An argument for fuses and maybe power cables in power amplifier

     Back in March 2022: a thread about power cords and break/burn-in was started.

     I hate to type, so: I'm going to copy/paste some of my speculations.

     That a highly complex musical signal, MIGHT affect Poynting vectors and signal speeds*, in interconnects, in a much more profound manner than a simple AC (ie: a fixed 60/50 Hz) signal, in a PC, seems likely (at least) to me, as; in EVERY formula regarding *those two, a signal's frequency (frequencies) always factors in greatly.

     Further: the above and what I'll c/p (seems to me) lends credence to how the application of a stronger, DC voltage/field, outside a dielectric (ala Synergistic MPC and Audioquest DBS systems), might stabilize those vectors and signal speeds, PERHAPS eliminating some time smear and, "burn-in". 

rodman99999 5,456 posts 03-31-2022 at 12:13am    @holmz-       Bear with me a minute, in my folly, far as a possibility on why a power cord might make a difference.       Based on some of the theories on how electricity works, simplified:       The conductor acts as a waveguide for the signal/voltage.       Within the conductor: when excited by an AC current, electrons oscillate, generating photons/electromagnetic waves that travel, always from the source, to the load.        Keep in mind: all signals (ie: music, AC) are sinusoidal  waves        Those photons/electromagnetic waves travel through and outside the dielectric, which (according to it's permittivity/Poynting vectors) will have various effects on those waves.    One of the most obvious is the dielectric's effect on the speed of the signal.       The better designers of printed circuit boards, even take the above into account, when choosing materials for their products.        I posted a link on the first page that included data on the manufacture of semiconductor chips and what was observed when materials were cryo'd, during the process.     Short version: better contact/lowered resistance between layers.           Under the scanning microscope: much smoother surfaces observed.        I would hope, by now, it's a given that various cable constructions, twists, braids, etc, can make for a cleaner transmission of signals (ie: Litz, etc).                     Just seems to me (a hypothesis): given the above (some theories and some things established/measured/proven), it's not a big stretch to believe a power cord, built of the best conductor (ie: Ohno CC silver*), wrapped in a very low dielectric coefficient dielectric (ie: Teflon), cryo'd for the smoothest transfer of those photons/magnetic waves and twisted in some crazy way, might not smooth out some of perturbations/noise, from the crap an AC waveform had to go through, back to it's generator.  (run-on, much?)          *Many mention NOT noticing an improvement with upgraded PCs, when owning Pass Labs gear (KUDOS to Nelson).   Of MUCH interest is the fact that Frank Dickens, the owner of Silent Source cables is basically on staff with Pass and: they voice their equipment with his cables and power cords, made largely with Ohno CC metals.        I haven't tested this, actually comparing two circuits, but: it wouldn't surprise me, if a power supply that used a choke, would be less affected by a better power cord, as the former can eliminate a lot of the high freq garbage, etc, that's either created by, or makes it through all the big converting/filtering stuff, in the power supply, before.        Never thought about PCs before the good stuff hit the market, but: the Physics/QED made sense.             I tried 'em, I like 'em and the science makes my head feel better.                               Don't care WHAT it does to anyone else's!

rodman99999 5,456 posts 03-31-2022 at 12:27am         OH, and: it takes some time for the dielectric to form, take a charge, polarize, or however one chooses to define the process, when a dielectric is subjected to electromagnetic waves, which affects the Poynting vectors, measurably/predictably.                                             The lower the material’s dielectric constant: the longer that takes.                                                               PC (interconnect/etc)  burn-in?    Maybe?

                                                                                         Happy listening! 

                                                   btw:

             I'm not disagreeing with any postings, prior to mine, in this thread.

             ie: everything in the power supply/AC source is in the signal path*.

       *In every gain stage: DC power supply voltage is modulated/magnified, as directed by the musical signal, via the circuit designer's gain device(s), be they SS or valve.

                 A cleaner/more pure DC voltage = more faithful musical output.

I can remember reading an audio equipment circuit designer saying a power cord is not an extension of the branch circuit wiring in the wall but rather an extension of the primary winding leads of the power transformer.

Fuse. The purpose is to provide short circuit/overload protection.

A good fuse clip will provide good surface area and good fuse clip to fuse contact pressure. Poor contact pressure can cause series micro arcing creating ac RFI noise into the primary winding of the transformer. My understanding the frequency of the series arcing will pass onto the secondary winding(s) of the transformer. Using the simple drawing supplied by the OP you will notice the center tap of the secondary winding is the B- of the power supply, signal ground, and in some fashion connected to the chassis of the equipment. (Note: I am not an EE or audio equipment designer.)

After market fuse. No opinion one way or the other. Never tried them. A lot of audiophiles who have and use them, swear by them. Their listening experiences works for me. ( I just got this thing about is the fuse tested and Listed by UL or some other NRLT recognized third party testing laboratory?)

After market power cords: The majority of actual listening tests I’ve done has been connected to digital equipment. Tried some that degraded the sound and others that improved the sound. Some noticeably improved the sound, at least to my ears... And that’s all that really matters to me.

The why after market power cords make a difference? Lots of theory... Actual testing using testing equipment? Just my ears. I don’t watch oscilloscope screens or listen to test tones. Just music using my ears. YMMV

.

The why after market power cords make a difference?  Lots of theory... Actual testing using testing equipment? Just my ears. I don’t watch oscilloscope screens or listen to test tones.  Just music, using my ears. 

                                       And: that's ALL that matters!

                                                     YMMV

                                                           +1

      Some people just don't seem to understand; there are a plethora of variables.

                                                  Happy listening!

Linear power supply is really a primitive switcher operating at 120Hz.  Current is drawn from the mains in narrow spikes of high amplitude, that become wider when load increases.  In addition rectifiers become reverse polarized at the peak of the voltage conducting for a moment in the opposite direction creating narrow spike that couples to any, even smallest inductance in the circuit.  

The fact that current is drawn in narrow spikes has serious consequences.  Transformer has to be larger than one with resistive load, because higher rms to average current ratio is causing bigger losses in windings, while high frequency content increases core losses (eddy currents, hysteresis).  These narrow current spikes of high amplitude travel thru fuse and power cable making things very complex.  

As for the power delivery, it should be obvious from the definition of electric current (flow of electric charge), that the exactly same amount of electric charge leaving one leg of power supply comes back in another.  Power has to be delivered different way.  Current in the wire creates magnetic field around conductor while presence of load makes voltage drop - an electric filed.  These fields cross each other like X-Y axis while Z axis perpendicular to them shows direction of the power delivery (Poynting vector).  Power is absorbed by the load from electromagnetic wave.

To improve linear power supply circuit I would look for “soft” rectifier (like Hexfred) , that, after conducting for a moment reverse polarized, don’t snap back too fast (wider spikes are better).  I would also look for low inductance electrolytic capacitors, like “slit foil” type.  0.1uF capacitor in parallel helps, but with large inductance of main capacitors can create parallel resonance circuit and possible ringing.