John Curl's Blowtorch preamplifier part II

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In a conversation with O2 (cellular network) the other week about an RF cell issue, they in the end said, we don't have anyone who understands RF here anymore. We just drop a box (cell) into place and turn it on. We only have people who know how to use the GUI to configure them, and IT guys...
Oh, and we've dealt with their so called IT guys, that's another long story.

Why I am in a way glad to be out that game. Now given how p**** poor cell optimisation was when done mandraulically leaving the machines to get on with it can't be worse. Sadly radio quality means for little these days.
 
I would argue audio band IS DC. I wouldn't go as far as some of the microwave people I worked with who would scoff that anything under 1GHz was DC, but certainly the higher in frequency you go the weirder things get.

If I read you right you are saying that oxidation of the centre bundle will create a type of very poor litz wire? I must admit I had been thinking of a solid core when thinking of an easy experiment to show if surface oxidation can have a measurable effect. But interesting. I can't at the moment think of a way to corrode the inner without modifying the geometry or dialectric in a way that would skew the results.

Aside: I do have a fondness for semi-rigid on SMA connectors. It just takes impractical to new levels in a hifi, but handy internal hookup between boxes.

Seen some rf results (bare copper in air) will try and find the doc, but basically no difference as the oxide is effectively an insulator and works just like the insulating air round the cable, it is not used for conduction...
 
No just a reminder of a particular paper that is mentioned in more recent formal discussion.
That said, I have not thoroughly read the referred paper yet.

So, what is the takeaway from this particular paper, and what is the other stuff mentioned in IEEE Spectrum 7.16.

Dan.

It has appeared several time, mostly as proof of bybee devises, I can't be bothered to dig round the other threads (Bybee related it) appeared in.
As DF96 has commented it has zero to do with Audio and is just fodder for the Bybee crowd to wave at us sceptics...
 
What causes Inductance... flux density or no flux density?

Interesting question.

Inductance is the relationship between the current within the system, and the energy stored by the system.

E = 1/2 L I^2.

L = 2E/I^2

Flux lines are our way of expressing where the magnetic energy is. No flux, no energy.

At Lawrence Livermore National Laboratory, they are an applied science lab. I was told when I worked there they never hired theorists. If they have something not go as planned, they call a university for a therorists to give them ideas. LLNL has to make things that actually work. All people hired are world experts in the field they were hired/needed. They had practical experience. No PHD without experience were ever hired. Experience matters.
I am confident that there are people at LLNL who understand maxwells equations, and in this case, ampere's law as integrated within a uniform current of a round conductor carrying DC. As DF96 stated, there is an equation all physicists and EE's use to characterize the flux caused by current. I recommend you go back and speak to anybody there, revisit your understandings, as what you have written shows a failure to grasp the rudimentary understanding of ampere's law or the integration within.. The link I provided even shows the integrals and how they derive down to the flux level within the wire.

Now tell me again how skin effect is actually caused to happen? Or why the HF are at the surface?
THx-RNMarsh

As I said, the wiki recently discussed does have a good set of graphs and depictions of what actually happens. Please refer to it for a good understanding. (the is one of the few times I've actually referred someone to wiki, it seems to be evolving well.)

I would argue audio band IS DC. (I would agree) I wouldn't go as far as some of the microwave people I worked with who would scoff that anything under 1GHz was DC, but certainly the higher in frequency you go the weirder things get.

he may be correct and may not be in his model of how things work. Sorry JN.

THx-RNMarsh
Actually, I am correct. It is not a difficult concept, and actually just requires understanding of the fundamentals. You don't even have to do the calculus to follow the theory. And no apology necessary, we simply have a disagreement.

Jackson is not an easy text. Let me know if you would like referrals to other texts which are easier to read, I have a few on the shelf.

John
 
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How about a laugh - original on diyaudio!

"There's another benefit for using a fully differential amp. That is that both of the speaker wire connections are active voltage (as opposed to single-ended where the negative/black terminal is just ground). This means that you have two sides controlling the movement of the speaker itself. [] Using a differential amplifier will have more force on the magnet of the speaker because it's now a push/pull situation. A single-ended amp will be more "loose" in its ability to control the movement of the speaker."

Cracked me up!

Jan
 
RNM

Amplifier power ain't what it seems. I am finishing up an install. Powering each three way loudspeaker is a four channel 5,000 watt audio power amplifier. Two channels for the two woofers, one for the mids and one for the tweety. Measuring the RMS voltage we get a maximum continuous voltage of 40 volts. It does peak a bit higher until the power supply droops.

So those small little semi-custom doodads you showed earlier should be more than up to the task.

BTY the maximum output will be 6 dB or so less than what folks here calculated.

