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Sensitivity of opamps to air coupled EM fields, especially of the LM4562/LME497X0 family

ajawamnet

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For those who may be interested, -the prologue of Lorenz paper below translated from its Dutch language
https://en.wikipedia.org/wiki/Hendrik_Lorentz

https://ilorentz.org/history/proefschriften/sources/Lorentz_1875.pdf

"With a theoretical investigation of the movement symptoms der electricity came maxwell 1) the remarkable result,that there is a large agreement between sum some electrical movements and the aether vibrations that one to explain the light phenomena. He found,
that in a dielectric body there are vibrating movements of the elec can take place in the same way and with propagate the same speed as the light vibrations. The correspond The mood is so great that Maxwell gave rise to the under that in reality the light would consist of such electrical vibrations, a hypothesis, which he for some cases to the experience and therefore to a certain extent found.


Regardless of maxwell and others, lorenz is also 2) came to such results. Later, Helmholtz 3) joined the compilation of the movement equations of electricity the most general expression used for the inducing action of may incorporate power elements while undergoing maxwell and lorenz special assumptions about that operation were made. Helmholtz now found that also with that more alga for the consideration of the subject obtained by maxwell result essentially remains. He also commented to a circumstance that was not discussed by maxwell. He says namely 1) of the agreement found by them:This analogy is not very much in any other important relationship before hands which sir maxwell has not touched. You have the mecha niche state of the light ether some media so far see the fixed nel as ti Body equal set. This assumption results but for the border of two more transparent Media other boundary conditions, as a man,around the refraction and reflection of light to explain this limit, so here
theorists optics an unsolved contradiction files. The theory of electricians However, oscillations do not only result in the inside a similar insulating medium, but also on the border of two such media, the same laws of reproduction, the refraction and reflection of the waves, who we Light that find, provided that one can use either the magnetic or the dielectric polarity capability of both media the same and the latter is very large.

Of the designated alternative it depends on whether the electrical or magnetic oscillations of a polarized beam in the plane of polarization. "
It was this comment from Helmholtz that gave me cause to investigate to what extent the phenomena of reflection and refraction of light give rise to Maxwell's theory preferable to the previously adopted undulation theory.


In the first chapter I have the. difficulties discussed, which the latter yields in this regard. After then in the second chapter the movement equations of electricity I have the hypo in the last four chapters thesis by maxwell, or the electromagnetic theory of the light. In addition, the
reflection and refraction of light by non-conductive, isotropic substances, the optical properties of crystals, the theory of total reflection and finally the reflection of the light metals.

As the above-mentioned words from Helmholtz show,is a part of the results that I have obtained, already before
distracted by him. However, I do not know that he is more has written the quoted about this subject.


https://en.wikipedia.org/wiki/Faraday_effect

"Discovered by Michael Faraday in 1845, the Faraday effect was the first experimental evidence that light and electromagnetism are related. The theoretical basis of electromagnetic radiation (which includes visible light) was completed by James Clerk Maxwell in the 1860s and 1870s and Oliver Heaviside. This effect occurs in most optically transparent dielectric materials (including liquids) under the influence of magnetic fields. "

What's interesting is that during his experiments he used a piece of glass that he made during the time Davy made him go try and make glass - which ended in a horrible failure. Faraday didn't like applied science - also German glass making at the time was as much art/craft as it was science.

Davy didn't dig the fact that some people at the time - after Faraday's use of electromagnetism to make what was basically the first electric motor - said that the most important discovery Davy made was Michael Faraday... that and Davy's wife was a Bi$#$tch...

Later in Faraday's life - when people thought he was nutz with his talk of fields - Maxwell was one of the few that realized he was right. Faraday didn't have the math chops (he was pulled out of school by his mother at an early age) but Maxwell - coming from a fairly affluent family did have the maths and the rest is history... There was a great newer episode of Cosmos that sort of went into his life.
 
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SIY

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If photons can be generated, can the same photons emitting also then create a pathway allowing external light to enter at that same moment. ?

Yeah, they come bursting through the case and can blind the unwary user. They blow photon-shaped holes in the encapsulant allowing other photons to sneak in.

I'm not even going to bother trying to guess the relevance of all the other irrelevant stuff in your posts.
 

Wombat

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Don't audio photons behave like audio plankton?
 

SIY

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Don't audio photons behave like audio plankton?

This is an excellent point- like single-cell creatures, photons do tend to multiply by dividing. That causes temporal smear.
 

restorer-john

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"Opaque housings." Note that if you illuminate the innards of any actual piece of engineered audio gear, it has zero effect. I even did this to a forward biased LED in response to some online fretting about noise pickup (I used the LED to bias a phono stage).

