Hi,
Agreed.
In many other areas of electronics it matters (remember, I started professionally in military and industrial control systems), yet as soon as Audio is concerned, according to some, all these differences stop to matter, magically disappear and everything sounds the same...
Ciao T
Agreed.
In many other areas of electronics it matters (remember, I started professionally in military and industrial control systems), yet as soon as Audio is concerned, according to some, all these differences stop to matter, magically disappear and everything sounds the same...
Ciao T
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I am just finishing up my delve into power supply noise and the very basics of how it affects the rest of the circuitry. In order to do that I built a semi-calibrated noise source that would at least be within a db for a run of tests. Then I built many versions of basic power supplies and measured their noise performance. As usual for these kinds of things I do multiple test runs until I have a good handle on what is going on then I do the article runs.
Then I did a few tests on particular circuits and how noise injection affected performance. There was nothing jaw dropping about any of the results. It just demonstrates that if you ignore an issue Murphy will see that it haunts you. Ignorance of the Law (Murphy's) is no excuse.
Next project may be developing a series of actual test waveforms and methods to determine how accurately they get encoded. I have done some basic math models that seem to show the problems. The issue is to make it a physical reality.
I do have the basic idea for a 26 bit A/D 200kHz or so audio converter. I will see if I can shed light rather than heat on where current designs fall short.
As to the -170 ninth, it shows up very clearly on this type of resistor, there is a reasonable explanation why and it is repeatable. The ninth can be greatly increased by some of the design decisions in where these resistors are placed, the circuit topography and even how many are used!
If you want to play let me know and I can send you the parts and a measurement box. The goal of that work was not just to test resistors but to show a simple method for evaluating them. There actually are a few types I did not cover that have use for tweaky audio.
As to V dc/dt, V is the elephant not dc/dt. When a high DC bias is applied to real capacitors (say 100 V) and your signal level is a few mv then -140 dc/dt can be an issue due to the vibration induced dc/dt! (i.e. unwanted signals can be in the -50db range.)
T
I have seen three surface mount thin film resistors that do work well at low power levels. So it would not surprise me if those were the ones you prefer. I will not discuss particular brands as some consider this "Secret" info.
SY,
We agree that voltage coefficient is the one size fits all bucket. Actually with Carbon Composition resistors there is so much going on it is very useful for them.
Note tempco is a guarantee of worst case performance. It is the linearity of that curve in addition to it's slope that matters. If it were just tempco then adding a small varistor in series with critical resistors would provide an improvement. They don't as it is not just tempco that is the issue.
J.C.
The bulk metal resistors do measure very well. It is just that some of the larger Dales offer very similar if not better performance for much less money.
DF
All of my music has discontinuities of infinite duration.
So we have moved down yet another order of magnitude to -170dB. Your last statement implies a lot of experimental data taken on complete amplifier circuits. Bridge measurements of resistors is one thing, THD of an amplifier to -180dB is another. Samuel Groner carefully presents about the limit of what is possible.
When the original AD562 breadboard was built (and I mean breadboard, no simulators at all), Bob Craven's tech made batches of Vishay resistors where you cut links and encapsulated them yourself and in the process expelled the air from the epoxy in a bell jar. He would tediously make 10 or 20 to get 1 good one (checked with a standard cell and a Kelvin Varley divider). I remember sometimes he would over mix the epoxy and it would foam up all over the bell jar.
Scott,
I don't know what you are reading into this. The single resistor produces -170 db in my test set up. That means on it's own it would be -160. If anyone ran an amplifier at full rated power then -148. But in some applications (designs that are in current production) a pair could become -85. Now throw in some real world IM with frequency rolloff and you really could get -65. (Based on real world music waveforms.) Even without Fletcher Munson weighting you get levels that will show up!
ES
Yes they do : Vishay Precision Group - Foil Resistors - Home Page , see under "Why Foil" where they explain that compressive stress on the foil from the subtrate counteracts the positive tempco.
Again this numerology totally escapes me, .05% from just the Vishay resistors how do folks make 10ppm amplifiers at full power? So in some (unknown) applications there is a >60dB degradation in performance, do we just say OK we take your word for it? This stuff needs concise examples for examination by others.
Simple, to make 10 ppm amplifiers you don't use resistors that are among the worst for the task. Then you use circuit topology that minimizes the system's error sensitivity.
We were discussing the worst Vishay metal film resistor results, not the best.
10 PPM is only -100 db. That is also linear frequency weighting. If you model musical energy as having an energy peak around 150 - 300 Hz and rolling off at 3 db per octave and model the ear as having a peak sensitivity around 3,000 Hz of 12 db better than 300 hz then the 100 db can be as little as 74 db s/n weighted on music.
Now look at the distortion at actual operating levels. Many amplifiers have higher distortion due to zero crossing errors. For music enhancement a level 30 db below clipping may be used. Hopefully the distortion doesn't rise by that much because -44 would not sound very good.
No sorry, please post an amplifier schematic that shows .05% distortion from just Vishay bulk film resistors. We have made modular amplifiers with Dale RN55C's that do < 10ppm.
Not a good boy T !
How about this?
…yet, as soon as Audio is concerned, according to some, all these differences are purposely not addressed, magically disappear and everything sounds different…
Yes Scott, exactly.
The Beast* had the virtue to doubt the fallacy and the malpractice found in the circles he was into. This writing of his is an extreme self sarcasm and a splendid way of warning –through entertainment- for the total rubbish that can be served as “spiritual gems” to well intentioned people in the mystic, cryptic, esoteric, hermetic - you name it – circles in the western world.
There is a reason that open scientific methodology, although very slow in it’s outcome was finally adopted over dubious sacred routes, by people who were mystics themselves.
*Certain actions of his and their timing suggest he was not that wacko. May be , no wacko at all.
George
Maybe this helps explain the Bybee, Red Wine, Tartaric Acid, and the Secret of Superconductivity - Technology Review
people understand physics or they don't.
those that can do.
those that can't,
use a code phrase to signify that their limit has been reached,
the code phrase being 'snake oil'.
or the word 'scam', and references to monetary gain.
(except in sy's case, he says something like, 'law of thermodynamics')
the no physics sc/skeptics religion types
aren't able to comprehend this either.
(a religion based on fear)
2,496,059
Attack what attack, people are making new discoveries on superconductivity just a heads up.
You are really saying that those that spout the nonsense understand physics, I say they just ignore it.
no ...
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plasma cam at ucla -
Live view - AXIS 207 Network Camera
http://en.wikipedia.org/wiki/List_of_plasma_(physics)_articles
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John, your efforts are not wasted. There always be some naysayers.
I am sure there are people out there quietly taking notes ...
Best,
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