Home Propeller Head Plaza

Technical and scientific discussion of amps, cables and other topics.

[ Follow Ups ] Thread: [ Display  All  Email ] [ Propeller Head Plaza ]
[ Alert Moderator ]

Re: Shielding is capacitive, not "inductive",

Hi

Many of the arguments for “why” exotic cordage might help sound plausible and are based on real things.

On the other hand, it is the magnitude of problems that govern “if” they matter or not in the big picture.
For example, the reference to heat and wire.
In loudspeakers, heating is a real and not often measured or acknowledged problem.
The fact is that at about 230 degrees C, the resistance of copper wire has doubled.
In “modern” loudspeakers, it is very common to have Voice coil wire with a failure of over 350 degrees C.

Here, the amplifier load IS the driver Rdc plus the electromechanically reactive components so one has a very marked change in driver performance as the coil heats and parameters change as a result. This heating produces a very pronounced departure from a linear relation ship between input and output level.
ALL electromagnetic speakers become dynamically nonlinear above about 1/10 to 1/8 the drivers rated power.

On the other other hand, lets take a cord for a 100W amplifier. It is at least 16 Ga wire which has a TINY Voltage drop at full current draw and so even “IF” the cord was at 230 degrees C (producing stinky smoke too) its Voltage drop is still insignificant.
ANY cord, not just DIY, IS DANGEROUS if it is this hot as most insulation is not designed for high temps (125 - 150C is more normal). Normally, if a power cord feels warm at all, it is going bad unless the cat was just lying on it.

Power supply design and shielding can be frustrating but is no mystery either, this is how one can build a mic pre-amp inside a transmitter or in my case, build a high voltage mic pre-amp next to a 300W power amplifier and 100Amp pulse width furnace controller (flown on STS-7 and STS-51a).
Even the 100A modulator passed the conducted and radiated emi specs.

Yes, you can miss something by measuring, there are no magic arrows that appear on the display that say “look, here it is”, that diagnosis is the job of the measurer as well as deciding what to measure.
AS it is with test equipment, if an exotic cord makes any difference, the power supply design is suspect.

The problem for tweekers (I see) is they are depending too much on “lore” spread by those who sell exotica and there impressions of “what it seems like” only rather than “what is”, observed by proper measurements or (sigh) unsighted verification of impressions.
Best,

Tom Danley


This post is made possible by the generous support of people like you and our sponsors:
  Schiit Audio  

Follow Ups Full Thread
Follow Ups
You can not post to an archived thread.

[ Top Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2025, Audio Asylum, all rights reserved ]
[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]