm

Attempts? No attempt was necessary, you read into it what you wish.

And hostility? Whoa. If you re-directed the effort you've put into hostility into learning instead, that would be a good thing.

As I stated earlier...you need to first learn some basics in electromagnetic compatibility. otherwise, you will continue to be frustrated by terms which you do not fully understand.

It is clear from your reaction to what I have posted, that electromagnetic field theory is not your forte..that is fine, this stuff isn't exactly clear to many.

As I posted earlier, Tom Van Doren gives a lecture series. Had you taken it, you would have seen and learned the concepts of centroids, and common centroids. (I assume you know what "integrated" and "integral" mean.)

In his course, "Grounding and shielding of electronic systems", Chapter 4, "field containment, bandwidth, balance, and resonance", page 36, slide 4.4, these concepts are presented.

Your "years" of experience are of no use to me. What is useful, would be a real dialogue on the technical content.

I note that you have NOT discussed anything technical, but have instead avoided any technical content whatsoever.(edit:avoided technical e/m theory...I note that later within this thread you post excellent content regarding soldering technology...nice..)

As I stated, ask questions, I will be happy to teach you what you do not understand. Either online here, or through PM's.

Cheers, John

jneutron
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Re: hmmm

Hi jj.

Actually, when the soldering occurs, two intermetallic alloys of copper and tin are formed. I do not recall copper lead intermetallics in any analysis I've seen. (don't mean it's not there, but I've not read bout it.)

Cheers, John

jneutron
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Re: hmmm

Oh, that explains a lot. Perhaps you should have asked questions instead of getting hostile. What I speak of is plain and simple EM field theory..

ok...""further compromise the low frequency centroid positioning.."". I'll detail a bit.

A coax works because the magnetic field of the inner conductor is cancelled exactly by the magnetic field of the outer concentric shield. A concentric shield has no internal magnetic field. As a result, the only magnetic field in a cylindrically symmetric coax is between the inner and outer conductors. (edit..note: The field has the 1/R distribution as is expected of the inner conductor current, but this field drops to zero at the cylindrical shield because the shield magnetic field is equal to and opposite that of the inner core wire.)

This system works as long as the outer shield current is uniformly distributed.(edit: and as long as the net current at the section is zero, this is not the case for unbalanced grounded systems) In other words, the inner current centroid and the outer current centroid are in the exact same location. This is the term "common centroid".

If the inner conductor of the coax is offset, the current centroids are not lined up. The net effect is exactly the same as two unshielded wires which are spaced a distance apart which is equivalent to the centroid offset. This makes the coax susceptible to external magnetic fields.

At high frequencies, the current in the offset shield will re-distribute such that the centroids line up. A deformed coax will have an external magnetic field at low frequencies, but as the frequency goes up, the external magnetic field will reduce.

A twisted pair within a braid, by it's geometry, has both inner conductors NOT in the center of the shield braid. So each wire can pick up external magnetic fields. This effect goes down as the frequency goes up, because the shield centroid will still re-distribute as long as the braid interstrand conductance is good.

If you still do not understand, just ask..

ps..this is just basic stuff in my line of work, and electromagnetic compatibility has only recently started to come of age.

Tom was excellent btw, I'd recommend him to anybody. In the two day course, he had only two errors, and neither really were show stoppers.

Cheers, John

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Re: hmmm

I also agree, flux burnoff is not good.

When did you attend this school? Did they cover any non eutectic alloys? I assume flight hardware remains exempt..at least I hope so.

edit...

I have a huge amount of experience (we purchase several tons of the stuff, in bar form for pots, solid wire, and we had kester make us cored wire with R type flux..) with the tin/silver eutectic, and the visual criteria drove the technicians I taught soldering to... nuts...they always expected shiny, which tin/silver isn't gonna do.

I also had the added constraint that all soldering for the cryogenic environment had to be R type flux only. Only the room temp stuff was allowed to be lead/tin.

Cheers, John

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centroids..

Almost forgot...

