If you re making reference to Hawksford s paper , i did understand it otherwise.
According to the author :
Make me think of output/input impedance adaptation for maximal energy
transfer , as is usually done in RF circuits with matching networks,
although in this case it s like he introduced some kind of quantic
limit to transistors amplification precision.
According to the author :
Make me think of output/input impedance adaptation for maximal energy
transfer , as is usually done in RF circuits with matching networks,
although in this case it s like he introduced some kind of quantic
limit to transistors amplification precision.
You are welcome..and thanks. The best part was it's simplicity. Having the v tap wire go in the center of the field to zero the loop area was the simplest of the possible solutions. I had considered putting a DCCT in, but we only had a 10 kiloamp one available and it didn't fit inside the rack, and it also didn't have the bandwidth I needed. My task was to measure the forward voltage of a diode during the rise of a 6 kA half sine pulse, compare it to the forward voltage on the trailing edge of the waveform, and calculate the die temperature difference.. A measure of the thermal contact resistance of the composite structure.. The fix brought me into the millivolt range of difference rise to fall, but that low level was not useful in examination of the thermal resistance of the die. In addition, the measurement of voltage across the die required I subtract a measured voltage vs time, as even those taps trapped some flux, they were 100 mils apart. It was a 67 mm diameter diode, and there were 8 cubic inches of copper on either side of the die. In the end, we had to test them at 4.5 kelvin, and determined that the industry standard pressure of 1.5 kpsi was insufficient. 2.5 kpsi was required because the die curled cold, it was brazed to molybdenum.
ps... I've also used this technique for computer controlled ultrasonic welder where I needed to know exactly how much power was being dissipated by the load. The ultrasonic transducer/horn assembly has an unloaded Q of roughly 10,000, so requires extreme control of drive. A simple .1 ohm resistor for current monitoring caused excessive phase shift of the measured voltage, which resulted in an incorrect measure of power delivered vs power reflected. So I used 3 pieces of 300 milliohm resistors in parallel, tightly packed body to body, and ran the v tap wire up the physical center between the 3 cylinders. Worked perfectly.
Certainly.
Hawksford's "mathematically derived and measured distortion" was first of all, derived with an incorrect mathematical model which did not account for the current within the wire, nor the resultant magnetic field within the wire. Had he looked up Terman, published in 1947, he would have realized his error. He did not. A simple inspection of the waveform is all that was needed to realize he missed out on some inductance.
As a result, he miraculously "found" this truly amazing storage mechanism, called it some kind of "loss field" which actually returns energy to the system, and then speculated no end about the wonders of high end audio and the new physics things to be found, pandering to the audience as it were.
Unfortunately, this "loss field" was the internal inductance of a wire. While not very sexy nor worthy of print, it was sitting there in the Terman equation printed in 1947. That'd be, 48 years prior to the essex echo article.
I do not know if Hawksford was even born when Terman published the equation.
As I said, peer review would have saved him professional embarrassment.
Cheers, Jn
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A "scientific" article that cites the audio press as references, this one is worse than the wire articles. The experimental evidence seems to be audiophile listening tests.
So PIM is out? Folks please do yoursevles a favor and start with Gray and Meyer, Sze is good once you understand the basics. There are many more.
Perhaps he did misinterpret his experience as pointed by some,
although i can personnaly give no clue about it..
That said , the thinest technology , the one that get closer to quantic limitations ,
is mosfet on CPUs while he talks of Bjts wich to my knowledge werent as much miniaturized..
Well, I like to see 'explanations' as to what I hear, even exotic ones. It gives me something to think about.
For example, back in 1978, I made a direct listening comparison between two 'op amps'
One was a 5534 IC and the other was a discrete design with jfet inputs and a similar topology to the 5534. Everything was matched to be as close as possible in level, frequency response, and absolute polarity. Both op amps measured distortions was almost unmeasurable, with the best equipment at the time. However these two op amps did have differences that could be predicted by Dr. Hawksford's later 'Fuzzy distortion paper' (By the way, JAES published and therefore peer reviewed)
Still, I could hear the difference between the two. Actually a disappointment, because I had hoped that the 5534 would save me a lot of time and trouble. I mentioned this test to Dr. L, in an LTE dated 1/79 'The Audio Amateur'. What I got back is an ignorance on his part about ultrasonic garbage from phono cartridges (even though I gave Dr. V a copy of my 1978 IEEE paper), and his polite insistence that I do one of his double blind tests, according to his instructions, and report back the difference. Nothing much has changed for the last 33 years!
For example, back in 1978, I made a direct listening comparison between two 'op amps'
One was a 5534 IC and the other was a discrete design with jfet inputs and a similar topology to the 5534. Everything was matched to be as close as possible in level, frequency response, and absolute polarity. Both op amps measured distortions was almost unmeasurable, with the best equipment at the time. However these two op amps did have differences that could be predicted by Dr. Hawksford's later 'Fuzzy distortion paper' (By the way, JAES published and therefore peer reviewed)
Still, I could hear the difference between the two. Actually a disappointment, because I had hoped that the 5534 would save me a lot of time and trouble. I mentioned this test to Dr. L, in an LTE dated 1/79 'The Audio Amateur'. What I got back is an ignorance on his part about ultrasonic garbage from phono cartridges (even though I gave Dr. V a copy of my 1978 IEEE paper), and his polite insistence that I do one of his double blind tests, according to his instructions, and report back the difference. Nothing much has changed for the last 33 years!
