Measuring 1nV riding on 10mV means CMRR is an issue. Perhaps you don't understand what CMRR is? It is not just a spec for an instrument; it is a figure of merit for the whole apparatus.simon7000 said:
The four parameters won't vary that much across the audio spectrum.Speedskater said:
The OCOS cable seems to use a conductive dielectric. It greatly increases G so it swamps C so at audio frequencies the characteristic impedance is given by sqrt{R/G}. For typical short audio cables the same effect can be realised by adding a shunt resistor at either end of the cable, but that would not impress the gullible.
Wide conductors, closely spaced - a bit like a giant stripline. This greatly increases C.RNMarsh said:
Apparently MKSA doesnt exist in some parts of the world..
Coax, strip line, paralleled twisted pair as in cat5e. Mainly just techniques to
Control the spread of magnetic field.
The constraint is LC=1034 times EDC. EDC can never go below 1, twisted pair is about 4. L in nh/ft, C pf/ft.
For coax and strip line, EDC is the pemittivity of the dielectric. Range of about 1.05 for foam to 3 for common plastics.
Nordstrom goes for lowest capacitance and reduces inductance by increasing the reluctance path around the conductors. As I recall, they run 90 nH per foot, and EDC of about 1.1.
To get to 8 ohms, Ls has to be roughly 10 nH/ft, C around 300 pf/ft. Which makes the zobel important.
There are diminishing returns in going so low in Z, once you get to the 20's, the load impedance settling variance goes below any audibility threshold.
For thousand foot runs ala Ed, load spread vs frequency may be a more significant factor. That is why I wanted him to run settling time tests for the long run and load resistors ranging fro 4 to about 200.
John
There s some bad habits that are surviving, certainly that for enginering related discussions it s better to get rid of antiquated and non mutualy related "metrics".
I just noticed that the metric system is not legal in the US, so people from there have an excuse but i imagine the difficulty when converting surfaces expressed in squared inches to squared feets and so on.
Are wave lengths also expressed in feets or miles..?..
Other than this JNeutron is providing some good clues about those forever discussed wires..
How much cubic feets is a cubic inche..?.
That s a very bad exemple where you have the things backward, Miles/Gallon
amount to km/litre....
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If that's true, I am committing crimes every few minutes. I suspect that's not true.
Actualy i also thought that they were both used in the US but apparently only the UK and Canada have both systems being of legal use, in the US the metric system is just used to reference the imperial measures and for scientific matters..
https://en.wikipedia.org/wiki/File:SI-metrication-world.png
IIRC a 300m$ space probed was crushed because of US enginers using imperial lengthes in an internationaly devellopped project..
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