1947, Terman published the equation for parallel wires. It is comprised of three components.
1. External inductance. This is the total magnetic storage. It is based on the centroid spacing of the two wires, and specifically the centers of two cylindrical wires.
2. Internal inductance. This is the 15 nH per foot value for a solid cylindrical wire, modified by the term "delta". Delta is .25 within his equation at DC, and requires a lookup "nomograph" for values at any frequency other than zero.
3. Length of loop compensation. This was added to accomodate wire loops where the field enhancement at the ends becomes significant..this is ignored for simple inductance per foot calculations.

Of note is the fact that there is no accounting for the effect the opposing conductors have on the current density profile in each conductor. In the high frequency magnetics domain, this is referred to as "proximity effect". Same in the EMC domain. Dr. Charles Sullivan at Dartmouth provides many very good papers online which detail this effect within both wires and high frequency magnetics. (sorry, do not have a link ready...but googling his name should bear fruit)

This is a result of eddy currents..consistent with Lenz's law. The eddies cause the current to re-distribute within the conductor. This forces the current centroid to move to one side of the wire.(edit: note that this is current centroid repositioning) Net result is less conductor carrying the current..higher dissipation results.

Within the EMC field, this crowding of the current closer to the other wire is explained as the current attempting to take the path of least reactance. The centroids moving closer to each other is causing a net drop of the system inductance...this can be seen via a simple inductance measurement..I use a nice HP puppy that goes from 20 hz to over a meg. In addition, it shows the effective resistance of the conductor as a result of the current crowding caused by proximity.

Litz is designed to prevent this. The interstrand insulation prevents the centroid from shifting more than one strand radius.

Leseuf has a great java app for calculation of inductance. I cannot tell if it is accurate at hf, as his depiction of current redistribution at frequency is not correct. Regardless of the conductor to conductor spacing and frequency, he depicts the current distribution (and consequently the current centroids) as remaining symmetrical about each wire's axis. So I cannot tell if the final inductance number is correct. Having the app draw the correct current density and centroid location may very well be outside the capabilities of java..

I fight this constantly in magnets, as superconductors have rather good conductivity..

Cheers, John

Edit:

Graeme, Jerald G, 1996, ""Photodiode amplifiers: op amp solutions""

Chapter 9, page 218
Quote:
The coaxial cable optimizes this canceling effect by producing a common centroid or axis for the two current flows.

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Re: hmmm


Quote:
Your attempts to insult me would be offensive if they were not so completely ineffectual.


There have been no attempts...therefore, ineffectual is a non sequitor...an attempt at diversion away from the topic.

Quote:
You can always identify an intellectually limited person by the fact that they have a deep-seated need to dismiss anyone with an extensive formal education as stupid, especially teachers.


Other than your post, where has the word "stupid" been used?

Actually, I would identify that kind of person by their use of diversionary tactics such as those you are enlisting. Since I have not accused you of sub-par intellect, it would be best if you stopped your sillyness and confine discussion to the topic..

Quote:
After establishing a reputation over a 40-year period as an expert in my field.....


I have never heard of you. What field are you expert in?
I think we can eliminate EMC.

Quote:
Where is the documentation I asked you for earlier regarding the ridiculous "integrated common centroid" that you alleged to be a significant issue? You opened that topic, then dropped it like a hot rock when asked for some actual proof or documentation


hmmm..Where did I drop it? Should you actually ask a question, I will do my best to answer it..
I guess pointing you to Henry Ott and Tom Van Doren is too much work, as is googling phrases such as common centroid.

Making these things up as you go along certainly does not help make your case...nor does ignoring discussion, nor does the vitriol you provide.

I have asked you kindly leave your anger elsewhere, it is misplaced here.

Cheers, John

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Re: hmmm


Quote:

Quote:
(DI stands for dielectric isolation)

Cheers, John

hell, I thought it stood for direct injection.

Funny funny funny.

I was looking up pin 1/phantom power/ di boxes, and what do I find???

Direct Injection....

I stand corrected...

Course, I don't know why anybody would call dielectic isolation that....

Cheers, John

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Re: Smart Metal


Quote:
Even if one solders the connections, it begs the question of what is the best solder: lead/silver solder (what percentage), solid silver solder, etc. and which brands.


The majority of the solder connections are decided based on mechanical considerations.

Tin/lead is the best when the joint is not strained.
Tin/silver is mechanically very strong, even down to 1.8 kelvin.

