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Re: Accuracy is not "minutia".

Hi CJ

Well, the discussion was of power cords and an assertion that they could develop a meaningful “difference” from one end to another.
The point was, unlike loudspeakers which ALL suffer from measurable dynamic compression due to conductor heating, that an AC power cord wouldn’t even be warm in “hifi” unless it were faulty.
Yet, people “hear” differences in power cords while they are essentially unaware of a significant real issue in the speakers they listen too. The difference is speaker companies do not “sell” off of that issue.

All loudspeaker drivers large or small have a “rated power”, that level is set by the thermal capacity of the Voice coil. That capacity is set by its surface area and maximum permissible temperature.
“Modern” loudspeaker Voice coils are wound with wire having insulation which withstands high temperatures and many used ccaw (copper clad aluminum wire) as well.
The increased thermal capacity is primarily “how” today’s speaker handle so much more power than those of the 70’s where T max was more like 125C.
At the same time as the “modern” glues allow such a high temp, that also produces far more dynamic variation. For example, did you know that if you measure a speaker at increasing levels, that starting at about 1/8 or 1/10 rated power, the response starts to change and in some High power drivers, an increase in input power results in NO increase in output SPL.

In the originating post, it was asserted that the tuning rod caused a phase shift and there was a concern that this would alter the charging of capacitors (wrong, the caps are driven by a rectifier if the input voltage doesn’t change, neither does cap charging).
While the rod might cause a change in phase if “open circuit”, it is not possible IF the cord were connected to a supply and load as the impedances are so much lower.
Of course, had they measured the cord as intended, the rod would have been “invisible” to the measuring instrument.

Fwiw, a common mode choke (your ferrite clamped around a cord) is an effective way to de-couple hf common mode noise (like the cord picking up a radio signal).
In the old days (the 70’s when I worked at a TV store) TV’s had these as the first thing past the AC connector inside the chassis.

Best,

Tom

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