My current project is demonstrating that my approach to long length loudspeaker cables and taming switch amplifiers is a very nice improvement.
 
How about a laugh - original on diyaudio!

"There's another benefit for using a fully differential amp. That is that both of the speaker wire connections are active voltage (as opposed to single-ended where the negative/black terminal is just ground). This means that you have two sides controlling the movement of the speaker itself. [] Using a differential amplifier will have more force on the magnet of the speaker because it's now a push/pull situation. A single-ended amp will be more "loose" in its ability to control the movement of the speaker."

Cracked me up!

Jan

Also, in his defense, he is basically conceptualizing a bridged amplifier, which will indeed deliver significantly more power to the load by virtue of double voltage. Laymen may pick up this without consideration of the double voltage/double current aspect.

But yes, his confusion is quite evident.

John
 
No just a reminder of a particular paper that is mentioned in more recent formal discussion.
That said, I have not thoroughly read the referred paper yet.

So, what is the takeaway from this particular paper, and what is the other stuff mentioned in IEEE Spectrum 7.16.

Dan.
They have assumed that because the conductivity is two state as in on/off, that it is quantized.

Had I refereed that paper, I would have sent it back asking the simple question: How have you demonstrated that the on/off effect is not a result of a negative meniscus during the immersion? The results are consistent with an insulated wire being immersed. Since the assumption is ballistic transport within the tube, it is only logical that they do not broach the sides of the tube therefore the ballistic phase is within a constant gradient.

Also, it has nothing to do with audio. (gee, didn't DF96 say that??) ;)

John
 
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Interesting question.

Inductance is the relationship between the current within the system, and the energy stored by the system.

E = 1/2 L I^2.

L = 2E/I^2

Flux lines are our way of expressing where the magnetic energy is. No flux, no energy.

So? If we use the flux lines in a wire, we see the density varies and is least dense at the outside of the conductor.

I am confident that there are people at LLNL who understand maxwells equations, and in this case, ampere's law as integrated within a uniform current of a round conductor carrying DC. As DF96 stated, there is an equation all physicists and EE's use to characterize the flux caused by current. I recommend you go back and speak to anybody there, revisit your understandings, as what you have written shows a failure to grasp the rudimentary understanding of ampere's law or the integration within.. The link I provided even shows the integrals and how they derive down to the flux level within the wire.

Physicist, yes. There were not maybe 6 EE who used calculus on a regular basis.

Actually, I am correct.

John.


I am sure you are for the assumptions. I have read the conductance of copper oxide varies quite a lot.... depending on the purity of the copper or the impurities in the copper/oxide, for one. It can, after-all, can be a semi-conductor rather than an great insulator. We come back to ... what is the typical/normal condition in the home audio system.

But, I am more interested in how inductance is created using flux density in a wire to establish a theory for skin-effect.



THx-RNMarsh



As a comment on High-End audiophile RCA/XLR connectors -- there seems to be some who think gold plating, tight fitting and high purity copper is just marketing and eye candy, only. No. there are good reasons for these constructs.
 
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They're going to be a lot of fun.....I borrowed a pair of JBL L220's and HK Citation amp for a party once...went down very well.
Your M2's could also double as PA speakers for a duo/band etc at your next party. ;)

Dan.

The literature says they are also developed for cinema and broadcast production. I don't expect dynamic range compression at home listening levels... even parties. Now I need more HD recordings and mastering. Wish me luck on that. :)


THx-RNMarsh
 
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That's explained in just about any freshman E&M text, or Vol 2 of the Feynman Lectures.

and I already said what happens, also, in typical home wiring.

text book theory would say the flux is evenly distributed across the whole cross-section. In reality that condition does not always apply.

The diameter vs freq is an important element in whether this is true or not. Small enough diam and it is true. Larger and you run into the effect.

That practical side of things.

But, I agree it isnt a big deal, IMO, for home audio systems because as the wire diameter becomes large enough at HF for skin effect, the R is so small as to be negligible compared to the load.




THx-RNMarsh
 
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It is easy to spot the difference, precious metal connectors with features to assure a good mechanical contact exist and are readily available at a small premium.

Then there are things like the Eichmann Bullet sold with flowing pseudo-scientific nonsense.

Eichmann Bulletplugs vs WBT Nextgen phono plugs - [English]

and of course...
Mr Wurcer, I suggest you to buy pair of WBT Nextgen 0114/0210 pair of RCA connectors and use them in phono preamp input. I was skeptical, but they are close to no-connectors and give more details and lower noise than lower grade but decent gold plated connectors.. My IC is 1.5 Euro/m good quality twin-ax microphone cable. If they are good enough for recording studios...
Connectors are more important than cables.I know that it is against theory, but they are worth every cent.
 
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