Pure tin....is a problem looking for a victim. Pest and whiskers...thank goodness ROHS forces us into throwaway electronics.

Copper added? sheesh, the solubility of copper in solder is temp based..add a coupla percent, who cares...

The flux is THE most important aspect. Yes, sometimes the really old solcer wire has a large lead surface, but that is an exception...

For all room temperature applications, I force everybody to use tin/lead.

For all cryogenic applications, I force them to use tin/silver. 96/4.

Room, RMA flux. Cryo...R flux...it's a bitch, but too bad. Hydrochloric acid destroys 6 mil thick stainless vacuum bellows..

There are NO non linear effects of the metals. Just joint integrity. Make it good, that is all that counts..

Cheers, John..

ps..where is that angry guy?

pps..how come I can't post pictures here???


Quote:
It all depends on what one is trying to achieve, but to announce that the Fat Lady has sung is simply being short-sighted.


The most important consideration is...what is the joint resistance, and what is the impact of that resistance..

Cheers, John

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Re: Smart Metal


Quote:

There are NO non linear effects of the metals. Just joint integrity. Make it good, that is all that counts..

Cheers, John..

Give me about, oh I forget... I'll have to check how much time before the paperwork goes public (viewable). Then we'll discuss this again. I do promise some 'freaky shit' that is verifiable and repeatable.

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Re: Smart Metal


Quote:

Quote:

There are NO non linear effects of the metals. Just joint integrity. Make it good, that is all that counts..

Cheers, John..

Give me about, oh I forget... I'll have to check how much time before the paperwork goes public (viewable). Then we'll discuss this again. I do promise some 'freaky shit' that is verifiable and repeatable.


Verifiable and repeatable is a good thing. However, the most important aspect will be the design of the experiment. Many attempts at measurement of some low level effect produce verifiable and repeatable results, yet the methodology was flawed. The important things which should have come out of the test...were not figured out by the experimenter.

Cheers, John

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Re: centroids..

Well, it sounds like you probably barely passed the 3rd semester of basic physics; congratulations on some rather confused knowledge of some basic EM theory. If you ever want to sign up for one of my graduate courses, we MIGHT be able to improve your knowledge in some of the areas you seem to be so theoretically weak in. The essential difficulty is that while you seem to have some understanding of the basic principles, when you attempt to apply them in a meaningful way to a specific case, your arguments become confused and ramble hopelessly. Throwing around a bunch of ill-conceived and highly questionable allegations couched in technical terms is not strengthened by citing a few non-relevant technical references; this does not impress anyone except the ignorant, so it might be wise to give up the attempt.

P.S.-(since you asked) My field is communications systems; Motorola and other companies frequently employ me as a consultant in systems design and propagation studies, especially in relation to antenna design for cell sites and large-scale public-safety radio systems in urban areas. Another specialty is intermodulation issues as they affect encrypted audio transmissions for public safety communications (police, fire etc.). As a professor and antenna design engineer, the idea that YOU would try to instruct me in electromagnetic theory (upon which I have lectured for many hundreds of hours) is an incredible joke (you sound a bit like a 9-year-old trying to lecture on sexual techniques...it really IS that ridiculous...). You have repeatedly demonstrated that your knowledge of the subject is very limited, so please don't embarrass yourself more than you already have.

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Re: hmmm

Re your question on the soldering course:

I took the course when employed by the Autonetics division of North American Aviation/Rockwell Corp. in the 1960s, in Los Angeles and then Orange counties. For a couple of years I was employed in the department where the Minuteman II ICBM D37 flight computers were functionally tested, and later in a department where Apollo flight electronics were assembled and tested for NASA. (interestingly, I went to an Air Force museum near Great Falls, Montana a few years ago, and they had one of those Minuteman II computers on display; they were still in use until around 1990, when they were replaced by a new generation flight computer using much more modern integrated circuit technology...the integrated circuits in the Minuteman II were the first ever produced on a production basis, and they were primitive by today's standards)

Tin/Indium solder was used for flow-soldering connectors to circuit boards (due to its low melting point; there were severe problems trying to prevent the delamination of multi-layer boards...the master interconnect board of the computer had 28 layers with 23 80-pin connectors soldered to it, and this was new technology at the time...). Conventional tin/lead solder was used to attach components to boards.

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