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In Reply to: RE: optimal power cord length? posted by rick_m on February 22, 2012 at 08:28:56
Rick by Testing.
First the amplifier using different lengths
Then the CD player which power source is
lower level voltages. Noise is more prevelant
at lower power levels.
Complete testing can be found at
FREE 226 pages of research.
Wow! Was that a labor of love?
It's kinda down my alley as I hail from the world of Smith charts, scattering parameters and VSWR. And measuring tiny phase shifts as a Fn of skin depth and other factors in the audio region for that matter so hopefully much of it will make sense.
However I can already feel some questions arising but they may be resolved once I read enough to get more of the gestalt of it. Are you be amenable to discussion?
Where do we start?
It will be nice to talk to a fellow RF-GUY.
The notion that RF rules do not apply
is what lead us down this road.
I found all your work interesting BUT, the bit that surprised me the most was your recommendation against the use of hard plastics like Teflon.
I agree with you as I prefer the sound of silk insulation best, however, I find it hard to reconcile that the whole audio industry idolizes Teflon when there is bodies of research like yours that point to the other direction.
What am I missing here?
The tradition is to ignore the static-fields
of a signal. Static and magnetic fields are
inter-dependent in signals and this inter-dependence
is especially significant in a audio signal.
Static fields are not 'supported' in a
LOW numbered-dielectric constant like:
DK of: 2.4 to 2.7 - as in TEFLON.
Permittivity in TEFLON is low, that is the insulation
will not allow static fields to penetrate into the
insulator. The static fields are then forced to
stay close to the surface of the conductor.
The 'distorted' fields interfere with the magnetic-electron
portion of the audio signal.
Fidelity of the signal is distorted - damaged.
Sibilance information is lowered - sound stage is
collapsed and leads to smearing.
Coax cables make poor inter-connects as compared to
wires with softer insulations or a higher DK number.
You can test this out for yourself - use coax compared to
a simple cheap soft insulated ZIP-cords
(white to clear - insulation.)
"The notion that RF rules do not apply
is what lead us down this road."
Well, physics (nature) IS largely indifferent to our intentions...
I've finished reading your materials and the part I liked the best was the correlation of our ability to hear mid-range phase shifts with our speech recognition capability. That makes a lot of sense now that it's been pointed out to me!
As far as the RF performance of cables, it depends... I see it as a secondary effect that only affects AF if it causes intermod at either end. Whether it's due to signal pick-up or reflections, the root cause of audible problems is always a design flaw in the active I/O stages that allows energy to enter that they don't have the GBW to handle. As all those loop-d-loops on your Smith Chart show the real world is ugly if you don't have a conjugate match at the load and if there is anything certain in home audio it's that you won't, not even in-band!
I use magnet wire, open-line interconnects (~300ohms) between most of my gear (cheap way to get low dielectric absorption) and normally they sound best with a resistive termination at the load and a build-out at the source. At the power-amp/speaker end of things I've found that frequently hanging a real resistor at the speaker terminals smooths out the highs. I think many speakers largely unload after the tweeters go inductive and there's nothing like a little real loss to calm down a system...
The watery filters in the back are very odd indeed. Do you have any measurements of their impedance vs F over a few configurations?
Thanks for the interesting read...
"Where do we start?"
Well, for me that's easy, I'm a readin' your tome!
Interesting so far, good plot line, decent character development, can't wait to see how it ends...
Audio systems are more whodunits than they are communication systems at this point in time so they have the allure of a good mystery, the emotional involvement of an engaging romance and the intellectual fascination of a challenging engineering problem.
And with the author willing to explain just how the upstairs closet became the focus of the investigation if necessary, it doesn't get better than this! Even if it IS forcing me to learn more about speakers and crossovers, areas that I've studiously avoided for decades, I'm having fun.
Thanks for making this available and I'll be in touch once I learn enough to be dangerous.
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