Sze?????
Whoa, haven't used him since I had punch-through problems with some diodes. Also had fun with Grove, liked him cause it was a lighter book..
Sze, S.M. Physics of Semiconductor Devices. 1969, John Wiley and Sons.
Library of Congress catalog card number 69-16132.
Man, you goin back a tad...my copy's falling apart..
Cheers, jn
Dr. Hawksford's facility with math far outpaces his mastery of semiconductor physics. Would you propose a whole new model and not cite previous work, I mean there are 50yr. of it? As I said the simple fact that several microamps of DC current in the base with 10^13 carriers per second is always flowing, separating out the behavior of one makes little physical sense.
Fuzzy thinking.
There is an '81 revision, one of our process guys has a guest chapter IIRC.
DF96, if bunch of electrons decide to jump together over the potential barrier that will be audible, like when steam engine releases bunch of water molecules at once. 
Impurities in semiconductors create many different effects one even can imagine, like tunneling, avalanche, parasitic junctions, and so on... I was kidding about single electron charge and steam engine, in my previous message.
I heard a story about how once a lady changed boyfriend that changed properties of production. New boyfriend did not like her old perfume.
Impurities in semiconductors create many different effects one even can imagine, like tunneling, avalanche, parasitic junctions, and so on... I was kidding about single electron charge and steam engine, in my previous message.
I heard a story about how once a lady changed boyfriend that changed properties of production. New boyfriend did not like her old perfume.
You might be surprised what some EE professors don't know about the basics. Antennas confuse some of them, but they are so confused they don't realise they are confused.john curl said:
I once spotted an error in the derivation of antenna noise presented by a prof. I emailed him about, very politely. I got a very terse reply, referring me to the textbook. I checked, and it confirmed my understanding.
Another prof asked me to do some work on a simple computer program he had written, which calculated antenna beam patterns. He was a bit miffed when I found about 6 mistakes in the first week or so, some of which would result in false results. Both of these profs are highly regarded in their own field, lead major research teams, and have a string of peer-reviewed publications. I learnt many years ago that profs are just as fallible as me. These are profs I know and respect.
My guess is that many UK EE students have never heard of internal inductance. That would mean that many of the next generation of EE profs won't have heard of it either. It is more likely that a UK physics student would have heard of it, as they do more EM theory than EEs.
Yes, popcorn noise?Wavebourn said:
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I'm gobsmacked
Dr. Richard Bews, who serves as LFD's managing director, and the well-known audio engineer Dr. Malcolm O. Hawksford, LFD's technical director.
....It was, in fact, from one of the papers Dr. Hawksford delivered to the AES that LFD got its name: Low Fuzzy Distortion.
<punch line>
At the same time, LFD has no particular fear of op-amps, a stereo pair of which is used in the product under review: the Phonostage LE ($1295). According to Richard Bews, the NE5534 op-amp chip that provides voltage gain in the Phonostage LE was chosen specifically for its sound quality
...the LFD Phonostage is indeed as minimalist as they come: 28 resistors, 24 capacitors, 4 regulators, 2 epoxy diodes, 2 op-amp chips, and 1 transformer,
EDIT - Jezz these guys have a $10.000 1.25m interconnect, no shame.
Dr. Richard Bews, who serves as LFD's managing director, and the well-known audio engineer Dr. Malcolm O. Hawksford, LFD's technical director.
....It was, in fact, from one of the papers Dr. Hawksford delivered to the AES that LFD got its name: Low Fuzzy Distortion.
<punch line>
At the same time, LFD has no particular fear of op-amps, a stereo pair of which is used in the product under review: the Phonostage LE ($1295). According to Richard Bews, the NE5534 op-amp chip that provides voltage gain in the Phonostage LE was chosen specifically for its sound quality
...the LFD Phonostage is indeed as minimalist as they come: 28 resistors, 24 capacitors, 4 regulators, 2 epoxy diodes, 2 op-amp chips, and 1 transformer,
EDIT - Jezz these guys have a $10.000 1.25m interconnect, no shame.
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Yes, DF96, I was once a consultant to Dr. R.G. Meyer on PRACTICAL low noise design and topology. Jack Bybee was once a consultant to Richard Feynman on superconductivity. We've 'been around the block.' Sometimes you just have to help these professors, no matter how accomplished they may be. '-)
Well, when it comes to Dr.L and Dr.V. I have read their early work, found errors, that I alerted them to, in 'The Audio Amateur' LTE 3/79. AND personally discussed things with them at AES Conventions (both of them). Did I get a polite reply for my efforts? No. Did they acknowledge my IEEE paper, after I personally gave them a copy? No.
Did I learn anything new from them, or they from me? No.
The last time Dr. L mentioned anything to me in print was in an LTE in 'HFN' in the mid 80's, where he stated that 'while my measurements were correct and my math was OK, that it did not matter, because he and his associates could not separate some of the worst caps (subjectively evaluated earlier by Walt Jung) from the better caps.' What is the point of going forward with this?
Did I learn anything new from them, or they from me? No.
The last time Dr. L mentioned anything to me in print was in an LTE in 'HFN' in the mid 80's, where he stated that 'while my measurements were correct and my math was OK, that it did not matter, because he and his associates could not separate some of the worst caps (subjectively evaluated earlier by Walt Jung) from the better caps.' What is the point of going forward with this?
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