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What causes resistor distortion?
What causes resistor distortion?
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Old 21st January 2020, 04:08 PM   #181
N101N is offline N101N
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Battery + supercap + ice cold mineral oil over the circuit board..
"Dogs bark at what they do not know." - Heraclitus
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Old 23rd January 2020, 03:43 PM   #182
N101N is offline N101N
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NickKUK,
you may have disregarded a relevant snake oil aspect.

The ratio of magnetic energy and thermal energy is a rough thermodynamic measure of efficiency. Another measure of efficiency is the magnitude of excitation energy. A higher efficiency impairs the paramagnetic property which decisively determines signal transfer quality. Who does not like high efficiency and low distortion? Sadly, they cannot coexist in the same physical system.
Again, distortion is much more than just thermal noise.
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Old 24th January 2020, 10:16 AM   #183
jfetter is offline jfetter  Costa Rica
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What causes resistor distortion?
If this thesis is fact, then we may never get lower distortion than metal film.
The foil resistors introducing a casimir effect.

Electronic zero-point fluctuation forces inside circuit components
https://arxiv.org/pdf/1612.03250.pdf
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Old 24th January 2020, 02:52 PM   #184
NickKUK is offline NickKUK
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Originally Posted by N101N View Post
NickKUK,
you may have disregarded a relevant snake oil aspect.

The ratio of magnetic energy and thermal energy is a rough thermodynamic measure of efficiency. Another measure of efficiency is the magnitude of excitation energy. A higher efficiency impairs the paramagnetic property which decisively determines signal transfer quality. Who does not like high efficiency and low distortion? Sadly, they cannot coexist in the same physical system.
Again, distortion is much more than just thermal noise.
My point was scientific method. Measure, theorise, model and test
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Old 24th January 2020, 09:53 PM   #185
DualTriode is offline DualTriode  United States
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Hello All,

I am away from my tools for a few days at the beach.

Sitting here looking out the window, at past data and Bruce Hofer’s Audio Xpress article.

Bruce gave the impression that there was some lumping or local peaking at 5 to 200Hz, “Problems occur in a middle zone of approximately 5 to 200 Hz”. The sliding FFT data for the Vishay PTF65 resistor did not show any localized distortion for the PTF65 1000Ohm resistors in that 5 to 200Hz range. The data did show gradually, smoothly increasing distortion with decreasing frequency. The increasing distortion looked like the graph in Bob Cordell figure near page 370 in his new Power Amplifier book 2nd edition hardback.


Looking at the Vishay sliding FFT data for the Vishay Bulk Foil S102 1K Ohm resistor,
This resistor smoothly increased distortion with decreasing frequency. The slope of the increasing resistance with decreasing frequency was much steeper. The measured distortion was much higher for the Bulk Foil resistor compared to the thin film NiCrome metal film resistor.


The Bulk Foil resistor has a much lower Thermal Coefficient of Resistance than the thin film NiChrome resistor, yet it increases distortion much faster and higher with decreasing frequency.


I also tested some Vishay RN65 milspec metal film resistors. Lower TCR RN65’s had lower distortion than higher TCR RN65 resistors. Smaller size (smaller thermal mass) RN55 milspec metal film resistors had higher distortion than the RN65.


What is the mechanism of injury? What causes resistor distortion? Don’t know! The cause of distortion seems to be similar but different for NiChrome metal film and Bulk Foil.

Increasing TCR increases distortion, I am thinking the assumption that the mechanisms are different but both mechanisms are functions of heat and frequency.


Thanks DT

Last edited by DualTriode; 24th January 2020 at 09:58 PM.
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Old 24th January 2020, 10:35 PM   #186
jan.didden is offline jan.didden  Europe
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DT, is this data you measured? Is that available somewhere in graphical form?

If distortion rises with decreasing frequency, higher TC and smaller size, that would indicate thermal modulation, i.e. the resistance varies due to cyclic heating and cooling.

Jan
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Old Yesterday, 12:19 AM   #187
DualTriode is offline DualTriode  United States
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Originally Posted by jan.didden View Post
DT, is this data you measured? Is that available somewhere in graphical form?

If distortion rises with decreasing frequency, higher TC and smaller size, that would indicate thermal modulation, i.e. the resistance varies due to cyclic heating and cooling.

Jan
Hello Jan, Yes measured by me. Some of the plots are posted in this thread. Some data was less formal, as in after the test/plot I wrote a note in my lab book.

Yes I believe that the distortion is all about heat input (watts) plus cyclic heating and cooling.

I will retest a few resistors and post some test plots here after the weekend if you would like.

Thanks DT
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