I was not being technical but I guess that term has a technical use in the industry. I did the experiment years ago (we used a solo violin piece) masked with broadband pink noise. You can go well into the noise and still hear the music.
In this case I simply meant turning up the noise until it was clearly audible (far above listening volume) and not hear anything. I think we were creating a wire junction and amplifiing the potential across it enormously while passing a 19/20k IMD test through it while listening for the lower tones. I was inspired by an article where someone wired an entire 50 pin edge connector in series and did measure IMD (lost the artice but is was in an EE trade journal). I should repeat the test with an ultra low noise preamp, we were limited to 4nV at the time.
Anyone have a point or direction here? It is my opinion that small distortions at moderate signal levels such as 10mV, can be LARGE distortions at 1uV, or where the noise threshold lies and were the virtually subliminal information that separates mid fi from hi end resides to give realism and imaging information. IF there are 'dead zones' or even significant reductions in amplitude compared to ideal, then we have something important.
I like the first part, Simon7k...
But, here we are, obviously you are posting to a DIY forum, not a Phd level reviewed forum. So, the level and scope of the expertise here will be rather wide and varied - in some cases exceeding yours in various points and areas, in others not. I would expect to have to explain and cite/reference various somewhat esoteric things, if only for the benefit of those less learned or expert in a given area than yours, or someone else's. It's not a reasonable expectation that everyone is going to to be up to speed on everything.
Seems like you may have something to add and bring to the table, I know I am interested to see what that may be. Expect skepticism and questions, of course. Not to mention disagreement.
Speaking only for myself, I am slow, somewhat ignorant, and I do need to be spoon fed and have my hand held an awful lot. Ummm, but I seem to be able to change my own diapers, at least for now.
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That was a specific case answer to a poser who had to have the last word, albeit incorrect and off topic. Ask questions, that is fine, point to real references, but don't waste time beating your chest.
On topic
John,
Perhaps a logical approach. Building a preamp starts with a preconception. Analyzing one from the basics would imply starting at the basics.
Wire, connectors, and case have been covered. A bit on capacitors, resistors and switches, moving on to FET's would presume all of the passive considerations have been discussed.
Then there are the issues of user environment. Heat, RF, Vibration, etc.
However unless someone can actually show any evidence other than supposition can micro-diodes go away?
Simon, have you looked through the ENTIRE BLOWTORCH tread, both 1 and 2? Active devices in general and their optimum circuit topology have been extensively discussed. I am not in a position to talk about any esoteric factors that might make a difference, so we are now left with non-linear cap changes in fet gate inputs, and resistor problems.
In the case of the BLOWTORCH, we used a case that was thick enough to stop virtually any normal RFI, and even adjacent transformer radiation, especially at high harmonics. Our environmental temperature is approximately perfect, as we have no turn-on-off changes and no circulating air currents. The unit just gets up to temperature and stays there. Vibration is also at a minimum because of the mass and the plastic feet at the bottom of the unit suspending it from any normal vibration. Certainly many times better than most audio equipment.
Now we come to micro-diodes. Well something makes wire quality, resistor type, etc important. I suspect it is micro-diodes, but I am not in as strong a position to measure them as I would like. If you find anything, Simon, please inform us when you can.
In the case of the BLOWTORCH, we used a case that was thick enough to stop virtually any normal RFI, and even adjacent transformer radiation, especially at high harmonics. Our environmental temperature is approximately perfect, as we have no turn-on-off changes and no circulating air currents. The unit just gets up to temperature and stays there. Vibration is also at a minimum because of the mass and the plastic feet at the bottom of the unit suspending it from any normal vibration. Certainly many times better than most audio equipment.
Now we come to micro-diodes. Well something makes wire quality, resistor type, etc important. I suspect it is micro-diodes, but I am not in as strong a position to measure them as I would like. If you find anything, Simon, please inform us when you can.
Yes I have spent the time reading everything, but a review might turn up things you forgot to mention before as has just happened. You might recall every so often emotions may have clouded the issues at hand. The discussion spent a lot of time on circuitry. As has been mentioned you do not want to give exact details and even with a schematic one would not have all of the data.
Assuming that anyone interested has read the knots, the circular approach allows you to increase the level of detail, build on or reinforce what you think are important issues. I realize you get drop ins who would like you to explain the world while standing on one leg.
The best example of this is that new issues such as FET models have surfaced. (Also I do not remeber that you previously had mentioned plastic feet!)
No argument wire and parts do measure and sound different. As to the causes any one can speculate, that is part of audio lore. I think it is important to identify opinion from speculation or research. Some information is more valuable than others.
Steve Eddy has posted that he has measured micro-diodes, but no more. I have measured to within a few db of the noise floor and can't find any.
But actually the reason for the comments in the last post was my feel that every post should at least contain a bit that is on topic.
Actually, I suspect that Steve Eddy does not believe in the existence of micro-diodes, and I might clarify it with that I NOW think more that micro-gaps that easily get crossed over at higher voltages or currents are sometimes in the way, so to speak, of easy access and perhaps might create a change in the resistivity at some very low level. This is a hard to reach area in measurement.
I never claimed that I'd measured micro-diodes.
That was John who made that claim.
And no one else has found them either, even when measuring better than 20dB below where John was capable of measuring.
se
Copper oxide rectification is the proposed mechanism I assume. One problem is that it was known in the industry that copper from Chile made the best rectifiers so the mechanism is not perfectly understood. I have some old Weston AC meters that use them. The best question is how do you get a potential across two strands. I guess a good test would be to take a mutli-strand wire and grab half of the strands from either end forcing all the current to get from one side to the other. I never saw anything.
Something else to worry about http://home.earthlink.net/~lenyr/photocell.htm
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I believe John is inferring that the microdiodes exist within the wire strands themselves, not a strand-to-strand thing.
As far as I'm aware, you don't get a diode if you go from copper, to copper oxide, to copper. You have to go copper, to copper oxide, to something other than copper. I believe lead was commonly used for that in copper oxide rectifiers.
se
... which is no problem to measure nowadays.
To me, the microdiode theory is a rubbish, marketing rubbish.
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