Back when I was a kid, I used to scrape the black paint off early OC-xx glass tube germaniums to make ( pretty poor ones) phototransistors for my projects.
 

restorer-john

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This sort of exercise just creates misleading FUD, and seems a repeat of the amplifier load thread.

Just because you don't like the discussion, the methods or the conclusions, doesn't mean it is "misleading FUD".
 
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pma

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The "misleading FUD" argument reminds me PR department reasoning, as many of other posts of him.
 

March Audio

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Just because you don't like the discussion, the methods or the conclusions, doesn't mean it is "misleading FUD".

I have no problems with the discussion in general. Dont forget I have repeatedly talked about the importance of RF filters on the input to amps for example.

I take issue when someone does extreme things and then implies it is relevant to normal usage, ie putting large caps directly across the output of amps, or setting up tests that are nothing like used in any normal audio circuit.

Its misleading and unhelpful.

Op amp sensitivity to RF is nothing new, we know it can happen.

If you try hard enough you can break anything, and that appears to be Pavels modus operandi.
 
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March Audio

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The "misleading FUD" argument reminds me PR department reasoning, as many of other posts of him.

So, are your results with the ne5532 in any way representative of the results found when configured in a normal audio circuit and competent associated design?

Are you saying the thousands of audio NE5532 circuit designs over the past 40 odd years are plagued with the issues you demonstrated?

I would say no on both counts.
 
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pma

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Another set of measurements – test circuit with gain 40dB (see post #1 Fig.16), opamps OPA637, NE5534, OPA1611, OPA1641, ADA4898, OPA209, AD4627. Measured January 2011.

40dB_5534.png


40dB_4898.png


40dB_4627.png


40dB_1641.png


40dB_1611.png


40dB_637.png


40dB_209.png
 

restorer-john

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So, are your results with the ne5532 in any way representative of the results found when configured in a normal audio circuit and competent associated design?

Are you saying the thousands of audio NE5532 circuit designs over the past 40 odd years are plagued with the issues you demonstrated?

I would say no on both counts.

So you ask Pavel two questions and then proceed to answer them your way.

Is this a fair way to ask somebody something? Do you think that is a reasonable, adult discussion tactic?

I would say no on both counts.
 

March Audio

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Wombat

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So, are your results with the ne5532 in any way representative of the results found when configured in a normal audio circuit and competent associated design?

Are you saying the thousands of audio NE5532 circuit designs over the past 40 odd years are plagued with the issues you demonstrated?

I would say no on both counts.

Not all audio circuits are normal and competent in this day and age and the average punter can't tell what is what. Refer ASR test results.
 

March Audio

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So you ask Pavel two questions and then proceed to answer them your way.

Is this a fair way to ask somebody something? Do you think that is a reasonable, adult discussion tactic?

I would say no on both counts.

Its perfectly reasonable to provide my opinion to those questions. If Pavel disgrees he needs to show why.
 

March Audio

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Don't overestimate ASRs influence.
? Im not. This is something that good designers are aware of and if it were a problem it would show in their own testing. There is little we can do about those that dont test or dont care about the results.
 
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stereo coffee

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Yeah, they come bursting through the case and can blind the unwary user. They blow photon-shaped holes in the encapsulant allowing other photons to sneak in.

I'm not even going to bother trying to guess the relevance of all the other irrelevant stuff in your posts.
Exaggerations are sometimes helpful, so thanks for that. I doubt though, that light emissions from semiconductors are DC in nature.
 

restorer-john

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Not all audio circuits are normal and competent in this day and age and the average punter can't tell what is what.

And to be fair, there were a lot of abnormal and incompetent designs in the distant past as well.

The difference was, in my opinion, much of those errors were caused by the manic pace of development and extreme marketplace competition along with pressure on those wonderfully skilled engineers to beat their competitors to market.

These days, there is no excuse for flawed designs, as most, if not all the hard work was done by luminaries and legends before. Standing on the shoulders of giants with little self deprecation or acknowledgement is the order of the day, it would seem.
 

stereo coffee

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And to be fair, there were a lot of abnormal and incompetent designs in the distant past as well.

The difference was, in my opinion, much of those errors were caused by the manic pace of development and extreme marketplace competition along with pressure on those wonderfully skilled engineers to beat their competitors to market.

These days, there is no excuse for flawed designs, as most, if not all the hard work was done by luminaries and legends before. Standing on the shoulders of giants with little self deprecation or acknowledgement is the order of the day, it would seem.

Let's hope not so, to the ending of the last paragraph. Electronics history though is full of bully tactics. We can learn from Major Edwin Howard Armstrong and the suffering he went through, at the hands of David Sarnoff as one example http://www.njarc.org/books/man-of-high-fidelity.pdf
 
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