Pretty easy - bit of corrosion forms inbetween, say some sulphides, and metal to metal sulphides contact has been around for yonks as a current rectifying mechanism ...
The "story" even has its own thread here ... http://www.diyaudio.com/forums/cons...esigning-ultra-low-thd-n-analog-circuits.html
Oh, so measurements made using something more than a multimeter or an analog 'scope are "exotic"?
BWAAAHAHAHAHAHA!
se
Oh. So "exotic" is really just code for "my dick's bigger than yours." Got it.
Well let's see what you can do with your new tool, John. God knows we weren't terribly impressed with those "micro diodes" you claimed to have "measured" with your old ST/HP setup. Will be interesting to see what you "measure" with this one.
se
An ‘exotic’ difference is a difference dressed in Hawaiian clothes, dancing hula hoop.
Most probably, JC is speaking about ‘extra terrestrial’ differences.
Although 1% and smaller entities can be seen using multimeters and analog scopes, reliable detection of ‘extra terrestrial’ entities requires the investigator to adopt a different mind set and posses instruments unseen by most on planet earth
George
What about PCB traces, they carry low level signals, especially in feedback loops, and with the penchant for through hole components, traces can be quite long, then we have the leads of the various devices, are all these directional, and on a PCB how do you determine the correct direction?
That's because that wasn't that I said, Ed. Your article is fine; I wish you'd do more like that.
I wasn't even addressing a specific article or person. I was making a general remark that hi-end progresses by basic engineering by those that are often sneered at .
Jan
This tiny exchange happened because of a comment by Kindhornman, here, http://www.diyaudio.com/forums/loun...ch-preamplifier-part-ii-5048.html#post3890205. I'm not particularly interested in such matters, there are much bigger fish to fry, so to speak - but it can be of value in considering a possible reason for an artifact occurring ...
A different distortion test. Could this work ?
It was either a new thread or post the idea here 😉
Now I had a real crazy idea... and it goes something this...
A normal distortion test uses a continuous sine wave as a signal source but we all know that music is asymmetric. Does the distortion profile of an amp "change" when handing asymmetric signals as opposed to steady state sinewave ?
Now for the crazy bit, and I really don't know if this could be made workable or not, and also would this be applicable to simulation as well as "real" amplifiers.
So the method. You have two test signals, one consisting of only positive going halves of the sine and one of the negative going section. The zero crossing point would have to be exact. Is that do-able in itself ? (I'm guessing you would need something better than Audacity and a laptop for that and have samples exactly aligned).
You apply just the positive test signal to the amp under test and record its output on a PC or whatever. You then do the same for the negative test tone and then carefully align the two files. Ideally you should now have a perfect sine wave that could be subject to distortion and FFT analysis. In an ideal world it should be the same as if the amp had been tested with a continuous tone. I'm sure in practice you could never come close to getting perfect files and alignment but I wonder if it could show "trends" in certain amplifiers and explain why we prefer some over others.
And for simulation you could have two identical "circuits" running and sum the pos and neg halves from each amplifier output in a mixer and look at the residual there.
Impractical, impossible 😀 or just plain mad 🙄
It was either a new thread or post the idea here 😉
Now I had a real crazy idea... and it goes something this...
A normal distortion test uses a continuous sine wave as a signal source but we all know that music is asymmetric. Does the distortion profile of an amp "change" when handing asymmetric signals as opposed to steady state sinewave ?
Now for the crazy bit, and I really don't know if this could be made workable or not, and also would this be applicable to simulation as well as "real" amplifiers.
So the method. You have two test signals, one consisting of only positive going halves of the sine and one of the negative going section. The zero crossing point would have to be exact. Is that do-able in itself ? (I'm guessing you would need something better than Audacity and a laptop for that and have samples exactly aligned).
You apply just the positive test signal to the amp under test and record its output on a PC or whatever. You then do the same for the negative test tone and then carefully align the two files. Ideally you should now have a perfect sine wave that could be subject to distortion and FFT analysis. In an ideal world it should be the same as if the amp had been tested with a continuous tone. I'm sure in practice you could never come close to getting perfect files and alignment but I wonder if it could show "trends" in certain amplifiers and explain why we prefer some over others.
And for simulation you could have two identical "circuits" running and sum the pos and neg halves from each amplifier output in a mixer and look at the residual there.
Impractical, impossible 😀 or just plain mad 🙄
The problem there will be the bandwidth limiting. Think of what the spectrum of that half-sine looks like. There's much easier ways of getting an asymmetric test signal.
Frank I tried to drop the subject because your example was so full of holes. You bring up such incredible examples sometimes it does make me want to add you to my ignore list at time. You just grasp at the absurd at times. Not going to get into all the questionable details that would make you have to think this through. I am not saying there are no things going on at a micro scale but not enough to get the results you always bring up. Keep tweaking, perhaps sometimes you will think about how some things actually happen instead of assigning exotic problems to simple solutions.
Is that a revelation that a ceramic cap can cause some forms of distortion, I thought it was well known not to use certain ceramic caps in audio circuits?
Is that a revelation that a ceramic cap can cause some forms of distortion, I thought it was well known not to use certain ceramic caps in audio circuits?
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